Wordless Weekends

Wordless Weekends

Building Bridges Again

The physics class is starting our second bridge project today. The bridge requirements are as follows:

• Minimum dimensions: 3 cm tall, 5 cm wide, 25 cm long
• Maximum weight (including all toothpicks and dry glue): 20 grams
• Height must be measured above the table level
• Weight must be able to rest on top of bridge

The students did some measuring and found the following information:

• Mass of 1 toothpick: 0.12 grams
• Length of 1 toothpick (point to point): 6.5 cm
• Avg. percent of weight from glue in 1st bridges: approx. 25%

They had to draw plans and make calculations showing how they would build the bridge within the parameters. Later today they will start the first phase of building.

Dreams of graduation

My director came to me today to see if I could help a senior get the 1.5 credits (a year and a half) of science that she needs to graduate. She was in a science class but it was too hard, she wasn't going to pass. So that would be dropped from her schedule.

So that means less than 3 quarters of the year to make up a year and a half of credit. When the 11th grade science class she was already in was too hard.

And all because her parents don't think she should be punished for the bad choices she made in the past by not being allowed to walk with her friends at graduation.

Flying

I'm tired of hearing about the "violations of privacy" issues with the new body scanner/pat down security procedures. Either we can have privacy or security, or some of each. But we can't have 100% privacy and 100% security.

Are we really Ok saying that only people who look "suspicious" should be checked? Who do we trust to decide who is "suspicious"? We have seen in drug trafficking that innocent and innocent-looking people have been used by the smugglers for years. Why wouldn't the same become true with terrorism?

Every year we see more "home grown" terrorists. What happens when they start to look like your next door neighbor or your brother? Who do we deem clever and observant enough to know which person should have the privacy violated and who shouldn't have to put up with it?

I know there are dozens or hundreds of other arguments on either side, including whether anyone has the "right" to fly in the first place. But I am just tired of the constant whining and bickering.

Performance Pay

I am deep in the midst of implementing a teacher performance pay project. And at the moment, it seems to be making me a worse teacher instead of better. I am spending so much time in meetings and dealing with paperwork that I don't have time to be prepared for class.

Breaking Bridges

Today we testing the Physic's students toothpick bridges. They had 30 toothpicks and had to span a 15 cm distance. We don't have a real set of weights, so we had to improvise. We started with a plastic container with salt, adding 100 grams additional salt each round.

When that container was full we took a plastic beaker and started adding D batteries, each has a mass of about 140 g. We go to 1,200 grams with 2 surviving bridges by the end of class. As a class we agreed that one had a better design and should be the winner.

Wordless Weekends

Power's Out!

It was going to be Wordless Weekend. But the power is out and I'm not terribly good at blogging from my iPhone. If the power (and Internet) return I will replace this with something better.

Cats-Masters of Fluid Dynamics

Apparently the way that cats drink water is actually pretty amazing. In fact the cat "balances the forces of gravity against the forces of inertia" and takes advantage of fluid dynamics with amazing efficiency. Even the big cats like lions and ocelots use this same mechanism.

There may be future uses of this knowledge in the field of "soft robots" with nonmetallic parts.

Read all about it:
http://www.washingtonpost.com/wp-dyn/content/article/2010/11/11/AR2010111107897.html

But this isn't English class!

I'm giving tests today in both Chemistry and Physics. And both tests will include a short answer question that will require an answer in complete sentences. In physics they have to write an actual paragraph.

This should not be news or a big deal, but it will be. Students will argue with me about their answers. They will tell me that they just forgot that a sentence starts with a capital letter and ends with a period (or other punctuation). They will tell me that the obviously lowercase letter is just how they write capital letters. They will defend their paragraph-length run on sentence as grammatically acceptable.

And they will tell me "This isn't English class!"

Because apparently the only place in the world that writing should happen is inside the English classroom...

Standardized testing

Standardized testing is one of my least favorite things. It measures only a tiny amount of what we really want students to know and be able to do. And very often they don't test that very well either.

We are giving the PLAN and EXPLORE tests from ACT today and the students really don't take it seriously. They go through each section as quickly as possible and don't take the time to really try their best. Which means that the results will not actually reflect the ability of these students.

So how do we get the students to really try their best? It really does take effort and energy to take a challenging test and really push yourself to the limit of your knowledge.

Or, how do we get the test results to have less weight in the discussion about schools when we know that they aren't really representative anyways.

Physics Phun

So I thought I would write about some of the other activities we have done for Phantastic Physics Phriday.

One of our first challenges was to move a playing card the farthest distance without direct contact.

The rules were as follows:

• You can not touch or blow on the card
• You can not change the card itself other than to add things to it (no cutting, tearing, bending, etc.)
• You can build a device to move the card, but it can not be in constant contact with both you and the card (you can't just push it along the floor with a stick)
• You can not simply drop the card from a high location and count the fall as your movement.
• You can launch your card with some device and count its trajectory as movement.
• If you aren't sure if something is allowed, ask your teacher

The students worked in teams of 2 and were given about 25 minutes and access to materials such as balloons, straws, tape, string, rulers, bouncy balls, marbles, scissors, and other things that they asked for.

Students came up with a huge number of possibilities.

One team made a simple catapult but they were disqualified when their playing card (attached to a marble to add weight) ended up on the roof of the school.

Another team ran a length of string from one corner of the room to the other and attached a balloon to the playing card and a piece of straw to the other side of the balloon. They ran the string through the straw then blew up the balloon and let go, using the balloon to propel the contraption along the string.

A third team used a similar idea, attaching the card and some wings to a balloon before blowing it up and letting it go.

The winning team moved their card all the way down the hallway, about 5 or 6 times farther than any other team. They took 4 balloons (one for each hand of each partner) and taped a section of straw into the mouth of each one. Then they blew up all four balloons and held them closed. They put the card on the floor and used one balloon at a time to blow the card down the hallway. They aimed the mouth of the straws underneath the edge of the card so that it glided like a hover-craft.

It's pretty exciting what students can come up with when given a challenge and freedom to explore their own ideas.

Monday, Monday...

It is Monday of what promises to be a crazy week. This morning before school I had an almost hour long meeting. Two days this week we have conferences after school. And the other two days we have some kind of shortened schedule.

Add that to having a mixed single/block, every-day/every-other-day schedule already and it adds up to a very exhausting week.

Also, my clock didn't get changed in my classroom for Daylight Savings. It doesn't bother me because honestly if I'm looking at that clock I'm really just checking the minutes not the hour. I know the hour because I know what class period we are in. But all day long kids kept commenting and complaining about it.

Maybe I will take a nap when I get home...

Wordless Weekends

Wordless Weekends

Phantastic Physics Phriday

Every Friday in Physics we take part of class to do something different. Something that isn't notes, worksheets or labs that require lab reports. Sometimes we watch a video sometimes we have a building/creating/problem solving challenge.

For the problem solving challenge today the instructions were given one at a time instead of all at the beginning. The students didn't know what the final challenge would be until the end. They had to complete each step and then wait for further instructions. This helps balance out the students who work very fast and very slow.

Today's Phantastic Physics Phriday Challenge Activity:

1. Students were given a piece of cardstock, a pushpin and a pre-cut piece of string. They were told to tie the string to the pushpin.
2. Then they were told that they had to use the string/pushpin and a writing utensil to draw a perfect (or as close as they could get) circle on their cardstock. No further instructions about how to do that were given. Students could ask for additional materials if they wanted.
3. The students had to cut out their circle, keeping it as close to a circle as possible.
4. The students were told that they would be using their cardstock circle as a measuring device and that they needed to calculate its circumference.
5. They were told that they would be using their circle to measure a distance on a flat surface. They could add any additional marks or measurements to their circle to make it into a measuring device. They were reminded that having more graduations on a measuring tool makes it more precise, but only if the placement of the markings was accurate to begin with.
6. Seven markings were placed on the table and labeled A through G. Each student was given a distance to measure, A-C or B-F, etc. Each student had a different distance so that there would be less comparing of answers.
7. Students were allowed to measure their distance multiple times and add markings to their circle. They were not allowed to make any marks on the table or use any additional materials, to increase friction and get the circle to roll better for example.
8. The students submitted their measurements on a piece of paper as a competition to see who got closest to the actual distance.

Overall this went really well today. We actually had 5 students get with in 0.3 cm of the actual measurement and the distances were all between 20-60 cm. It was fun to see the different strategies employed by various students.

Definitely a successful adventure.

It's not a real force!

Today we are learning about circular motion along with centripetal (real) and cetrifugal (fake) forces.

One of the tricks is trying to get the students to understand that the forces are because of the constantly changing velocity.

There is lots of drawing circles and arrows on the board, and then me swinging a bucket of water around and above my head.

I haven't swung the bucket yet, hopefully it works well :)

Early morning meetings

So I find myself at work way too early in the morning due to staff meetings. We are now meeting for almost an hour before school once a week. That means that we don't get done with that meeting until about 10 minutes before school starts. Which in turn means that if you need to get any work done before school you have to get here very early.

In other news my Physics class will be taking a test on Projectile Motion today. I have a feeling it will either go really well, or really poorly.

Fire Marshall

I have had yet another run in with the State Fire Inspector.

In his report he listed that we didn't have the Science Lab Safety Checklist on file.

But, he never asked anyone if we had one.

I'm pretty sure that "on file" implies that the item in question has been filed away, out of sight. So how he presumed to know that we didn't have one I'm really not sure.

He even came into my room, while I was here, and didn't say or ask anything.

So I filled out the Checklist (for the 3rd time) and my boss told me to post it on the wall near the fire extinguisher.

Now, I'm pretty sure that papers attached to the wall is actually ever MORE of a fire hazard...but apparently I don't know enough about fire to have an opinion...

NaBloPoMo

Well it's Nation Blog Posting Month once again.

I've been so busy that I really forgot about my blog, even if I kept up with Twitter. But, I'm going to try again. I've been inspired by my friends who are taking the challenge of NaNoWriMo (National Novel Writing Month).

So, hopefully I will manage to keep ot up for a whole month!

Why I love Google Apps for Education

I love Google Apps for education because:

• All of my students have an email address that I can find
• I can easily set up a website, permanent or temporary, to put out information for specific groups of students
• I can easily set up websites for my students without worrying about them putting information on the internet uncontrolled
• My students can access their assignments in Google Docs from anywhere with internet
• Students can work on the same document or presentation, at the same time, without having to get together in person
• I can have students turn in most of their homework electronically just by emailing it to me and sharing Google Docs with me
• I can easily add comments into assignments submitted through Google Docs and sent those comments back to the students without using any paper
• I can assign any project I want as long as it can be completed using Google Docs, without worrying about which programs my students have on their computers at home
• I can use Forms for in class activities or tests with real-time feedback

10 Gaps in Education (that don’t get enough press)

{NOT my own writing, sourced from http://ecologyofeducation.net/wsite/?p=1987 Ecology of Education}

Not all gaps are created equal.

The Achievement Gap gets the most press and seems to have the most leverage. But there are a host of others. Read on for a handy dandy guide to 10 Gaps in Education, and then add your own in the comment section.

Legislative Gap

Distance between lawmakers and teachers.

Potential Gap

Difference between a students’ potential and the tasks they are asked to do.

Stimulant Gap

Time between the bottom of one cup of coffee and a refill. Often described as “The Unbearable Gap”.

The Rumsfeld Gap

The schools, teachers, parents, & students we have vs. the schools, teachers, parents, & students we want.

The Billable Gap

When educators daydream about the money they’d make if they could bill their hours. ”65 hrs this week, times 4 weeks this month, times $125 per hour = Cha-Ching!”

The Arm Chair Gap

When folks with no teaching experience suddenly become experts on issues in education after reading an editorial or article.

The Restraint Gap

What a teacher wants to do vs. What a teacher must do when confronted by someone suffering from The Arm Chair Gap.

The Manchurian Gap

Students who are brainwashed to believe that answering test prep questions actually prepares them for entering the work force.

The Coup d’Gap

When policy makers seize the reins of the education debate by scapegoating and alienating teachers. Often characterized by language centered on market terms — accountability, input/output, achievement — and rigor with little or no mention of students, vigor, or relevance.

The Back-to-the-Future Delorean Gap

Often experienced in schools where there is a mix between 19th century teachers/administrators and 21st century technology proponents.

What is your science bias?

All adults who have significant contact with kids pass on some of our own biases to them. Parents and teachers in particular can really easily pass on their like or dislike of a topic to their children/students. If you are a parent or a teacher, what are the biases related to science that you have that you might be passing on? A parent who really liked science in school and thinks it is a fun and interesting can pass on that feeling to their kids. An elementary teacher who thinks that science is difficult and not very useful can pass on that negative feeling to their students.

We pass on so much information that we don't realize. Even the tone of voice we use when we say a certain word can speak volumes to another person. People have a lot of fear of science, they remember it being hard, scary or boring. When people find out I am a science teacher I inevitably hear their horror stories from their high school science classes and teachers. I have had parents at conferences basically imply that it wasn't that important how their kid did in science because science was hard and really not that important for normal people. I'm sure none of these people realize even a little bit how much those attitudes could be affecting their kids.

Women in Science

My first physics class had 40 students in it, and only 5 of us were women. And this was only 12 years ago. I had a TA in a science lab who would just give answers to the women while he would explain things in detail to the men. As if we women wouldn't understand the real science anyways so he just gave us the answer so we would go away.

We like to imagine that the world is equal and fair and for most of us it feels that way. But if you are a women in a male-dominated field you know exactly how far we are form equal and fair. I went in to education, so once I finished college and entered teaching I didn't notice the difference anymore. Lots of science teachers are women, even when there aren't nearly as many women scientists.

And now the American Association of University Women has released a report on the underrepresentation of women in science fields. And people are talking about it, why is that the case? Do women just not like science as much? Or is there more to it than that...?

Bias Called Persistent Hurdle for Women in Sciences - NYTimes.com

Problem Solving

It is amazing to watch a group of students given the same problem and the freedom to solve it however they want. You will see so many different styles of problem solving. Some will sit quietly, thinking and writing down ideas and then go and solve the problem all at once. Others will try many little things and build their solution brick by brick. Some students love to collaborate and brainstorm with others. Other students want to do it all by themselves and resent any outside input. And then some students are completely lost without step-by-step instructions. They have no idea how to approach a problem and work out a solution. Sometimes they are afraid of not doing it right, as if a big problem could only have a single solution. Others have just never been asked to do this kind of problem solving.

Over the years the percentage of kids who don't know how to start problem solving has been getting bigger. And we in education need to figure out what to do about it. In real life students will need to deal with many problems and almost no high-stakes tests.

Speaking Up For Scientists

Very interesting response to Nicholas Maxwell's accusation of scientists "deceiving us and themselves about the nature of science" in the Guardian. It does a good job of explaining the nature of science and scientists see it. It also discusses the problem of the public seeing much of scientific research as unimportant. The look at an experiment that is testing one small idea in one small scenario and they don't see how that could possibly matter. But pretty much all big discoveries come from a bunch of little, seemingly unimportant experiments.

Speaking up for scientists | Philip Strange

Where does your waste go?

My Environmental Science class has an assignment this week to find out where their waste goes. When they flush the toilet or put the trash can on the curb what happens to that stuff? As Americans we have this delusion that it somehow magically disappears. If you ask someone about it they really do know that their old toaster didn't just 'poof!' into nothingness, but we kind of act as if that was what happened. Almost no one can tell you where it all goes after it goes down the drain or into the garbage truck. Is your trash incinerated? Sent to a landfill? Does you waste management company sort to remove recyclable materials? If you put out recycling, do you know how much of it actually ends up being recycled? I would bet that if you asked ten people not a single one would know, unless one of them happened to work for some sort of waste management company.

So, I would like to issue a challenge to all of you. Find out where your waste goes. Email your garbage company and ask them what happens after the truck drives away. Call your sewer company and ask where and how the water (and stuff) is treated and where it eventually ends up.

"Invisibility Cloak" created, no kidding...

So we have known for a long time that the way to make an "invisibility cloak" was to get the rays of light to bend completely around an object. That way we see what is behind that object instead of the object itself. Your eye assumes that light rays travel in a straight line, so the light that comes in to your eye always appears to be coming straight at you. If you bend the light you can trick the eye into thinking things are in a different place than they are.

A really simple example of this is is when you have a straw in a glass of water and it looks like the bottom of the straw is larger and moved to the side. The light bends when it passes form the water to the air. Our eyes think it travels in a straight line so we see it as larger and it a different place than it really is.

Now we have know that this was the way to make an invisibility cloak for a long time, we just haven't been able to actually make that happen.

But now a team of scientists in Germany has done it. They created a structure of crystals that bends lights to hide a small bump of gold. The light rays bend completely around the gold bump, making it invisible. Pretty cool huh?

Read more about it:

Reuters: Scientists hide gold with 3D invisibility cloak

The Associated Press: Cloak of invisibility takes a step forward

What Males Will Do

From PBS: Nature

Quiz: Animal Mating Antics

Which Creatures Have "Game"?

http://www.pbs.org/wnet/nature/episodes/what-males-will-do/quiz-animal-mating-antics/950/

Science and Writing

My students really think that they shouldn't have to write in my class. After all, science isn't writing... And it is very hard to convince them that they need to write in all of their classes.

Because you have to write in all jobs. Even if it is just writing your resume or job application, if you sound silly or stupid you probably won't get the job. If you have to write emails to customers and they are full of mistakes those customers may decide to take their business elsewhere. If you have to write instructions for other employees and they don't make sense, the instructions may not be followed.

You have to be able to express yourself in way that means people understand what you are saying and want to listen what you have to say in the first place.

It's a solid, it's a liquid...it's a non-newtonian fluid!

Ever want to watch someone walk on water? Or at least, on something liquid? This is an awesome video that shows the amazing and bizarre properties of non-newtonian fluids. A non-newtonian fluid acts like a liquid until something puts pressure on it, then it acts like a solid....at least for a little while.



Everything on the video is real, they really are walking, and falling into, a giant tub of this stuff. It is not movie magic. Maybe it is real magic??? Nah, just awesome science.

Cool Video Competition

"It's Elemental"

The Chemical Heritage Foundation will be launching a national video competition in the fall of 2010. It will be part of the International Year of Chemistry 2011. They will be creating an interactive periodic table, where each element has a short, documentary style video. Students all over the country (and the world?) will be creating these videos and submitting them to the competition. The winners will get to go to Heritage Day 2011 where they will meet the judges and attend an award ceremony.

For more information:
http://www.chemheritage.org/classroom/its-elemental/index.html

Pi for everyone!

Happy Pi Day!

Yes, there is a day dedicated to celebrating the wonderful number pi. You all remember pi from math class? And maybe from rotational motion if you took physics? It has been known for a long time and we just keep getting to know it better. It never repeats and as far as we know it goes on forever. It has been calculated to over a trillion decimal places. That is more than you could even hope to count. It is used by scientists, mathematicians, teachers and even the ever reluctant students to calculate more things than you could even imagine. There is at least one thing you use in your daily life that owes it's existence, or at least it's current better-than-it-used-to-be condition to pi.

So I leave you with pi...to 50 decimal places
3.14159265358979323846264338327950288419716939937510

http://www.piday.org/

Since when do names include numbers?

Copper II Sulfate, Lead IV Oxide, Nickel III Hydroxide...What's with the Roman numerals in those names for chemical compound?

Some elements can only have one charge, so you can just use their name without needed to add anything to explain what the charge is. Sodium is always 1+ charge, so you can just name the compounds sodium chloride, sodium oxide, etc.

But some elements can have different charges at different times. Copper is sometimes 1+ and sometimes 2+, so you can't just call something copper oxide. You wouldn't know if that was CuO or Cu2O becuase you wouldn't know what charge to criss-cross. So we use a Roman numeral in the name to show what charge the metal has in this particular substance.

So CuO would be copper II oxide and Cu2O would be copper I oxide. Remember that the Roman numeral doesn't tell us what the subscripts are, they tell us the charge. It's easy to get confused and get the names backwards.

So which elements need these Roman numerals? All of the transition metals except for zinc, cadmium and silver can have more than one charge and need Roman numerals. Those three always have the same charge (silver is 1+ and zinc and cadmium are 2+) so they don't need Roman numerals. Also tin and lead, even though they aren't transition metals, can have 2+ or 4+ charges and need Roman numerals.

Dance Robot Dance!

So I think dancing robots are awesome. So I think you should see some dancing robots...

Super Simple Dancer


Synchronized robots


Japanese Dancing

15 year old ABE lost at sea

Did I mention that ABE is a robot? The "Autonomous Benthic Explorer" has been exploring the ocean all alone for 15 years. It hasn't actually been swimming around for 15 years, it has completed 221 separate dives. It dives down to the seafloor to examine things that people almost never get to see and could explore for as long as a day at a time. It was actually already retired but it's replacement was busy, so they brought the old guy out of retirement for one more dive. They lost communication during the last dive and haven't been able to find ABE since...

News Release : Pioneering Deep-Sea Robot Lost at Sea : Woods Hole Oceanographic Institution

Ionic, covalent, polyatomic...are those even real words?

Listening to a science class can really sound like a foreign language sometimes. It's like people tried to come up with the most confusing words they could think of. And then they used other complicated words to describe the first set of complicated words (like stoichiometry? even the spell-check thinks the word is made up).

And then they want you to name the compounds. And if you try to give them nice names like Buttercup or Hugo they don't give you any credit at all... They want you to follow a very confusing set of rules just to give the simple looking symbols long confusing names. Nitrogen triiodide (which by the way is so explosive it will ignite it touched by a feather) has a name that looks like it can't possibly be real, or at least must be spelled wrong. Who puts two "i"s in a row in a word anyways.

The rules don't really have to be that complicated if you break it down in to pieces. First you have to figure out if the compound you have is ionic or covalent (there are also acids, organic compounds and other special compounds, but that is for a different post).

Remember that an ionic compound is made of one positive and one negative ion. That almost always means one metal and one nonmetal. The only common exceptions are hydrogen, which can act like either a nonmetal or a metal depending on the situation, and the polyatomic ions which are a dead giveaway that you have an ionic compound. Hydrogen you can name like a metal in simple compounds.The polyatomic ions each have a special name, like sulfate or hydroxide, and they keep that name in the compound.

Ionic compounds are named by giving the name for metal followed by the name of the nonmetal.

• Ending of the nonmetal is changed to -ide (oxygen becomes oxide, chlorine becomes chloride)
• Polyatomic ions keep their -ite and -ate endings
• If the metal can have more than one charge[transition metals plus tin and lead, minus silver, cadmium and zinc], include the Roman Numeral for the charge it has in that compound
  

Covalent compounds are made of only nonmetals. Since they can go together in more than one combination (N2O, NO2, N2O3) you can't just use the element names, no one would know which nitrogen oxide you had. So we use prefixes, or extra letters in front of the name, to show how many of that element are in the particular element you are trying to name right now.

So N2O would be dinitrogen monoxide, di- meaning 2 for the two nitrogens, and mono- meaning 1 for the one oxygen. NO2 would be nitrogen dioxide, notice that it isn't mononitrogen. One of the goofy things with the prefixes is that is if the first element is only one, they don't include the mono-, but if the second element is one they do.

All models of the atom you have ever seen are wrong...

So if you know anything about how atoms are actually put together, you know that every model you have ever seen of an atom is wrong. The electrons are too big, too close to the nucleus and usually too planetary-orbit-like. This clip from Nova Science does an excellent job of showing (and fixing) these problems, as well as a few I hadn't thought of before.

http://www.youtube.com/watch?v=5fPOCcj7gEU

In reality the real reason the models are wrong is that there isn't any way to make an accurate model that is of a size and scale that people could actually see and use. That's part of the problem with atoms after all, they are very small and very hard to wrap our brains around.

Welcome Copernicium!

Once upon a time there were some lonely lead atoms in Germany. Then, in February of 1996 some scientists saw that the lead atoms were lonely and decided to introduce them to some friendly zinc atoms. So they loaded up the particle accelerator and played nuclear matchmaker. Much to the scientists delight, the lonely lead atoms and the friendly zinc atoms got along really well. So well in fact that their nuclei combined together to make the very first atoms of brand spanking new baby element, number 112. Baby 112 didn't last very long, only fractions of a second, but it's birth meant the world had yet another new element to name.

And nearly 14 years later little element 112 was still unnamed. Relegated to the temporary name of "ununbium" and confusing symbol of Uub. And now, finally, little 112 has a name! I would like to introduce you to Copernicium!! Named after Nicolaus Copernicus, on February 19, 2010 the IUPAC finally agreed on the name and symbol (Cn because Cp was too easily confused with other scienc-ey symbols).


So let us all welcome yet another element about which high school students will ask "what it is?" and we will say "it the element fill-in-the-blank" and they will say "no, I mean what is it?" and we will say "it is an element that only lasts for few seconds, it isn't anything you have seen or anything" and they will say "then why do we have to know about it?" and we will sigh, and try to remember why we thought it would be fun to be a science teacher.....


Want to find out more?
Element 112 is Named Copernicium (official IUPAC News Brief)
Element 112 Gets a "Planetary" Namesake

Confounding compounds

In chemistry we talk about compounds all the time. We use them to explain other concepts, like types of reactions or separating mixtures. But if you don't know what a compound actually is it would be tricky to know what on Earth we are talking about.

We know that an element is the simplest form of matter. You can't break it down any smaller with doing some kind of nuclear reaction and those tend to not be very compatible will being alive later o do more chemistry. All of the elements are listed on the Periodic Table, and if it isn't on the Periodic Table it isn't an element (sorry Earth, Wind, Water and Fire). Elements have distinct properties that are different from the properties of all of the other elements. That's how we can tell them apart.

But, something special happens when you get two elements to stick together, they become a new thing with completely different properties than either of the elements you started with. For example, sodium is a metal that reacts explosively with water and chlorine is a very poisonous gas. But, when they are stuck together to make sodium chloride they become a white crystal solid that is actually necessary for life.

These elements-stuck-together are compounds. The elements get stuck together in a couple of different ways, but once they are stuck together you can't get them apart by cutting, or sorting, or filtering or any other physical method. You have to do some kind of chemical reaction to get them back apart. That's what makes them different from just mixtures, where the stuff is mixed together but not chemically stuck together. Mixtures you can take apart without needing a chemical reaction.

So sodium carbonate plus silver nitrate yields....what now?

So your chemistry teacher has given you a list of reactions. Well actually they seem to only be half of a reaction, the first half. And they want you to....predict what you will get as products? How on Earth do they expect you to know that? Do they think you are psychic??

It actually isn't as much hocus-pocus as it seems like when you watch the teacher doing the examples on the board. There really are rules you can follow. You do have to know the 5 reactions types first, or you won't be able to get anywhere. Luckily I have already covered that and you can check it out if you need review. Reaction Types, or "What's Going On?" and How Could I Forget Combustion??

So if you start with 2 single elements, it is synthesis and the product will be a simple ionic compound made of those elements. You put the positive one first and use the charges to figure out the subscripts in the formula.

If you start with 1 compound, it is decomposition and the products are the two elements that made up the compound. Remember that diatomic elements get a little subscript 2 when they are alone.

If you start with 1 compound and one element you have a single replacement reaction. If the element is a metal it will switch places with the metal in the compound. If the element is a nonmetal it will switch places with the nonmetal in the compound. You need to check the activity series to see if the reaction will happen. If the element is more reactive (higher on the list) that what it will switch with in the compound the reaction will happen. If it is less reactive the reaction will not happen. (The "No Reaction" ones are easy because you don't have to figure out any formulas or balance anything)

If you start with 2 compounds, it is a double replacement and you will switch the two metals. Each metal will pair up with the other nonmetal or polyatomic ion.

Whenever you make a compound you need to look at the charges to make sure you get the correct formulas.

If you start with a hydrocarbon (something with just hydrogen and carbon) plus oxygen, it is combustion and the products will always be carbon dioxide and water.

So, figure out what type of reaction it is and follow the rules to figure out you will get for products.

How Could I Forget Combustion??

It has been brought to my attention that in my recent post about reaction types I forgot explain the combustion reaction. This should be surprising to anyone who knows a chemistry teacher because most of us went in to this career so we could blow stuff up whenever we want...

Or at least that's part of the reason. But seriously, most science teacher are kind of pyromaniacs. So it seems surprising that I could have forgotten the type of reaction at the very heart of burning stuff!

Combustion reactions (fire!) are a chemical reaction between a hydrocarbon and oxygen. "Hydrocarbon" is a fancy word for a compound made only of carbon and hydrogen in some combination. This includes things most of us have heard of, like methane, propane and butane. They always produce carbon dioxide and water, which makes them easiest of all the reaction types to predict products for.








So, there you are. The last (and most fun) reaction type!

Why do I need to learn this?

As any teacher knows (especially math and science teachers), the most irritating question a student can ask is "Why do I need to learn this?"

This is of course closely followed by "Did we do anything while I was gone?" as the second most annoying question but that is not this post.

So why do we make kids learn all of that stuff anyways? The answer is complicated of course, which is why most students don't actually want to hear it. It is sometimes easier to just tell them that they have to learn it because the politicians say so and they get to decide that stuff.

One of the real reasons is that we teach the increasingly complicated science material in high school is to prepare the students that will be going on to careers in science. If you are going to take a chemistry or physics class in college it is a good idea to take it high school first. And while most high school students are sure they will be professional basketball players or the next American Idol, in reality most of them will get real jobs of some kind. And even some of the students that think they will never take another science class will decide later on that they want to be nurses or engineers.

So in order to prepare the students that will need to take science classes later on, we need to prepare everyone just in case. As you can imagine this answer doesn't really go over well with Mr. future-pro-basketball and Ms. next-American-Idol.


The next reason is that real life as a responsible involved citizen actually requires some basic science knowledge. If someone is trying to sell you something that is supposed to magically remove hard water stains, and you understand the basics of chemical reactions you might be able to decide whether or not to spend $45 dollars for vinegar. And if you know how the water cycle works you will know how to participate in discussions about acid rain or water pollution and how to make informed decisions about voting and policies. We really do need people to understand the science behind all of the tricky political issues that we hear about all of the time.

Somehow students don't actually think this is a good reason, they are pretty sure they can just listen to the television, internet, politician, advertisement, famous person or anyone else and then they don't have to think for themselves.


The last reason, and actually the one I think might be the most important, is that science teaches us how to think. It teaches logical reasoning, problem solving, critical thinking and following directions. Ok, the last one might not actually count as how to think, but I think it is pretty important for people to figure out "Read step 1", "Do step 1", "Read step 2", "Do step 2", etc, etc. This skill seems to be in short supply. And that, along with the other thinking skills are necessary to do a good job no matter what you end up doing. Employers want to hire people who can look at a problem, see multiple ways of solving it, evaluate the possibilities and then solve the problem efficiently. Also, the more you use your brain, the better it works and the longer it works. We know that people who do problem solving and reasoning tasks as they age show less mental deterioration.

This one seems to be the least popular with students, who of course will do whatever they can to avoid thinking...ever.

Earthquake made days shorter. No, really....

So when I saw this headline in someone's Facebook status I was sure it was a link to The Onion (www.theonion.com) which has humorous and satirical news stories. But it was real. Did you know an earthquake could affect the length of a day on Earth?

NASA: Chile Quake Shifted Earth's Axis, Shortened Day

How The Chilean Quake Moved An Entire Planet

Your Day Feel Shorter? Blame Chile's Earthquake

Somehow it kind of shatters a little illusion of constancy that I had. A day is exactly as long a 1 day, that's the whole point. And if the length of a day can change then nothing at all is constant.

Which I really do know. And it isn't as if the change is big enough to make any difference, and it has happened before and it will happen again.

Goodbye 1.26 microseconds of every day...I will miss you! (or not)

Reaction Types, or "What's Going On?"

We all know (or at least those of us who paid even a little of attention in science) that there are chemical reactions happening all around us. Car rusted out? Chemical Reaction. Burned the toast? Chemical Reaction. Fireworks on the 4th of July? Chemical Reaction. Using salt in the water softener? Chemical Reaction.

I'm sure you get the idea. There are 5 basic types that most common reactions can be divided into, synthesis, decomposition, single replacement, double replacement and combustion. These sound a lot more confusing than they actually are. We have reactions where things combine, where things come apart, where things change places (2 types) and where things burn. There are also some fancy, complicated organic reactions, but we aren't going to get in to that.

*Reactions where things combine - Synthesis reactions
When two substances (reactants) combine to form a single new compound (product) that is a synthesis reaction. "Synthesis" just means putting things together, and that is all that is happening in these reaction. These are easy to find because they will only have 1 thing after arrow (1 product).


*Reactions where things come apart - Decomposition Reactions
When a single compound (reactant) comes apart and produces 2 or more simpler substances (products) that is a decomposition reaction. Most of us know that decomposition is when stuff comes apart, like when roadkill on the side of the road slowly gets smaller and smaller over time... You can find these really easily too, just look for reactions with only one thing before the arrow (reactant).

*Reactions where things change places - Single and Double Replacement reactions
When you start out with 2 compounds or with 1 compound and 1 element, something is going to change places with something else. These are called replacement reactions because what basically happens is the stronger of the 2 (more reactive) goes in and replaces the weaker (less reactive). It's important to remember that thing only replaces similar things, so metals switch with other metals, nonmetals with nonmetals. We have 2 names for these because 1 describes the 2-compound reactions and one describes the 1-element-and-1-compound reactions.

Earthquake! What's going on?

Two very large and damaging earthquakes have happened in the last few months and people are asking why so many? Is the world ending? Is it a plot by Aliens to make us crazy and paranoid? Is California about to fell in to the ocean??

While it is possible that one of those things is true, it isn't really very likely. And there are actually large earthquakes every year, it's just that these last 2 have caused a lot of damage and injured or killed a lot of people. Large earthquakes that happen in places where few people live happen every year and we barely hear about it because it didn't impact human lives.

On average there is about 1 earthquake of magnitude 8 or greater every year. That is large enough to cause major damage to structures. We have had 2 so far this year, but there were none in 2008 or 2009. In 2007 there were 4 magnitude 8 or greater earthquakes. There are also 12-14 magnitude 7.0-7.9 earthquakes every year. Those can still cause large amounts of damage, particularly in areas with low quality construction (like Haiti).

Every year there are thousands of earthquakes with smaller magnitudes, up to 15,000 large enough to noticed by people near the epicenter. That is a lot of earthquakes, and most of them we never hear anything about.

Why do Acids have to have funny names anyways?

So why is HCl hydrochloric acid instead of just plain old hydrogen chloride? Well, it is so that Chemistry teachers can torture their students by making them learn yet another different set of rules for naming stuff.

Well not really, but it might seem like that. And you actually have to know how to do it even if the only reason is a tortuous teacher (tortuous: adjective - not direct or straightforward; one who tortures) so you may as well try to get the rules figured out.

The naming rules are all based on the anion in the chemical formula for the acid. Remember the anion is the negative part so it will always come second. And the anion might be just one element, like in HCl or H2S. Or it might be a polyatomic ion like in HNO3 or H3PO4. The ending of the name of the anion tells you how the acid will be named.

Three rules:

1. anion ends in "ide" the acid will be named hydro_____ic acid

• HCl, anion is chloride, acid name is hydrochloric acid
• H2S, anion of sulfide, acid name if hydrosulfuric acid

2. anion ends in "ite" the acid will be named ______ous acid

• HNO2, anion is nitrite, acid name is nitrous acid
• H2SO3, anion is sulfite, acid name is sulfurous acid

3. anion ends in "ate" the acid will be named _______ic acid

• H2CO3, anion is carbonate, acid name is carbonic acid
• H2SO4, anion is sulfate, acid name is sulfuric acid

But WHY do they have these confusing naming rules that seem to just be made up out of nowhere? It's based on an older system of naming that used name suffixes instead of number to give information about the compound. The compounds that we use Roman Numerals to name used to use -ous and -ic endings instead to show which charge the metal had in that compound. The larger of the 2 possible charges got the -ic ending and the smaller got the -ous ending. So instead of Hg II chloride it would have been mercuric chloride.

Anyways, acids still use this older naming system with the different endings telling you what to put in the formula.

Stoichiometry - What??

Now I doubt that many people would start out their blog by talking about stoichiometry, but since that is what inspired the blog in the first place it seems like a good place to start.

Actually I'm pretty sure that 95% of people have no idea what stoichiometry is. They have never even heard the word, or maybe vaguely remember a teacher talking about it once but have since put it out of their mind and moved on to more interesting (and less complicated) things.

So I asked the Internet "What is stoichiometry?" and Wikipedia told me "Stoichiometry is the calculation of quantitative relationships of the reactants and products in a balanced chemical reaction."

Well that clears things up, I'm glad we all understand Stoichiometry now.



...What? You don't actually have any idea what most of those words mean, much less what the sentence means all put together? Hmm...

I guess the first thing you need to know is that stoichiometry is part of chemistry and without some basic background knowledge it won't ever make sense.

• You need to know what elements and compounds are.
  
• You need to know that in a chemical reaction the atoms rearrange into different combinations but that you always end up with the same number of each type of atom that you started wit.
• You need to know that those chemical reactions can be represented on paper by chemical equations use letters, numbers and symbols.
• And you need to understand what a balanced chemical equation is and how to get one.

Now if there are any of those things you don't know already then you are going to have to back up, figure that out and come back. Stoichiometry is confusing enough when you do have all the pieces to start with, it's just silly to try if you don't.

So let's look at that definition again...

"Stoichiometry is the calculation..." So that tells us that we are doing some kind of calculation, which means math. We are starting with some information and then we will be calculating some other, new information.

"...of quantitative..." Well quantitative means numbers, or measurable. That means we are dealing with exact numbers, we can't just say things are getting a little bit bigger or a lot smaller.

"...relationships of the reactants and products..." That's a big chunk all at once but it actually doesn't make sense cut into smaller pieces (trust me). In the chemical reactions we talked about earlier (remember, the stuff you are supposed to know already?) the things we start out with are the reactants and the stuff we have after the reaction happens are the products. We are talking about the relationships between the relationship between the two, how they are related or connected. And remember we are talking quantitative, so this will be a numerical relationship.

"...in a balanced chemical reaction." And those relationships only happen when the equation is balanced. You have to know how many of each substance you are going to have before you can find any of the more complicated relationships.


Practically speaking, stoichiometry is using the information from a balanced chemical equations to make predictions about the amounts of the substances in relationship to each other. It is what lets scientists figure out how much salicylic acid and acetic anhydride to mix together to get 1 kilogram of aspirin. It lets companies know how much material to start with to get the most product with the least waste. It is also what lets scientists figure out a lot of information about new materials.



It also turns out you can learn to do stoichiometry problems without actually understanding what on Earth it all means, and that's what most people do. But that is for another post.


-HeyScienceTeacher