Chemistry Unit- Day 3

Chemistry Unit- Day 3
How Matter Takes Up Space

background information: First we discussed what atoms are and how they come together to form molecules. We compared atoms to letters and molecules to words. We briefly looked at the Periodic Table of Elements.

Activity 1: Marshmallow molecules

Today we had a couple friends over to join in on our chemistry experiments. I gave each kid a sheet with a color key for the marshmallows- white were oxygen, pink was nitrogen, etc... We used Hydrogen, oxygen ,nitrogen, sodium and carbon. The sheet also listed a few common molecules that they would be familiar with.

Then they started building- starting with molecular oxygen. Then to carbon dioxide, water, vinegar, ammonia...

Baking soda is pictured above. We talked about symmetry, but since these guys are all under the age of 9, I didn't go into detail about bonds or any of that.

Then they built their own molecule however they wanted. While they did that we talked about how all the ones they made were different sizes and take up different amounts of space.

Experiments 2 and 3

The next 2 experiments dealt with how mixing different types of matter/molecules effect the volume. We started off adding 25 mL of water and 25 mL of water. We measured out the amounts and they each took a guess as to what the volume would be when they combined the 2 tubes....most guessed 50 mL. Which was correct.

The next part we combined unlike matter/molecules. We measured 25mL of water in one tube and 25 mL of alcohol in a second tube. Then they recorded their guess as to what the final volume would be. Most thought it would still be 50mL, Rylan thought it would be less.

When they combined them the result was just under 50 mL....and we talked about how the alcohol molecules were a different size than the water so they fit together in different ways.

Experiment 4:
This was the second experiment dealing with mixing unlike matter. The kids filled their tube up about half way with salt. Then added water to a couple centimeters above the salt and marked the level on the outside of the tube. Then they took their guess- after shaking would the level of the mixture be above, below or at the line . 2 said at, one said above and one said below. Then they shook

And recorded the result- under the line. And we talked about how shaking evenly distributed with molecules of salt and water, making them take up less space.

Experiment 5: Visualization

This final exercise was to see how the different sized molecules share a set volume. We started off with large "molecules" which were marbles. They took a guess as to how many scoops of marbles it would take to fill the tube. Then they filled them up...and recorded the actual.

Then I asked them if the tube was really full? There was a lot of empty space in between the large molecules. And I asked them to guess how many scoops of "smaller" molecules it would take to fill up the tube the rest of the way. So they started to add scoops of popcorn kernels to the tubes until they were full.

Finally I asked them if it was full again, and then to guess how many scoops of "tiny" molecules it would take to fill the tube. Some said zero some said 20....then they added sand...tapping the tube after each scoop to fill in all the gaps.

Once that was done I asked them what would happen if they had started with the tiny sand. Would they still be able to fit 10-12 marbles in their tube?

They gave it a try- here are Cale's. On the left was 12 scoops of marbles, 6 scoops of popcorn and 8 scoops of sand. On the right he got the 8 scoops of sand and 6 scoops of popcorn but only 1 marble could fit. Since the sand "molecules" could fit so close together the larger marble "molecules" couldn't fit in between them.