Today we got through three different lessons. I started by reviewing atoms and how they are made of protons, neutrons and electrons. I drew a few atoms on the white board showing how the electrons go in shells and how the atoms prefer to have 8 in the second shell. If there is only one electron in that shell the atom would prefer to get rid of it, or if it has 7 electrons in that shell it would really like to have one more. I drew a bunch of different atoms showing how they could share electrons and then both atoms shells would be full and you would have a molecule – covalent bonding. Then I showed them how to draw lewis dot diagrams to show the outer or valenece electrons so we don’t have to draw an atom with the shells each time. The students created a few lift the flap pages in their notebooks using the lewis dot diagrams from Chemistry: Compounds, Bonding & RXNs by Stephanie Elkowitz and we used pages on covalent bonds from Covalent Bonding for Interactive Notebooks by Bond with James – both of which can be bought on Teacherspayteachers.com.
The second thing we did was an electrolysis demonstration, shown above. This is a set up that was purchased from Carolina.com by a fellow homeschooler. You fill the test tubes with water and invert them on to the black stand so that there is no air in the test tubes. When you hook up the wires to a 9V battery the electric current flows and breaks up the water molecules producing hydrogen and oxygen gas. In the photo we used salt water which made for a much more exciting demonstration and you can see the test tube on the right has created quite a bit of gas, almost filling a third of the test tube and this happened in maybe a minute or two.
Lastly, I explained to the students that isotopes were atoms of the same element (same number of protons) but with different numbers of neutrons and therefore slightly different masses. The students then played Atoms & Isotopes that I had downloaded from Elemental Science for free. I had to print out a bunch of playing cards and dig out some pony beads but it seemed to go over well with the kids. The way to win the game is to build all the isotopes on your card. There’s only two different cards, Hydrogen with 3 isotopes for a quick game or Nitrogen with 2 isotopes but a lot more protons, neutrons and electrons to collect before you finish. The kids played a couple rounds in the last 30 minutes of class.
NOVA has a great FREE app, Elements, for iPads where you can build atoms just like in this game. You drag protons, neutrons and electrons. This feature is hidden a bit, from the main menu go to the interactive periodic table and click on the element you want to build. a window pops up with info on the that element and in the top right corner is a green button with Build on it. Click on build and then drag the particles from the bottom of the screen into the center to build the atom. The app keeps a running tab for you on the left side of the screen.