Chemistry Class - Atomic Structure - Homeschool Science Chemistry

This is the second lesson in the homeschool science Chemistry Class I am putting together for elementary and middle school aged students! Today's topic is Atomic Structure! Click HERE to see all the other lessons too!

These lessons are designed to be "open and go," so you can grab your supplies (have your kids help!), print the lesson and read it as you go or just read from a tablet or laptop with your kids!

* Periodic Table
* about 25 pieces of 3 small food items for each child (I used cut dried fruit, chocolate chips, and peanuts. In the past I've used different colors of mini-marshmallows, but I now have a child who can't have sugar. Raisins also work great!)

At the end of this lesson, students will be able to...
1- Explain what an atom is.
2- List the 3 subatomic particles and the charge each of them have.
3- List the number of protons, neutrons, and electrons of any atom they can find on the Periodic Table.
4- Identify how many electrons are in the first 3 energy levels of an atom.


First let your students cut out the pieces on the atomic structure printout.

Read or Discuss: What is an atom? Atoms are the building blocks of matter. Everything is made from atoms. One atom of oxygen is the smallest bit of oxygen that still behaves like oxygen--we say that it retains the properties of oxygen because, even though it is tiny, it still behaves like oxygen. What would happen if we cut one atom of oxygen into smaller pieces?

We would find that there are particles inside the atom! These subatomic particles (particles smaller than an atom) no longer behave like oxygen, they behave like individual little tiny particles. There are 3 important subatomic particles that we're going to look at.

The two biggest subatomic particles are in the "nucleus," or center of the atom. Place the large white circle on the table. This white circle represents the nucleus. It is where all the "protons" are. Protons are one of the biggest subatomic particles. They have a positive charge. Place 2 red protons inside the nucleus. 

Think about the positive ends of two magnets. What happens if you bring them close together? They repel each other! So what do you think two protons would do if they were all by themselves together? Also repel!

We don't want our atom ripping itself apart, so it's good that we have "neutrons" in the nucleus too. Neutrons have no charge, and they seem to act like glue, keeping the protons close to each other. Place two blue neutrons inside the nucleus also. Neutrons are about the same size as protons.

The final subatomic particles that we need to know about are "electrons." Place two yellow electrons just outside the nucleus. Electrons have a negative charge and are about 1800 times smaller than protons and neutrons, so obviously these are not to scale. They fly around the nucleus in an area we call "energy levels." The lowest energy level, closest to the the nucleus, can only hold two electrons.  When we have the same number of protons and electrons, the whole atom has no charge. If we had more electrons than protons, the whole atom would have a negative charge. if we had more protons than electrons the whole atom would have a positive charge.

So now we have an atom with protons, neutrons, and electrons! How many protons are in this atom we've made? (2) Let's look at the periodic table and figure out what atom we've just illustrated. 

Pull out a periodic table. Each different element on the periodic table has a square with information about it. Near the top you can usually find the "atomic number." This very important number tells you how many protons are in the atom. So what atom did we just diagram? Helium!

The atomic number also tells you how many electrons you have in an atom with no net charge (also called neutral). Remember a neutral atom has the same number of protons and electrons. Do any of the atoms on the periodic table have the same atomic number? No. The atomic number defines or tells you what atom you are looking at. So if we toss a third proton in our little atom, we no longer have helium. What do we now have? Lithium!

The other number in each element's square on the periodic table is the atomic weight. Electrons are so small they practically weigh nothing, so the weight is basically made by adding the protons and neutrons together.  If your periodic table has a large decimal number for the weight, round to the nearest whole number. 

Let's look at helium again. It has an atomic number of 2 (so we know there are 2 protons and 2 electrons), and an atomic weight of 4 (so we can figure out the number of neutrons by subtracting 4-2=2).

Let's build lithium together. How many protons and electrons does it have? 3. (The atomic number is 3, and that tells you how many protons and electrons it has.) Place 3 protons in the nucleus. Place 2 electrons close to the nucleus in an imaginary first energy level. Place the 3rd electron a little farther from the nucleus in an imaginary 2nd energy level.  Electrons like to travel in pairs, and they fill the first energy level first, then the second, then the third. There are more energy levels, but we're not going to worry about the arrangement of them until high school.  Finally, how many neutrons does lithium have? 4. (The atomic weight is 7. 7-3=4.) Place 4 neutrons in the nucleus with the protons.

This atom has the same number of protons and electrons, so it doesn't have any charge. But do you see that one lone electron farthest away from the nucleus? It is not too hard to rip that electron off. Pull the electron off. Now do we have more electrons or protons? Protons. So is the atom positively or negatively charged? Positively.

It turns out that any atom with a charge (either positive or negative) becomes "sticky," or very likely to react with another atom...especially one with the opposite charge!

Look at your periodic table. Everything in the first column has one lone electron, so everything in this column is very fact, a piece of sodium (#11) the size of an apple can make an explosion big enough to tear a house apart if you just drop it in water!

Now look at the last column, the one with helium. Everything in this column, or "family," is very stable. The outer energy level is full and the electrons are all traveling in pairs, so these elements tend to not react. They are also all gasses, so we call them "noble gasses!"

It's time to make some more atoms! 

Use the printout as a guide. Choose an atom with an atomic number between 4 and 28. Choose a food item to represent protons, a different food for neutrons, and a third food for electrons. Use a periodic table to calculate the number of protons, electrons, and neutrons for an atom. Then "build" that atom. 

If you want to remove the subatomic particles you can build more than one model.

When you finish, eat the subatomic particles!

Review/Final Discussion:

1- What is an atom?
2- What are 3 subatomic particles? What charge does each particle have?
3- How many electrons can fit in an atom's first energy level? Second? Third?
4- How many protons are in calcium? What is calcium's atomic number? How many neutrons are in calcium? How many electrons? How many energy levels does calcium need for its electrons?


This is the second lesson in my Atoms & Molecules Chemistry Class for homeschoolers!  Click HERE to get the rest!

And if you're looking for more homeschool unit studies, be sure to check out our growing collection here!

Happy Educating,
Carla & the kids who don't sit still!

And if you're looking for more homeschool unit studies, be sure to check out our growing collection here!

Happy Educating,
Carla & the kids who don't sit still!