Daniel R. Barnes Init:10/2/09

... look at a drawing of an atom and determine its element, its atomic number, its mass number, and its electric charge. “SWBAT = “Students will be able to”

This lesson is the reverse of the atom drawing lesson. In the atom drawing lesson, I gave you a chemical symbol, a mass number (sometimes), and an electric charge (sometimes), and from that you were supposed to draw an atom. In this lesson, I will show you a drawing of an atom, and you will need to determine its element, its atomic number, its mass number, and its electric charge.

= -1 = 0 Before we get started with identifying full atoms, we’d better make sure you know all the parts, first. = “proton” = “neutron” = “electron” electric charge = +1 electric charge electric charge

The clump in the center of the atom is called the “nucleus”. The big circles surrounding the nucleus like the layers of an onion are called “shells”. WARNING: What one person means by “shell” or “energy level” may be different than what other people mean.

ATOM IDENTIFICATION Okay. Let’s do what we came here to do.

ATOM IDENTIFICATION First, identify what element the atom is by counting the number of protons in the nucleus. This atom has five protons, so its atomic number is five. Now that we know its atomic number, we can look on the periodic table to figure out what element it is.

Element number five is...boron.

ATOM IDENTIFICATION This is a boron atom, so we can write the symbol for boron... B Next, we’re going to write the atomic number of the atom in the lower left subscript area. You don’t really need to do this most of the time, because all boron atoms automatically have an atomic number of five, but we’re going to do it just for kicks. 5

ATOM IDENTIFICATION In other words... Next, we need to figure out the mass number, which is the total number of things in the nucleus. Mass # = # of protons + # of neutrons Mass # = = B 5

ATOM IDENTIFICATION After all, neutrons are neutral. Finally, we need to calculate the electric charge of the atom. The protons and electrons matter for this, but not the neutrons. Electric charge = # of protons - # of electrons Electric charge = 5 – 4 = 1 = +1  “+” + 11 B 5

Let’s do a few more to see if you’ve got it.

10 Atomic number is 10Element is neon Ne 7 Mass number = = Electric charge = 10 – 6 = 4 = “4 + ” 4+

10 Atomic number is 10Element is neon Ne 4 Mass number = = Electric charge = 10 – 2 = 8 = “8 + ” 8+

8 Atomic number is 8Element is oxygen O 2 Mass number = = Electric charge = = 4 = “4 + ” 4+

9 Atomic number is 9Element is fluorine F 3 Mass number = = Electric charge = = -1 = “-” -

7 Atomic number is 7Element is nitrogen N 3 Mass number = = Electric charge = = -3 = “3-” 3-

2 Atomic number is 2Element is helium He 9 Mass number = = Electric charge = = -8 = “8-” 8-

4 Atomic number is 4Element is beryllium Be 7 Mass number = = Electric charge = 4 – 8 = -4 = “4-” 4-

6 Atomic number is 6Element is carbon C 6 Mass number = = Electric charge = 6 – 0 = 6 = “6+” 6+

1 Atomic number is 1Element is hydrogen H 0 Mass number = = Electric charge = 1 – 5 = -4 = “4-” 4-

5 Atomic number is 5Element is boron B 3 Mass number = = Electric charge = 5 – 0 = +5 = “5+” 5+

8 Atomic number is 8Element is oxygen O 6 Mass number = = Electric charge = = 0 = “”

3 Atomic number is 3Element is lithium Li 1 Mass number = = Electric charge = = -7 = “7-” 7-

More practice atoms to come later...