1. ATOMS
Standard C-2 Students will demonstrate an understanding of atomic structure and nuclear processes.

2. What is MATTER? Matter is anything with a mass and volume
Matter is made of things called ATOMS.

3. Matter Can Be a PURE substance or a MIXTURE
Elements
Cannot be decomposed into simpler substances
Gold
Compounds
Can be decomposed into simpler substances by chemical change
Carbon dioxide, CO2

4. Matter Can Be a PURE substance or a MIXTURE
Elements:
Compounds:
Individual elements represent individual atoms
Compounds are molecules
Molecules are made up of two or more atoms

5. ATOMS
An atom is the smallest particle of an element that retains its identity in a chemical reaction
Made up of 3 subatomic particles
Protons
Neutrons
Electrons

6. Protons p+
Positively charged
Relative charge 1+
Found in nucleus

7. Neutrons n0 No charge Approximately the same mass as proton
Found inside the nucleus

8. Electrons e- Negatively charged Relative charge 1-
Found in electron cloud
Found in different energy levels
n= 1, 2, 3, …

9. Reading a Periodic Table
Atomic #
Element
Atomic Mass

10. Atomic Mass - Atomic Number
Is the number of PROTONS
This is also the number of ELECTRONS
Is the total number of PROTONS and NEUTRONS
# of Neutrons
Atomic Mass - Atomic Number

11. APE
Atomic Number
Equals
Protons
Electrons

12. MAN
Mass
Minus
Atomic Number
Equals
Neutrons

13. Practice How many protons does carbon have?
How many neutrons does carbon have?
12 – 6 = 6 neutrons
How many electrons does carbon have?
6 electrons

14. Practice How many protons does chlorine have?
How many electrons does chlorine have?
17 electrons
How many neutrons does chlorine have?
35 – 17 = 18 neutrons

15. Isotopes
Is an element that has a different number of neutrons and different atomic mass.

16. Hydrogen Isotopes The most common type of hydrogen is called protium
Nucleus only consists of one proton and zero neutrons.

17. Bohr Model Bohr model places electrons in energy levels
Electrons orbit around nucleus like the planets around the sun
n=4
n=3
n=2
n=1
nucleus

18. # of e- = 2(n2) n = energy level
nucleus

19. # of e- = 2(n2) n = energy level
2(12) = 2 electrons in the 1st energy level
n = 3
2(32) = 18 electrons in the 3rd energy level

20. Carbon Bohr Model Carbon has 6 electrons Nucleus 6 electrons -2

21. Chlorine
17 electrons -2
=15 electrons -8
=7 electrons
Nucleus