1. -Atomic Number
  N  
-Element Symbol
-Atomic Mass Number
In neutral atom the number of protons = the number of electrons

2. To find the number of neutrons in an atom you –
1. Round the bottom number to the nearest whole number
2. Subtract the atomic number from the atomic mass number. (You will always subtract the smaller number on top from the larger bottom number)

3. Calculating Neutrons 11H = 1 - 1 = 0 neutrons
1123Na = = 12 neutrons
23 (protons and neutrons)
- 11 just protons
12 neutrons

4. Element
Number of Protons
Mass Number
Number of electrons
Atomic Number
Number of Neutrons
Hydrogen 1
Helium
Carbon
Nitrogen
Oxygen
Cobalt
Copper
Iron
Uranium
Krypton

5. Properties of Subatomic Particles
Symbols
Relative Electric Charge
Mass Number
Relative Mass (AMU)
Actual Mass (Kg)
Electron
e--- , e
-- 1 x
Proton
p H +1 1
1.673 x
Neutron
N0 , o1n
1.675 x

6. Remember— Protons are Positive Electrons are negative
Neutrons are neutral

7. 29 Cu 63.55 -Atomic Number = number of protons
-Element Symbol
-Atomic Mass Number= number of protons PLUS neutrons
Isotopes are atoms that have the same number of protons as another atom but have different number of NEUTRONS

8. Isotopes are atoms that have the same number of protons as another atom but have different number of NEUTRONS

9. Uses of Isotopes Medical tracers- Tc (43) used in bone scans
Carbon-14 “radioactive carbon dating” to estimate age of very old stuff.