1. The three SUBATOMIC PARTICLES are
Proton
Electron
Neutron

2. PROTON Symbol charge location p+ +1 Mass in the nucleus
same as neutron

3. ELECTRON Symbol charge Location Mass e- -1 outside the nucleus
tiny; 1/2000 of a proton

4. Force inside atoms
Electrons are bound to the nucleus by the attractive force between electrons (-) and protons (+).

5. NEUTRON
Symbol n charge 0
Location in the nucleus
Mass same as proton

6. Pb Element Card 82 Lead 207.2 Atomic Number Element Symbol
Element Name
Atomic Mass

7. ATOMIC NUMBER – equals the number of protons in an atom of an element
Element Card
Atomic Number 82 Pb
Lead
207.2

8. Atomic Number Number of Protons
ATOMIC NUMBER – equals the number of protons in an atom of an element
Element
Atomic Number
Number of Protons
Carbon 6
Calcium 20
Silver 47

9. BALANCING CHARGE
* the +1 charge of a proton exactly equals the -1 charge of an electron
* all atoms are electrically neutral
* in an atom the number of protons equals the number of electrons

10. Element
Atomic Number
Number of Protons
Number of Electrons
Oxygen 8
Copper 29
Gold 79

11. MASS NUMBER – the sum of the protons and neutrons in the nucleus82 Pb
Lead
207.2
Atomic Mass

12. 19 20 6 27 13 66 30 The number of neutrons =
mass number – atomic number
Mass Number
Number of Protons
(Atomic Number)
Number of Neutrons 19 20 6 27 13 66 30

13. ISOTOPES – atoms of the same element have different numbers of neutrons
Mass Number
Atomic Number
Number of Protons
Number of Neutrons
Oxygen - 16 8
Oxygen - 17
Oxygen - 18

14. To summarize isotopes:
They are atoms of the same element They have the same number of protons . They have different number of neutrons . They have different mass numbers. They have the same chemical and physical properties.