1. Subatomic Particles, Atomic Number and Atomic Mass

2. Subatomic particles Actual e- -1 p+ +1 no mass (g) Relative mass Name
Symbol
Charge
Electron e- -1
1/1840
9.11 x 10-28
Proton p+ +1 1
1.67 x 10-24
Neutron no 1
1.67 x 10-24

3. Structure of the Atom There are two regions: 1. The Nucleus:
With protons and neutrons
Positive charge
Almost all the mass
2. Electron cloud
Most of the volume of an atom
The region where the electron can be found

4. If the atom was the size of a stadium,
If the atom was the size of a stadium,
the nucleus would be the size of:
a marble.

5. Symbols
Contain the symbol of the element, the mass number and the atomic number X
Mass
number
Atomic
# protons
+ # neutrons
mass number
# protons

6. The mass number = # p + # n
The atomic number = #p
In a neutral atom the #e = # p

7. F Symbols 19 9 Find the number of protons number of neutrons
Symbols
Find the
number of protons
number of neutrons
number of electrons
Atomic number
Mass number = F 19 9 = = = =

8. F Symbols 19 9 Find the number of protons number of neutrons
Symbols
Find the
number of protons
number of neutrons
number of electrons
Atomic number
Mass number
= 9 + F 19 9
= 10
= 9
= 9
= 19

9. Br Symbols 80 35 Find the number of protons number of neutrons
number of electrons
Atomic number
Mass number = = = Br 80 35 = =

10. Br Symbols 80 35 Find the number of protons number of neutrons
number of electrons
Atomic number
Mass number
= 35
= 45
= 35 Br 80 35
= 35
= 80

11. Ions
In an ion – a charged particle the charge can be either + or -. The # of protons and neutrons remains the same. It is only the electrons that are gained or lost to create the charge
Mass number = #p + #n
For an ion the #e ≠ #p
adding an electron produces a negative ion
Subtracting an electron produces a + ion

12. Na Symbols 23 11 Find the 1+ number of protons number of neutrons
number of electrons
Atomic number
Mass number = Na = 23 1+ = 11 = =
Sodium ion

13. Na Symbols 23 11 Find the 1+ number of protons number of neutrons
number of electrons
Atomic number
Mass number
= 11 Na
= 12 23 1+
= 10 11
= 11
= 23
Sodium ion

14. http://www. webelements. com/webelements/elements/media/nearingzero/Na

15. Symbols
If a neutral atom of an element has 78 electrons and 117 neutrons what is the
Number of protons
Atomic number
Mass number
Complete symbol

16. Symbols
If a neutral atom of an element has 78 electrons and 117 neutrons what is the
Number of protons = 78
Atomic number = 78
Mass number = = 195
Complete symbol = Pt