1. 1. Atomic Structure
Objectives: Describe properties of subatomic particles Recall how element / nuclear symbols work Explain the existence of isotopes.

2. The atom model from GCSE:

3. The subatomic particles from GCSE:
Relative mass
Relative charge
Proton
Neutron
Electron

4. The subatomic particles from GCSE:
Relative mass
Relative charge
Proton 1 1+
Neutron
Electron
1/2000 1-

5. THE STRUCTURE OF ATOMS
Atoms consist of a number of fundamental particles,
the most important are ...
Mass / kg
Charge / C
Relative mass
Relative charge
PROTON
NEUTRON
ELECTRON

6. Subatomic particles 1 +1 1 -1
Atoms consist of a number of fundamental particles,
the most important are ...
Mass / kg
Charge / C
Relative mass
Relative charge
PROTON
NEUTRON
ELECTRON 1 +1
1.672 x 10-27
1.602 x 10-19 1
1.675 x 10-27 1
1836 -1
9.109 x 10-31
1.602 x 10-19
Calculate the mass of a carbon-12 atom; it has 6 protons, 6 neutrons and 6 electrons

7. Subatomic particles 1 +1 1 -1
Atoms consist of a number of fundamental particles,
the most important are ...
Mass / kg
Charge / C
Relative mass
Relative charge
PROTON
NEUTRON
ELECTRON 1 +1
1.672 x 10-27
1.602 x 10-19 1
1.675 x 10-27 1
1836 -1
9.109 x 10-31
1.602 x 10-19
Calculate the mass of a carbon-12 atom; it has 6 protons, 6 neutrons and 6 electrons
6 x x x x x x =

8. Subatomic particles 1 +1 1 -1
Atoms consist of a number of fundamental particles,
the most important are ...
Mass / kg
Charge / C
Relative mass
Relative charge
PROTON
NEUTRON
ELECTRON 1 +1
1.672 x 10-27
1.602 x 10-19 1
1.675 x 10-27 1
1836 -1
9.109 x 10-31
1.602 x 10-19
Calculate the mass of a carbon-12 atom; it has 6 protons, 6 neutrons and 6 electrons
6 x x x x x x = x kg

9. Mass number and atomic number
Atomic Number (Z)
Mass Number (A)

10. Mass number and atomic number
Atomic Number (Z) Number of protons in the nucleus of an atom
Mass Number (A) Sum of the protons and neutrons in the nucleus

11. Mass number and atomic number
Atomic Number (Z) Number of protons in the nucleus of an atom
Mass Number (A) Sum of the protons and neutrons in the nucleus
Mass Number (A)
PROTONS + NEUTRONS Na 23 11
Atomic Number (Z)
PROTONS

12. THERE WILL BE 12 NEUTRONS IN THE NUCLEUS
Mass number and atomic number
Atomic Number (Z) Number of protons in the nucleus of an atom
Mass Number (A) Sum of the protons and neutrons in the nucleus
Mass Number (A)
PROTONS + NEUTRONS
THERE WILL BE 12 NEUTRONS IN THE NUCLEUS
23 – 11 = 12 Na 23 11
Atomic Number (Z)
PROTONS

13. Atoms and Ions What is an ion? How is a negative ion made?
How is a positive ion made?
Describe: Br-
Describe Mg2+

14. Mass number and atomic number
Protons
Neutrons
Electrons
Charge
Atomic Number
Mass Number
Symbol A 19 21 B 20 40 C + 11 23 D 6 E 92
235 F 13 G 16 2- H
27Al3+

15. Mass number and atomic number
Protons
Neutrons
Electrons
Charge
Atomic Number
Mass Number
Symbol A 19 21 40
40K B 20
40Ca C 11 12 10 + 23
23Na+ D 6
12C E 92
143
235
235U F 7 13
13C G 16 18 2- 32
32S2- H 14 3+ 27
27Al3+

16. Isotopes
Definition:

17. Isotopes
Definition:
Isotopes of an element are atoms with the same number of protons, but different numbers of neutrons
Chemical properties of isotopes are identical
Physical properties (such as density) can differ

18. Isotopes
Example: Chlorine-35 and Chlorine-37

19. Isotopes - calculations
There are two common isotopes of chlorine. Calculate the average relative atomic mass of chlorine atoms
Method 1 Three out of every four atoms will be chlorine-35
Average = = 35.5 4
Method 2 Out of every 100 atoms 75 are 35Cl and are 37Cl
Average = (75 x 35) + (25 x 37) = 35.5
100
Protons
Neutrons % 35 Cl 17 18 75 37 20 25

20. Questions (actual exam ones)
Hydrogen, deuterium and tritium are all isotopes of each other.
Identify one similarity and one difference between these isotopes.
Deuterium can be written as 2H. Determine the number of protons, neutrons and electrons in a neutral deuterium atom.
Write a nuclear symbol for tritium, given that it has 2 neutrons.
2. A certain atom X has one less proton and two more neutrons than K. What are its atomic number and mass number?
Explain in terms of sub atom particles, why C-12 and C-14 are isotopes