1. What is an ISOTOPE?
EXAM PRACTICE
Q. Explain what is meant by the term isotope.
Learn this:
Isotopes are different forms of the same element, which have the SAME number of PROTONS but DIFFERENT numbers of NEUTRONS

2. TASK 1
Spot the Pair
You will be shown 4 atoms
Identify the 2 isotopes

3. protons
neutrons

4. 35 Da 14
35 Da 15
32 Da 16
32 Da 15

5. 47 60 46 47 60 47 57 48 57 No. of electrons No. of neutrons
No. of protons 47 60 46
No. of electrons
No. of neutrons
No. of protons 47 60
No. of electrons
No. of neutrons
No. of protons 47 57
No. of electrons
No. of neutrons
No. of protons 48 57

6. Gymnium-95 Gymnium-96 Gymnium-96 Gymnium-98 Electrons:48 Neutrons: 47
Protons:48
Gymnium-98
Neutrons:47

7. Task 2
Complete the worksheet on ISOTOPES

8. Look at your periodic table
Look at your periodic table. The atomic masses are all whole numbers except for….
35.5 Cl
Chlorine 17
The relative Atomic Mass of Chlorine is recorded as 35.5.
How many neutrons does it have?
35.5 – 17 = 18.5
You can’t have half a neutron. So how can this be explained?
63.5 Cu
Copper 29

9. What are the Numbers all About?
75% of the Chlorine in existence is Cl35
25% of the Chlorine in existence is Cl37 35 35 35 35 35 35 35 35 35 35
ISOTOPES 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 37 37 37 37 37 35 35 35 35 35 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37

10. What are the Numbers all About?
Total number of protons & neutrons in a specific isotope
From calculations involving all isotopes
Relative
Atomic
Mass (Ar)
Mass Number 35 Cl 17 37 Cl 17
35.5 Cl 17
Atomic Number (Proton Number)

11. What are the Numbers all About?
Total number of protons & neutrons in a specific isotope
Relative
Atomic
Mass (Ar)
From calculations involving all isotopes
Mass Number 64 Zn 30 66 Zn 30
65.409 Zn 30 67 Zn 30 68 Zn 30 70 Zn 30

12. Isotopes of hydrogen Protium Deuterium Tritium 1 proton,
0 neutron, 1 electron
1 proton,
1 neutron, 1 electron
1 proton,
2 neutron, 1 electron

13. 1 H
Hydrogen has RAM of 1 because 99% of the hydrogen atoms on earth are Hydrogen-1
Bromine has RAM of 80 as it is found here as 50% Bromine-79 and 50% Bromine-81. 80 Br 35

14. How to calculate R.A.M (Ar)
Copper has two main isotopes.
69% are Copper-63
31% are Copper-65
Can you guess what the R.A.M will be close to?
RAM = (mass no 1 x % abundance 1) + (mass no 2 x % abudance 2) 100

15. The periodic table states that the Relative Atomic Mass (Ar) of Boron is 11
Boron has two naturally occurring isotopes.
80% of all Boron is B11 (6 neutrons)
20% of all Boron is B10 (5 Neutrons)
Calculate the average relative atomic mass of Boron.

16. The periodic table states that the Relative Atomic Mass (Ar) of Magnesium is 24
Magnesium has three naturally occurring isotopes.
79% of all Magnesium is Mg24 (12 neutrons)
11% of all Magnesium is Mg25 (13 Neutrons)
10% of all Magnesium is Mg26 (14 neutrons)
Calculate the average relative atomic mass of Mg