In a sample of 100 atoms of Boron, there are 20 atoms of Boron – 10 and 80 atoms of Boron – 11.

(i) Explain why these two forms of Boron are isotopes?
(ii) Calculate the relative atomic mass of Boron.
Isotopes

### 6 thoughts on “Isotopes”

• January 27, 2015 at 6:52 am

i) they have different number of neutrons but similar number of protons and electron
ii) ((80 x 11) + (20 x 10))/100 = 10.2

• February 1, 2015 at 1:57 am

i) should use same instead of similar
ii) Calculation error using the calculator. Answer should be 10.8

• January 28, 2015 at 6:28 am

(i)The two forms of boron have different number of neutrons but same number of protons.
(ii) ((80/100)x11) +((20/100)×10)= 10.8

• February 1, 2015 at 1:58 am

i) Same element with same number of protons and electrons but different number of neutrons.
ii) Correct!

• January 30, 2015 at 4:35 pm

(i)Isotopes are the atoms of the same element but with different number of neutrons but the same number of protons.
(ii) [ (20 x 10) + (80 x 11) ] /100 =9

• February 1, 2015 at 1:59 am

i) Great!
ii) Calculation error using calculator. Answer should be 10.8