This question is about atomic structure and the periodic table - AQA - GCSE Chemistry - Question 2 - 2021 - Paper 1
Question 2
This question is about atomic structure and the periodic table.
Gallium (Ga) is an element that has two isotopes.
02.1 Give the meaning of 'isotopes'.
You should ... show full transcript
Worked Solution & Example Answer:This question is about atomic structure and the periodic table - AQA - GCSE Chemistry - Question 2 - 2021 - Paper 1
Step 1
Give the meaning of 'isotopes'.
96%
114 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons. This results in isotopes having different atomic masses.
Step 2
Calculate the relative atomic mass (A_r) of gallium.
99%
104 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
To calculate the relative atomic mass, we can use the formula:
Ar=100(69×60)+(71×40)
This gives:
Ar=1004140+2840=69.8
Thus, the relative atomic mass of gallium is 69.8.
Step 3
Give the numbers of electrons and neutrons in an atom of the isotope $^{69}_{31}Ga$.
96%
101 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
For the isotope 3169Ga, the number of electrons is 31, and the number of neutrons is 38.
Step 4
What is the most likely formula of a gallium ion?
98%
120 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The most likely formula of a gallium ion is Ga2+.
Step 5
Give two reasons why the discovery of gallium helped Mendeleev's periodic table to become accepted.
97%
117 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Gallium fitted in a gap that Mendeleev had left.
The properties of gallium were predicted correctly by Mendeleev, matching the rest of the group.
