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This question is about atomic structure, isotopes, and the periodic table.

Gallium ( $Ga\text{Ga}$ ) is a metal that has more than one stable isotope.

Define the term 'isotopes' in terms of subatomic particles.

[2]

Table 1 shows the mass numbers and percentage abundances of the two stable isotopes found in a specific sample of gallium.

Table 1

Mass number	Percentage abundance (%)
69	62
71	38

Calculate the relative atomic mass ( $A_r$ ) of gallium in this sample.

Give your answer to 1 decimal place.

[2]

Gallium is located in Group 3 of the modern periodic table.

Determine the number of electrons and the number of neutrons in a neutral atom of the isotope $3171Ga{}^{71}_{31}\text{Ga}$ .

[2]

What is the most likely formula of a gallium(III) ion?

Select one option:

$Ga3−\text{Ga}^{3-}$
$Ga+\text{Ga}^{+}$
$Ga2+\text{Ga}^{2+}$
$Ga3+\text{Ga}^{3+}$

[1]

Gallium was discovered in 1875, six years after Dmitri Mendeleev published his first periodic table.

Give two reasons why the discovery of gallium helped scientists to accept Mendeleev's periodic table.

[2]

A simple model of the atom, symbols, relative atomic mass, electronic charge and isotopes Questions

Practise AQA GCSE Chemistry A simple model of the atom, symbols, relative atomic mass, electronic charge and isotopes with exam-style questions for Foundation and Higher tier. 64 questions covering Atoms, elements and compounds, Mixtures, The development of the model of the atom (common content with physics), Relative electrical charges of subatomic particles, Size and mass of atoms, Relative atomic mass, and Electronic structure, matched to the AQA GCSE Chemistry (8462) specification and written in Paper 1 and Paper 2 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.