Atomic Structure (Edexcel IGCSE Science (Double Award): Chemistry): Exam Questions

The diagram below shows two different atoms of hydrogen.

Which particle is furthest from the centre of each atom?

The diagram shows the electronic configuration of an atom of an element.

Complete the table by giving the missing information about this atom.

This element has three isotopes. The table shows the mass number and percentage abundance of each isotope in a sample of this element.

Calculate the relative atomic mass (A_r) of this element. Give your answer to one decimal place.

The diagram below shows two different atoms of hydrogen.

Which particle is missing from one of the diagrams?

Complete the table to show the relative mass and relative charge of a proton and a neutron. 

Magnesium has three isotopes.

i) State the meaning of the term isotopes.

(2)

ii) The symbol for an atom of one isotope of magnesium is

 Give the number of protons, neutrons and electrons in one atom of this isotope.

 (2)

 number of protons ..............................

 number of neutrons ..............................

 number of electrons ..............................

 iii) A sample of magnesium contains these percentages of the three isotopes.

 Mg‐24 = 79.00%   Mg‐25 = 10.00%   Mg‐26 = 11.00%

 Use this information to show that the relative atomic mass of magnesium is 24.32

 (2)

 iv) One mole of magnesium has a mass of 24.32 g.

 There are 6.022 × 10²³ atoms in one mole.

 Calculate the mass, in grams, of one atom of magnesium.

 Give your answer to 4 significant figures.

 (2)

mass = .............................................................. g

The equation for the reaction between magnesium and oxygen is 

2Mg + O₂ → 2MgO 

Determine the maximum amount, in moles, of magnesium oxide that can be produced from 0.50 mol of magnesium and 0.20 mol of oxygen.

amount = .............................................................. mol

The atomic structure of an unknown element is shown below. 

What is the atomic number and mass number for the unknown element?

State the meaning of the term atomic number.

An atom of element X contains 14 protons, 14 electrons and 15 neutrons.

 i) Which of these is the mass number of this atom?

 (1)

 ii) Explain which group of the Periodic Table element X belongs to.

 (2)

The table shows the composition of a sample of a different element, Y, containing three isotopes. 

 Using information from the table, calculate the relative atomic mass (A_r) of this sample of element Y.  

Give your answer to one decimal place.

 A_r = ..............................

The table shows information about the two isotopes of boron.

The relative atomic mass of this sample of boron is:

The diagram represents an atom of boron.

Use information from the diagram to complete the table. The first row has been done for you.

Boron has two isotopes, boron-10 and boron-11.

A sample of boron contains 18.7% of boron-10 and 81.3% of boron-11.

Calculate the relative atomic mass of this sample of boron.

Which box contains only atoms?

Thallium, Tl, is an element in Group 3 and Period 6 of the Periodic Table.

The atomic number of thallium is 81

How many electrons are there in the outer shell of an atom of thallium?

A thallium ion has a charge of 3+ 

  How many electrons are there in this thallium ion?

A sample of thallium contains two isotopes.

The table shows the mass number and percentage abundance of each isotope in the sample.

 i) Give the number of protons and the number of neutrons in one atom of the thallium-205 isotope.

 (2)

 number of protons: ......................................................................

 number of neutrons:  ...................................................................

 ii) Calculate the relative atomic mass of this sample of thallium.

 Give your answer to one decimal place.

 (3)