Atomic Structure (Edexcel GCSE Chemistry): Exam Questions

The atomic structure of an unknown element is shown below. 

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

Atoms contain electrons, neutrons and protons.

i) Draw one line to link each particle to its correct relative charge. (2)

ii) Which of the following is the relative mass of a proton?

(1)

A 0
B
C 1 
D -1

Argon is in group 0 of the periodic table. Identify, using the periodic table, which of these elements is in the same period as argon.

Figure 4 shows the atomic number and mass number of two isotopes of argon.

Figure 4

Describe the structure of an atom of argon-38 and of an atom of argon-40.

As the atomic model developed, protons, neutrons and electrons were discovered. 

What was the correct order of discovery?

Chlorine has an atomic number of 17.

Figure 3 shows the arrangement of electrons in an atom of chlorine.

Figure 3

i) What is the electronic configuration of this atom?

(1)

ii) Explain, using Figure 3, why chlorine belongs to group 7 of the periodic table.

(2)

The nucleus of an atom is made up of protons and neutrons. Atoms of chlorine contain 17 protons.

Figure 4 shows some information about a proton, a neutron and an electron.

Figure 4

i) Explain, using the information in Figure 3 and Figure 4, why atoms of chlorine have no overall charge.

(2)

ii) Atoms of chlorine-37 have a mass number of 37. Calculate the number of neutrons in atoms of chlorine-37.

(1)

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

iii) There are two isotopes of chlorine, chlorine-35 and chlorine-37. Explain the meaning of the term isotopes.

(2)

Chlorine–35 and chlorine–37 are isotopes. 

Which statement describes an isotope?

Higher Tier Only 

Titanium and iron are examples of transition metals.

Figure 6 shows the percentage abundance of each isotope in a sample of titanium.

Figure 6

Calculate the relative atomic mass of titanium in this sample.

relative atomic mass = ......................................

Iron, when heated in air, reacts with oxygen to form iron oxide.

i) This reaction is an example of (1)

ii) The equipment shown in Figure 7 can be used to find the mass of oxygen that combines with iron.

Figure 7

Describe how the equipment shown in Figure 7 could be used to find the mass of oxygen that combines with 0.500 g of iron wool in a crucible and lid of known mass.

(3)

2.24 g of iron combines with 0.96 g of oxygen to form an oxide of iron.

Determine the formula of this oxide of iron and use it to complete the balanced equation.

(relative atomic masses: Fe = 56.0, O = 16.0)

You must show your working.

balanced equation for the reaction is

................ Fe + ................O₂ → ................................................

An atom has no overall charge because there are the same number of:

This question is about some of the elements in groups 1 and 2 of the periodic table.

The atomic number of lithium is 3. The mass number of a lithium atom is 7. Which row of the table shows the number of protons, neutrons and electrons in an atom of lithium-7?

Lithium, sodium and potassium are in group 1 of the periodic table.

State, in terms of the electrons in their atoms, what the atoms of lithium, sodium and potassium have in common.

Magnesium has atomic number 12.

Magnesium exists as magnesium-24, magnesium-25 and magnesium-26 atoms.

Explain, in terms of protons and neutrons, why these atoms are isotopes of magnesium.

Magnesium and calcium are in group 2 of the periodic table. They are less reactive than the metals in group 1.

Calcium reacts with water to form calcium hydroxide, Ca(OH)₂, and hydrogen, H₂.

Ca (s) + 2H₂O (l) → Ca(OH)₂ (s) + H₂ (g)

Describe what would be seen when a piece of calcium is dropped into a container of water.

Magnesium reacts very slowly with cold water but it reacts faster with steam, H₂O, to form magnesium oxide, MgO, and hydrogen.

Write the balanced equation for the reaction between magnesium and steam.

The electronic configurations of magnesium and calcium are

magnesium 2.8.2
calcium 2.8.8.2

When magnesium and calcium react with water they form positive ions.

Suggest an explanation, in terms of their electronic configurations, why calcium is more reactive than magnesium.

A sample of calcium bromide contains 0.2 g calcium and 0.8 g bromine by mass.

Calculate the empirical formula of calcium bromide. (relative atomic masses: Ca = 40, Br = 80)

Which statement best describes the structure of an atom? 

An atom of potassium has atomic number 19 and mass number 39.

i) Give the electronic configuration of this potassium atom. (1)

ii) This potassium atom forms the ion K⁺. Which row shows the number of protons and the number of neutrons in this potassium ion, K⁺? (1)    

Potassium and caesium are in the same group of the periodic table.

Explain, in terms of electrons, why potassium and caesium are in the same group.

Fluorine boils at –188 °C. There are forces between fluorine molecules.

Explain, in terms of these forces, why the boiling point of fluorine is low.

Potassium reacts with fluorine to form potassium fluoride. Potassium fluoride is a solid.

Complete the balanced equation for this reaction and add the state symbols.

.................K (...........) + F₂ (g) → .................KF (...........)

What are the elements in group 1 of the periodic table called?

Figure 14 shows the melting points and boiling points of elements in group 7 of the periodic table.

Figure 14

i) Give, using Figure 14, the boiling point of bromine.

(1)

boiling point of bromine = ..................................... °C

ii) State which two elements from Figure 14 are solids at room temperature.

(1)

Higher Only 

Element Cu has two isotopes. Their mass numbers are 63 and 65. 

• Cu- 63 has a percentage abundance of 69.2%

• Cu- 65 has a percentage abundance of 30.8% 

Estimate the relative atomic mass of element Cu. 

Rutherford’s gold foil experiment led to the development of a different model of the atom.

Describe Rutherford’s model of the atom.

Atoms contain protons, neutrons and electrons. Their masses and charges are compared to each other and are known as relative atomic masses and relative atomic charges.

Complete the table to show the correct relative atomic masses and charges.  

Explain why atoms have a neutral charge. 

In terms of subatomic particles, compare the isotopes of carbon shown in the diagram below.

The atomic model developed by scientists has changed over time as experimental evidence improved understanding.

Explain how Niels Bohr contributed to the atomic model. 

Compare the relative atomic masses and relative atomic charges of the subatomic particles within an atom. 

Higher Tier Only

Figure 1 shows the percentage abundance of two isotopes of chlorine.

Figure 1

Calculate the relative atomic mass of chlorine. 

Explain why carbon-12 and carbon-13 are isotopes of the same element.

Give your answer in terms of subatomic particles. 

Compare J.J. Thomson’s plum pudding model with Rutherford’s nuclear model of the atom. 

Explain what isotopes are. 

Explain how the gold foil experiment led to a better understanding of the nucleus. 

Explain how the characteristics of subatomic particles within an atom contribute to the overall charge and mass of an atom. 

Explain the impact of the discoveries of the electrons, nucleus and neutron on the evolution of the atomic model. 

Higher Tier Only

Explain how the relative atomic mass of an element is calculated and use the example in figure 1 to illustrate your explanation. 

Figure 1

Explain the relationship between mass number and atomic number in determining the identity and properties of an element. Use carbon-12 and carbon-13 as an example. 

Explain the structure of an atom according to the current atomic model. 

Bohr further developed the atomic model proposed by Rutherford.

Compare the main features of Bohr’s improvement to the atomic model.

Rutherford’s model of the atom improved the understanding of the atom. Explain how older models were limited in their understanding of the atom. 

Explain why isotopes of an element will have similar chemical properties.

Explain why an atom does not collapse inwards. 

Explain how Chadwick’s work on the atomic model led to a better understanding of the existence of isotopes. 

The diagram below shows two atoms.

Compare the structures of both atoms. 

Explain why the atoms in part b) react in the same way. 

Compare the mass number and atomic number of the atoms mentioned in question 1b. 

The Bohr model of the atom introduced significant advancements in atomic theory.

Discuss the limitations of the earlier atomic models in explaining the behaviour of electrons within an atom. 

The diagram below shows the chemical symbols of two isotopes of uranium.

Explain why uranium-235 and uranium-238 are categorised as isotopes of the same element. 

Explain the difference in charge between a magnesium atom and magnesium ion. 

Higher Tier Only:

The table in figure 1 shows three isotopes of magnesium with varying abundances.

Explain why the relative atomic mass of magnesium is 24.3 and not a number closer to 24 or 26.

Figure 1

Describe the limitations of Dalton’s atomic model and Thomson’s plum pudding model in describing the structure of the atom.

Explain why the nucleus is described as a concentrated mass at the centre of an atom.

Explain the structure of an atom according to the plum pudding model. 

Explain what the discovery by J.J. Thomson was and what it proved. 

Explain the difference in charge of the nucleus of an atom and an atom as a whole. 

Explain the structure of an atom according to the nuclear model. 

Explain the contributions of different scientists to the understanding of the atomic structure.

Explain the presence of forces within an atom and its impact. 

Higher Tier Only

Explain why the masses and charges of subatomic particles are described as ‘relative atomic masses’ and ‘relative atomic charges’.

Compare the relative sizes of the following things: atom, nucleus and electrons. 

The diagram shows the chemical symbol of magnesium and lithium.

Explain the difference in nucleon number of an atom of magnesium and the nucleon number of an atom of lithium. 

Higher Tier Only

Explain why percentage abundance of isotopes is taken into consideration when calculating the relative atomic mass.