Atomic Structure (Edexcel GCSE Chemistry)

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. 

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.