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

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

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Question 5
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This question is about chromium and its extraction.

a.

Chromium is a transition metal. Match each property of chromium to the correct reason for that property.

Properties:

  • Conducts heat/electricity
  • High melting point

Reasons:

  • Chromium has delocalised electrons
  • Chromium has layers of atoms which can slide
  • Chromium has strong metallic bonds
  • Chromium has weak intermolecular forces
  • Chromium has a random arrangement of atoms
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b.

Chromium can be mixed with iron and carbon to make stainless steel. What is meant by an 'alloy'?

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c.

Chromite is an ore containing chromium(III) oxide. Chromite ore samples contain between 15% and 35% chromium. Pure chromium(III) oxide always contains 68.4% chromium. How does this show that chromite ore is a mixture and not a compound?

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d.

In one stage of chromium extraction, sodium dichromate, Na2Cr2O7\text{Na}_2\text{Cr}_2\text{O}_7Na2​Cr2​O7​, is used. Give the total number of atoms in the formula unit of Na2Cr2O7\text{Na}_2\text{Cr}_2\text{O}_7Na2​Cr2​O7​.

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e.

A sample of chromite ore contains 28% chromium. Calculate the maximum mass of chromium that can be extracted from 350,000 kg350,000\text{ kg}350,000 kg of this sample of chromite. Give your answer in standard form.

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Markscheme

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

  1. GCSE
  2. /Chemistry
  3. /1.1 A simple model of the atom, symbols, relative atomic mass, electronic charge and isotopes

41 exam-style questions on AQA GCSE Chemistry 1.1 A simple model of the atom, symbols, relative atomic mass, electronic charge and isotopes, covering 1.1.1 Atoms, elements and compounds, 1.1.2 Mixtures, 1.1.3 The development of the model of the atom (common content with physics), 1.1.4 Relative electrical charges of subatomic particles, 1.1.5 Size and mass of atoms, 1.1.6 Relative atomic mass, and 1.1.7 Electronic structure. Each one has a worked solution and a mark scheme showing where the marks go.

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