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2.5 Types of substance

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Question 5
F

A student uses two models in a revision lesson on covalent bonding:

• a dot-and-cross diagram of a water molecule

• a ball-and-stick model of a methane molecule, made from plastic balls and sticks

a.

State what the sticks represent in the ball-and-stick model of methane.

[1]
b.

Each ball in the student's model is 3 cm wide. A real carbon atom is about 1.5 × 10-10 m wide. Calculate how many times wider the ball is than a real carbon atom. 1 cm = 1 × 10-2 m

[2]
c.

Describe what each of the two models shows about the bonding and structure of the molecule, and describe the limitations of each model.

[6]
Markscheme

2.5 Types of substance Questions

  1. GCSE
  2. /Chemistry
  3. /2.5 Types of substance

48 exam-style questions on Edexcel GCSE Chemistry 2.5 Types of substance, covering 2.5.1 Classifying substances by structure and bonding, 2.5.2 Properties of ionic and simple molecular substances, 2.5.3 Giant covalent structures: diamond and graphite, 2.5.4 Fullerenes, graphene and simple polymers, 2.5.5 Properties of metals and non-metals, and 2.5.6 Limitations of bonding models and representations. Each one has a worked solution and a mark scheme showing where the marks go.

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