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ScotlandChemistry

Area 1: Chemical Changes and Structure

5 dot points across 5 inquiry questions. Click any dot point for a focused answer with worked past exam questions where available.

What controls how fast a chemical reaction takes place?

Reaction rate and how it is followed, collision theory, the effect of concentration, particle size, temperature and catalysts on rate, the activation energy, the activated complex and the potential energy diagram.
An SQA Higher Chemistry answer on controlling the rate of reaction, covering how rate is measured, collision theory, the effects of concentration, particle size, temperature and catalysts, the activation energy and the activated complex on a potential energy diagram, with worked rate calculations.
11 min answer →

What happens to electrons when substances are oxidised and reduced?

Oxidation and reduction defined in terms of electron loss and gain, the meaning of oxidising and reducing agents, writing ion-electron half-equations, combining them into redox equations, and the electrochemical series.
An SQA Higher Chemistry answer on oxidising and reducing agents, covering oxidation and reduction as electron loss and gain, writing and balancing ion-electron half-equations, combining them into redox equations, and using the electrochemical series to predict the direction of electron flow.
11 min answer →

Why do the properties of the elements change in regular patterns across the periodic table?

The trends in covalent radius, first ionisation energy and electronegativity across periods and down groups, explained in terms of nuclear charge, number of occupied shells and the screening effect of inner electrons.
An SQA Higher Chemistry answer on periodic trends, explaining how covalent radius, first ionisation energy and electronegativity change across periods and down groups in terms of nuclear charge, the number of occupied electron shells and the screening effect of inner electrons.
10 min answer →

How does the position of an element in the periodic table explain its properties?

The arrangement of elements in the periodic table by atomic number into groups and periods, the link between electron arrangement and chemical behaviour, and the meaning of covalent radius, ionisation energy and electronegativity.
An SQA Higher Chemistry answer on periodicity, covering how elements are arranged by atomic number into groups and periods, how electron arrangement explains chemical behaviour, and the three trends of covalent radius, ionisation energy and electronegativity.
10 min answer →

How do the bonds and forces between particles explain the properties of a substance?

The types of bonding and structure (covalent molecular, covalent network, ionic, metallic), the intermolecular forces including London dispersion forces, permanent dipole-permanent dipole interactions and hydrogen bonding, and how these explain physical properties.
An SQA Higher Chemistry answer on structure and bonding, covering covalent molecular, covalent network, ionic and metallic structures, the intermolecular forces of London dispersion, permanent dipole interactions and hydrogen bonding, and how these explain melting points, boiling points and solubility.
11 min answer →