Atomic And Physical Properties Period 3

C h e m g u i d e – q u e s t i o n s

PERIOD 3: ATOMIC AND PHYSICAL PROPERTIES

1. Write the full electronic structures for a) silicon, b) sulphur. You can condense p electrons in inner

orbitals as 2p

, but should show the details for the outer orbitals.

2. The first ionisation energies of the Period 3 elements are shown in the bar chart below.

a) Define first ionisation energy.

b) The general trend across the period is for first ionisation energy to increase. Explain why that is.

c) There is a break in this trend between magnesium and aluminium. Explain why the first

ionisation energy of aluminium is less than that of magnesium.

d) There is also a break in the trend between phosphorus and sulphur. Explain why the first

ionisation energy of sulphur is less than that of phosphorus.

3. Excepting argon, the atomic radii of the Period 3 elements fall as you go across the period.

a) Why is it necessary to except argon?

b) Explain why the atomic radii fall across the period.

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