Chem 2/10 test

Electrons are arranged in energy levels around the nucleus of an atom. Explain why the first ionisation energy of calcium is greater than that of potassium.

There are more protons for the same number of energy levels.

This means there is a higher effective nuclear charge, which increases the ionisation energy.

Electron transitions are related to trends in the periodic table. Explain the general increase in the first ionisation energies of the period 3 elements, Na to Ar.

In period 3 all elements have electrons in the n=3 energy level. As you go across the period, number of protons and electrons increases. There is increased attraction so increased nuclear charge, meaning more energy is needed to remove an electron.

Remind yourself of the Rutherford gold foil experiment. Suggest what could be concluded about the experiment given that:

• most alpha particles passing straight through

• very few alpha particles deviating from their path

1. most of an atom consists of empty space

2. there must be a positively charged nucleus, and there must be space between the central positive charge and the outer negative charge.

Which of Cu and Cu²+ will have the higher ionisation energy

Cu²+, because the 3d orbital has been emptied there is a noticeable difference in the effective nuclear charge