Periodicity

Question 1

Defintion of periods

Answer 1

The horizontal rows of elements that show trends (gradual changes) in physical and chemical properties across the period. These trends are repeated across each period.

Question 2

Defintion of periodicity

Answer 2

The repeating pattern of trends across different periods.

Question 3

Defintion of groups

Answer 3

Vertical columns of elements that have similar physical and chemical properties. Atoms down each group have the same number of outer electrons (indicated by the group numbers).

Question 4

Definition of first ionisation energies

Answer 4

The energy required to remove 1 mole of electrons to 1 mole of gaseous atoms.

Question 5

The main factors that affect first ionisation energy trends

Answer 5

1. Number of electron shells.
2. Number of electrons in outer shell.
3. Number of protons.
4. Where are the electrons? - On the same shell, more shells = more shielding.
5. Nuclear attraction- stronger? weaker?

Question 6

How atomic radii changes across a period…

Answer 6

1. Atomic radii decreases.
2. Outermost electrons in the same shell.
3. Number of protons (nuclear charge) increases.
4. Nuclear attraction on outermost electrons increase (electrons are pulled closer to the nucleus).

Question 7

How atomic radii changes down a group…

Answer 7

1. Atomic radii increases.
2. More shells.
3. Greater distance of outermost electron to nucelus.
4. More shielding on outermost electrons from inner electrons.
5. Nuclear attraction on outermost electrons decreases (electrons are not pulled as close to nucleus).
6. Although number of protons (nuclear charge) increases this is ‘far outweighed’ by more distance and shielding.

Question 8

Definition of successive ionisation energies

Answer 8

The energy required to remove each electron in turn. This is the process of removing electrons from the same atom starting from the outer electron and working in.