Periodicity

Question 1

How does the periodic table arrange elements?

Answer 1

By proton number.

Question 2

What happens to atomic radius across the period and explain why.

Answer 2

Atomic radius decreases down a period because:
More protons, more positive charge in nucleus. Electrons are pulled closer to the nucleus, making the atomic radius smaller.
Extra electrons that the elements getting across a period added to the outer energy level so don’t provide any extra shielding.

Question 3

What happens to ionisation energy across a period and state why.

Answer 3

Ionisation energy increases across the period because of the increasing attraction between the outer shell electrons and the nucleus, due to the number of protons increasing.
However this depends on the period.

Question 4

Give the shape, structure and bonds in silicon. Does it have a high or low melting point?

Answer 4

Macromolecular
Tetrahedral structure
Strong covalent bonds
A lot of energy needed to break these bonds, so silicon has a high melting point

Question 5

What is melting point linked to?

Answer 5

Bond strength and structure.