Chapter 4 - periodicity

Question 0

Define the term period

Answer 0

A horizontal row in the periodic table, they have trends in their properties

Question 1

Define the term group

Answer 1

Vertical column of elements, similar chemical properties as they have the same outer shell electron arrangement

Question 2

Describe and explain the trends in melting and boiling points of sodium to aluminium

Answer 2

Increases, the strength of the metallic bond increases as there’s more electrons in the mobile sea, the ions have a higher charge, the inter ionic distances are closer

Question 3

Explain why the melting point of silicon is so high

Answer 3

Silicon is a giant macromolecule and each Si atom has 4 strong covalent bonds which require a lot of energy to overcome

Question 4

Describe and explain the trend of atomic radius across period 3

Answer 4

Decreases as there are progressively more protons pulling on electrons in the same shell so the attraction is greater

Question 5

Describe and explain the trend in first ionisation energy across a period

Answer 5

Increases, there are progressively more protons pulling on the same shell of outer electrons so the attraction is greater and the atomic radius is smaller so more energy is required to ionise the atom

Question 6

Describe and explain the trend in first ionisation energy across a group

Answer 6

Decreases, there are more inner electron shells shielding the outer electrons from the +ve nuclear charge; the outer electron shells are further away so are held in more weakly, so the first ionisation energy decreases

Question 7

Describe and explain the trend in atomic size across a group

Answer 7

Increases, theres another electron shell