Unit 6

Question 1

Period number of an element

Answer 1

The number of occupied electron shells in an atom of the element

Question 2

Group number of an element

Answer 2

Indicates the number of outermost shell electrons in an atom of an element

Question 3

Why does elements in the same group have similar chemical properties?

Answer 3

Because they have the same number of outermost shell electrons in their atoms.

Question 4

Group I metals - alkali metals (page 1)

Answer 4

Each atom in this group only has one outermost shell electron

Characteristics:
- good conductor of electricity
- softer than most other metals
- densities of lithium, sodium and potassium are all less than 1g cm-3, so they float on water.

General:
- relatively low densities, melting points, boiling points when compared with most other metals
- melting point of group I elements decrease going down the group.

Question 5

Group I metals - alkali metals (page 2)

Answer 5

Typical chemical reactions:
- react with oxygen to form oxides
- react with chlorine to form chlorides