group 7 - the halogens

Question 1

what happens as you go down?

Answer 1

• elements have higher boiling point
• elements are darker in colour
• elements are less reactive

Question 2

what ions do they form?

Answer 2

-1

Question 3

chlorine

Answer 3

(Cl2)

poisonous green gas

Question 4

Bromine

Answer 4

(Br2)
poisonus red, brown liquid
gives off orange vapour at room temperature
in water is orange

Question 5

Iodine

Answer 5

(I2)
dark grey crystalline solid
gives off purple vapour when heated
in water is brown

Question 6

why does it get less reactive as atomic number increases?

Answer 6

Halogens only need one electron, so the more electrons there are the more shells there are making it harder to attract electrons because the distance between the electrons and the nucleus are larger meaning the attraction is weaker

Question 7

physical properties

Answer 7

• exists as simple molecules (single covalent bond)

- as you go down molecules become larger, intermolecular forces become stronger (more energy required to break bonds)

Question 8

chemical properties

Answer 8

• react w/ metals to produce salts
• e.g: sodium + chlorine —> sodium chloride
  2Na (s) + Cl2 (g) —> 2NaCl (s)
  react vigorously when heated
• sodium chloride gives orange flame and clouds of white sodium chloride
• halogens become less reactive as you go down

Question 9

when are hallides formed

Answer 9

when they react with hydrogen they produce a hallide compound

e. g (hydrogen chloride)
- hydrogen hallides dossolve in water to produce acidic solutions

Question 10

any halogen ion is

Answer 10

colourless

Question 11

how to test for chlorine

Answer 11

damp blue litmus paper- will bleach turning it white if chlorine is present