C1 Group 7 Elements (page 109)

Question 1

What are the Group 7 Elements known as?

Answer 1

Halogens

Question 2

What are Halogens?

Answer 2

Group 7 elements, and known as Halogens, (Non Metals with coloured vapours)

Question 3

What is Fluorine?

Answer 3

its a very reactive poisonous yellow gas molecule (which is Halogen and Non metal, group 7 element)

Fluorine is critical for the production of nuclear material for nuclear power plants and for the insulation of electric towers. Hydrogen fluoride, a compound of fluorine, is used to etch glass. Fluorine, like Teflon, is used to make plastics and is also important in dental health

Question 4

What is Chlorine?

Answer 4

its a fairly reactive, poisonous dense green gas molecule (halogen and non metal group 7 element)

Chlorine is used as a bleach in the manufacture of paper and cloth, but it is also used to make pesticides (insect killers), rubber and solvents. Chlorine is used in drinking water and swimming pool water to kill harmful bacteria.

Question 5

What is Bromine?

Answer 5

it is dence, poisonous, red-brown volatile liquid molecule (Halogen, non-metal gas, group 7)

It is used in many areas, such as argicultural chemicals, dyestuffs, insecticides, pharmaceuticals and chemical intermediates. Some uses are being phased out for environmental reasons, but new uses continue to be found. Bromine compounds can be used as flame retardants (prevents the outbrake of fire)

Question 6

what is Iodine?

Answer 6

its a dark grey crystaline solid, or a purple vapour molecule, (halogen and Non-Metal, group 7 element)

Its most important role is to ensure proper thyroid function in the human body. It helps to regulate the production of the thyroid hormones thyroxine (T4) and Tridodothyronnie (T3). Getting enough Iodine is essential for preventinglow thyroid hormone production and hypothyroidism

Question 7

As you go down the periodic table in Group 7, what trend happens with the halogens, do they become more or less reactive, any why?

Answer 7

They become less reactive - it is harder to gain an extra electron because the outer shell’s further from the nucleus.

Question 8

Apart from group 7 becoming less reactive as it goes down the periodic talbe, what other trends to group 7 have going down the table?

Answer 8

1 they have Higher melting and boiling points
2 they have higher relative atomic masses

Question 9

Why do all the Group 7 elements react in similar ways?

Answer 9

its because they all have seven electrons in their outer shell

Question 10

Why would Iodine have a higher boiling point than chlorine, in the group 7 elements?

Answer 10

its because Iodine has a higher boiling point than chlorine, as it is further down the group in the periodic table

Question 11

What can Halogens form?

Answer 11

they form Molecular Compounds

Question 12

Can Halogen atoms share electrons? if yes how?

Answer 12

they can share electrons via covalent bonding, with other non-metals, so they can achieve a full outer shell.

eg: HCl, PCl5, HF and CCl4 contain covalent bonds.

Question 13

The compounds that form when halogens react with non-metals all have what molecular structures?

Answer 13

Simple molecular structures

Question 14

Halogens form Ionic Bonds with Metals or Non Metals?

Answer 14

with Metals

Question 15

Halogens form 1-ions called what? when they bond with metals?

Answer 15

Halides (F-, Cl-, Br-, and I-)

when bonded with metals (Na+Cl- or Fe3+Br-3)

Question 16

When compounds form they have what structures?

Answer 16

Ionic structures

Question 17

More reactive Halogens will replace or displace less reactive ones?

Answer 17

Displace

(take over the place, position or role/ forced to take over)

Question 18

Give an example when a displacement reaction occurs between a more reactive halogen and the salt of a less reactive one?

Answer 18

Chlorine can displace Bromine and Iodine from an aqueous solution of its salt (a bromide or iodide).

Question 19

Why would Bromine displace iodine?

Answer 19

because of the trend in reactivity

Cl2(g) + 2KI(aq) &raquo_space;»»> I2(aq) + 2KCI(aq)
(pale green) Brown

Cl2(g) + 2KBr(aq) &raquo_space;»»»> Br2(aq) + 2KCl(aq)
Pale green Orange

Question 20

Group 7 elements that are higher up the table, displace those that are what?

Answer 20

lower down in displacement reactions

(so if you think of displacement reactions like boxing matches, fluorine would be the heavyweight champion, because fluorine is at the top of the group 7 elements

Question 21

Give a balanced symbol equation for for the displacement reaction between bromine and sodium iodide?

Answer 21

Br2 + 2Nal &raquo_space;»»» 2NaBr + l2

Question 22

Why do group 7 elements get less reactive as you go down the group from florine to iodine? (3 marks)

Answer 22

Halogens react by gaining electrons to make a full outer shell (1 mark)

As you go further down the group the outer electrons are further away so there is less attraction between them and the nucleus (1 mark)

This means electrons are harder to gain so they become less reactive (1 mark)