3.3.3 - Group 7 Flashcards Preview

AS/A2 Chemistry - Inorganic > 3.3.3 - Group 7 > Flashcards

Flashcards in 3.3.3 - Group 7 Deck (17):
1

What does fluorine look like?

Pale yellow gas

2

What does chlorine look like?

Green gas

3

What does bromine look like?

Red-brown liquid

4

What does iodine look like?

Black solid

5

The size of the halogens _____ down the group

The size of the halogens increases down the group

6

Mpts/bpts of the halogens _____ down the group. Why?

The mpts/bpts of the halogens increases down the group. More electrons -> stronger vdWs' forces between molecules

7

Bond enthalpies generally ______ down group 7. Exception - why?

Bond enthalpies generally decrease down group 7. Exception - fluorine. Because of fluorine's very small size, non-bonding electrons repel each other from each atom.

8

How do halogens react? E.g. Cl?

They gain one electron each to form -1 ions (become reduced).
E.g. Cl2 + 2e- -> 2Cl-

9

Halogens usually act as ______ agents

Oxidising agents (themselves gain an electron so are reduced)

10

What is the trend in oxidising power down group 7?

Oxidising power decreases down group 7

11

What is the trend in reducing power down group 7?

Reducing power increases down group 7

12

In solution, a halogen will replace a less reactive halide in solution. T/F?

True: in solution, a halogen will replace a less reactive halide in solution. E.g. if the halide ion is below the halogen in the periodic table.

13

Define 'electronegativity'

The power of an atom to attract the shared electrons towards itself in a covalent bond

14

Trend in electronegativity down group 7?

Electronegativity decreases down group 7

15

How do you test for halide ions?

1 - Add dilute HNO3 (aq) to react with any CO3^2- or OH- (that would cause a false positive).
2 - Add AgNO3 (aq)
Ppts form
3 - Add dilute NH3 (aq)
4 - Add conc NH3 (aq)

16

Ppt formed with AgNO3 and speed of formation?
Cl
Br
I

Cl - white - slowest
Br - cream
I - yellow - fastest

17

How do you double check each ppt is really that of the correct ion?

Cl - white ppt - redissolves in dilute NH3 (aq)
Br - cream ppt - redissolves in conc. NH3 (aq)
I - yellow ppt - doesn't redissolves in any. NH3 (aq)