Groups 1, 2 & 7 Flashcards Preview

Chemistry A level Edexcel > Groups 1, 2 & 7 > Flashcards

Flashcards in Groups 1, 2 & 7 Deck (32)
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1
Q

What are the trends in 1st ionisation energy as you go down groups 1 + 2?

A

As you go down group 1 +2, ionisation energy decreases as the distance between the nucleus + valence electrons increases, so outer electrons are easier to remove.

The nuclear charge also increases, however the shielding from other shells outweighs this.

2
Q

Describe reactivity trends down groups 1 + 2

A

Reactivity down the groups increase as they react by losing electrons

3
Q

Explain HISDOG

A
Hydroxides
   Increase
  Sulphates
  Decrease
dOwn
  Group

Trends in solubility down group 2

4
Q

Explain the trend in thermal decomposition down groups 1 + 2

A

Thermal decomposition gets harder down the groups, as the cations get larger and are less polarising, so there is less weakening of bonds within the anion

5
Q

Show what happens with Li and group 2 nitrates

A

2LiNO3(s) —> Li2O(s) + 2NO2(g) + 1/2 O2(g)

NO2 = brown fumes

(Group 2 reacts in same way)

6
Q

Show what happens with the rest of group 1 nitrates

A

NaNO3(s) —> NaNO2(s) + 1/2 O2(g)

No brown fumes

7
Q

Show what happens with Li and group 2 carbonates

A

LiCO3(s) —> Li2O(s) + CO2(g)

CO2 turns limewater milky

(Group 2 reacts in same way)

8
Q

Explain what happens to rest of group 1 carbonates

A

Do not undergo thermal decomposition as cations are too large and too lowly charged, so cannot polarise anion enough to break bonds

9
Q

Describe a flame test

A

Clean nichrome wire by dipping in HCl

Put wire in flame

Dip wire in metal sample

Put in blue flame and observe colour

10
Q

What colour does Li show?

A

Red

11
Q

What colour does Na show?

A

Yellow/orange

12
Q

What colour does K show?

A

Lilac

13
Q

What colour does Rb show?

A

Red/purple

14
Q

What colour does Cs show?

A

Blue/violet

15
Q

What colours do Be and Mg show?

A

No visible colours emitted (out of visible light spectrum)

16
Q

What colour does Ca show?

A

Brick red

17
Q

What colour does Sr show?

A

Crimson red

18
Q

What colour does Ba show?

A

Apple green

19
Q

How do we observe the colours in flame tests?

A

Electrons absorb energy and are excited from ground state energy level to higher (excited) state.

When they fall back down again energy of a specific frequency is released which we observe as colour

20
Q

Describe trend in melting point of group 7

A

Melting point increases down the group because there are more electrons, so are more/stronger London forces between the molecules, therefore more energy is required to break them and change physical state

21
Q

Explain trend in electronegativity down group 7

A

Decreases down group as:

Nuclear charge increases but shielding also increases and outweighs nuclear charge. Atomic radius also increases so nuclear attraction on bonded electrons decreases

22
Q

Explain trend in reactivity down group 7

A

Decreases down group as:

Nuclear charge increases but shielding also increases and outweighs nuclear charge. Atomic radius also increases so nuclear attraction on incoming electrons decreases

23
Q

State the colours of chlorine as an element, in aqueous and organic solutions

A

Element: green gas

Aqueous: pale green

Organic: pale green

24
Q

State the colours of bromine as an element and in aqueous and organic solutions

A

Element: red/brown liquid

Aqueous: orange

Organic: orange

25
Q

State the colours of iodine as an element and in aqueous and organic solutions

A

Element: grey solid

Aqueous: brown

Organic: purple

26
Q

What does disproportionation mean?

A

Element in single species is both oxidised and reduced in a reaction

27
Q

What is observed when you react Cl- with H2SO4?

A

Misty fumes

28
Q

What is observed when you react Br- with H2SO4?

A

Misty fumes, brown fumes and colourless gas with choking smell

29
Q

What is observed when you react I- with H2SO4?

A

Misty fumes, purple fumes/black solid, colourless gas with chocking smell, yellow solid and colourless gas with rotten egg smell

30
Q

What is seen when you add Cl- to AgNO3?

A

White precipitate - dissolves in dilute ammonia

31
Q

What is seen when you add Br- to AgNO3?

A

Cream precipitate - dissolves in concentrated ammonia

32
Q

What is seen when you react I- with AgNO3?

A

Yellow precipitate - doesn’t dissolve in ammonia