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EDEXCEL Chemistry a level > group 2 and 7 > Flashcards

group 2 and 7 Flashcards

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1
Q

trend in ionisation energy as you go down group 2

A

decreases

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2
Q

why does IE decrease down group 2

A

atomic radius increases
shielding increases, decreasing electrostatic attraction to the outer electron, meaning less energy is required to remove it

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3
Q

reactivity down group 2

A

increases as 1IE and 2IE decreases down the group, meaning that it’s easier to form 2+ ions

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4
Q

reactions of group 2 with oxygen

A

2M + O2» 2MO

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5
Q

reactions of group 2 with chlorine

A

M + Cl2&raquo_space; MCl2

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6
Q

reactions of group 2 with water
how does this affect the pH
support w an ionic equation

A 
increases reactivity down the group.
Be doesn't react at all, Mg will react slowly w cold water while the rest down the group react more vigorously.
M+2H2O >> M(OH)2
this increases the pH
O2-+H2O >> 2OH-
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7
Q

what happens to the solubility of group 2 hydroxides as you go down the group

A

solubility increases down the group, increasing the pH

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8
Q

test for CO2

A

add aqueous calcium hydroxide and a white precipitate should form
Ca(OH)2 (aq) + CO2 (g)&raquo_space; CaCO3 (s) + H2O

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9
Q

uses of group 2 oxides

A 
Mg hydroxide (milk of magnesia) treats indigestion
Ca(OH)2 (lime) raises the pH of soil
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10
Q

why is magnesium hydroxide safe for consumption?

A

although Mg (aq) is toxic to the human body, Mg(OH)2 is insoluble and so non-toxic.

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11
Q

equation for lime use in agriculture

A

Ca(OH)2 + HNO3&raquo_space; Ca(NO3)2 + 2H2O

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12
Q

solubility of group 2 sulfates

A

decreases down the group

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13
Q

which group 2 sulfates are insoluble

A

Sr and Ba

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14
Q

use of BaSO4

A

used as a barium meal in x raying of soft tissue as a contrast fluid.
ordinarily toxic, Ba is insoluble as a sulfate so is safe for consumption

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15
Q

how to test for sulfate ions

A
  1. add dilute HCl or HNO3 (to remove CO32-)
  2. Add Ba(NO3)2 (source of Ba2+)
  3. a white ppt will form
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16
Q

what happens to nitrates and carbonates upon heating

A

they decompose

17
Q

what are the 2 reactions involved in the decomposition of group 2 nitrates

A

metal nitrate» metal oxide + oxygen + nitrogen dioxide

metal nitrate» metal nitrite + oxygen

18
Q

group 1 nitrates that decompose into nitrogen dioxide

A

Li ONLY

19
Q

group 2 nitrates that decompose into nitrogen dioxide

A

ALL OF THEM

20
Q

what colour is nitrogen dioxide

A

brown

21
Q

factors affecting the decomposition of group 2 nitrates

A

charge
ionic radius
complexity of nitrates or carbonates

22
Q

how does ionic radius and charge affect stability of group 2

A

larger, more complex ions of a lower charge are most stable

23
Q

group 1 metals that decompose

A

Li ONLY

24
Q

group 2 metals that decompose

A

ALL OF THEM

25
Q

Mp/bp Trend of group 7

Why?

A

Increases as you go down group 7
As intermolecular forces become stronger due to larger temporary and induced dipoles (due to more electrons) meaning more energy is needed to break them.

26
Q

Electronegativity Trend down group 7

A

Decreases
Atoms get larger down group.
Constant Z eff (=protons- shielding electrons)
F is most electronegative element

27
Q

Electronegativity define

A

The ability of an atom to attract electron density towards itself in a covalent bond.

28
Q

Trend in reactivity down Group 7

A

Decreases
Atomic radius increases, causing electronegativity to decrease
But I- is a better reducing agent than F-

29
Q

Chlorine Reactions w group 1 and 2

A

2Na + Cl2&raquo_space; 2NaCl

Mg+Cl2&raquo_space; MgCl2

30
Q

Displacement reactions of group 7

A

Takes place in H2O or cyclohexane

More reactive halogen will displace a less reactive one.

31
Q

How do you see a more distinct colour change in displacement reactions of group 7

A

Add cyclohexane to see a greater change

32
Q

Colours of group 7 in cyclohexane

Without cyclohexane.

A

Cl2 > yellow> colourless prior
Br2 > brown > yellow prior
I2 > purple > yellow prior

33
Q

Disproportionate on define

A

The Oxidation and reduction of the same element in an equation

34
Q

Uses of chlorides

A

Weed killer
Bleach
Disinfectant

35
Q

Trend in oxidising power as you go down group 7

A

Decreases

36
Q

Trend in reducing power as you go down group 7

A

Increases

37
Q

3 forms sulfuric acid can be oxidised to

A

Sulfur dioxide SO2 (4+)
Sulfur (0)
Sulfur hydride (-2)

EDEXCEL Chemistry a level (12 decks)

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