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Flashcards in group 2 and 7 Deck (37)
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1

trend in ionisation energy as you go down group 2

decreases

2

why does IE decrease down group 2

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

3

reactivity down group 2

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

4

reactions of group 2 with oxygen

2M + O2>> 2MO

5

reactions of group 2 with chlorine

M + Cl2 >> MCl2

6

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

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-

7

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

solubility increases down the group, increasing the pH

8

test for CO2

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

9

uses of group 2 oxides

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

10

why is magnesium hydroxide safe for consumption?

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

11

equation for lime use in agriculture

Ca(OH)2 + HNO3 >> Ca(NO3)2 + 2H2O

12

solubility of group 2 sulfates

decreases down the group

13

which group 2 sulfates are insoluble

Sr and Ba

14

use of BaSO4

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

15

how to test for sulfate ions

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

16

what happens to nitrates and carbonates upon heating

they decompose

17

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

metal nitrate>> metal oxide + oxygen + nitrogen dioxide
metal nitrate>> metal nitrite + oxygen

18

group 1 nitrates that decompose into nitrogen dioxide

Li ONLY

19

group 2 nitrates that decompose into nitrogen dioxide

ALL OF THEM

20

what colour is nitrogen dioxide

brown

21

factors affecting the decomposition of group 2 nitrates

charge
ionic radius
complexity of nitrates or carbonates

22

how does ionic radius and charge affect stability of group 2

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

23

group 1 metals that decompose

Li ONLY

24

group 2 metals that decompose

ALL OF THEM

25

Mp/bp Trend of group 7
Why?

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

Electronegativity Trend down group 7

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

27

Electronegativity define

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

28

Trend in reactivity down Group 7

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

29

Chlorine Reactions w group 1 and 2

2Na + Cl2 >> 2NaCl
Mg+Cl2 >> MgCl2

30

Displacement reactions of group 7

Takes place in H2O or cyclohexane
More reactive halogen will displace a less reactive one.