S Block

Question 1

Group 1 and 2 elements are know as s-block elements, why?

Answer 1

They all have outer electrons in the s subshell; ns^1 and ns^2

Question 2

Group 1 metals like to ___ one outer electron
Group 2 metals like to ___ one outer electrons

Answer 2

Lose

Lose

Question 3

Therefore m, groups 1 and 2 are what agents?
Since they become what when undertaking chemical reactions?

Answer 3

Powerful reducing agents

Oxidised

Question 4

Group 1 and 2 metals easily behave this way, why?

Answer 4

Since their ionisation energies are low

Question 5

What are the equations to show how group 1 and 2 metals are ionised?

Answer 5

Group 1:

M ————> M^+ + e^-

Group 2:

M^2+ ——-> M^2+ + 2e^-

Question 6

Reaction groups 1 and 2 elements

What should you remember?

Answer 6

Remember that all reactions of groups 1 and 2 will demonstrate oxidation since they like to lose their outer electrons.

Question 7

Reactions with oxygen:

Group 1

Answer 7

All very reactive metals
Have to be stored out of contact with air to prevent oxidation

Reactivity increases as you go down the group

Question 8

Reactions with oxygen:

Group 1
Continued

What are the elements stored in?

Answer 8

Lithium, sodium and potassium are stored in oil. (Lithium in fact floats on the oil, but there will be enough oil coating it to give it some protection. It is, anyway, less reactive than the rest of the Group.)

Rubidium and caesium are normally stored in sealed glass tubes to prevent air getting at them. They are stored either in a vacuum or in an inert atmosphere of, say, argon.
The tubes are broken open when the metal is used.

Question 9

Reactions with oxygen:

Group 2

Explain
Examples (Magnesium and calcium)
Summary

Answer 9

All the metals in group 2 react with oxygen, but with increasing ease down the group. They all form white oxides when heated in oxygen

Magnesium + oxygen
2Mg + O2 —> 2MgO

Calcium + oxygen
2Ca +2O —> 2CaO

Summary:
A metal + oxygen gives a metal oxide

Question 10

Flame tests

Compounds containing the ion:
Lithium
Sodium
Potassium
Magnesium
Calcium
Strontium
Barium

Answer 10

Lithium - deep red
Sodium - yellow/orange
Potassium - lilac
Magnesium - colourless
Calcium - brick red
Strontium - crimson
Barium - apple green

Question 11

Flame tests:

What can the colour test be used for?

Answer 11

To identify the element present as the colours are those of the compounds of group 1&2

Question 12

Reactions with water:

Group 1
General observations

Answer 12

• All group 1 metals react vigorously or even explosively with cold water to produce colorless solutions. (All group 1 hydroxides are soluble)
• In each case, a solution of the metal hydroxide is produced together with hydrogen gas, which we see as fizzing and bubbling.
  (What you observed because of hydrogen)

• Group 1 metals become more reactive towards water as we go down the Group.

Question 13

Reactions with water:

Group 1
Equations
Sodium and potassium

Answer 13

Sodium and water
2Na + 2H2O —> 2NaOH + H2

Question 14

Reactions with water:

Group 1
Metals and observations in water

Lithium
Sodium
Potassium

Answer 14

Lithium:
Fizzes and bubbles, moves around on surface of water

Sodium:
As above but also bursts into flame

Potassium: also bursts into flame with a much more explosive/violent reaction

Question 15

Reactions with water:

Group
Briefly describe

Answer 15

Group 2 elements react less readily with water than group 1 elements.
However they react with increasing vigour on the descent of the group

Question 16

Reactions with water:

Group 2
Metals and observations in water

Magnesium
Calcium
Strontium/barium

Answer 16

Magnesium:
Reacts vigorously only with steam

Question 17

Reactions with water:

Group 2
Metals and observations in water

Calcium
It ___ in ___ water.
Reaction is ____.
Water turns ____ due to ____ of ____.

Answer 17

Calcium: calcium sinks in cold water. Reaction is vigorous. Water turns milky due to the low solubility of calcium hydroxide

Question 18

Reactions with water:

Group 2
Metals and observations in water

Strontium/ barium:
Reacts more ___ than___. ___ in water. ___ solutions are produced since their hydroxides are ____ ___.

Answer 18

Strontium/ barium:
Reacts more vigorously than magnesium/ calcium. Sink in water. Colourless solutions are produced since their hydroxides are more soluble

Question 19

Reactions with water:

Group 2
Metals and observations in water

Magnesium + water

Answer 19

Mg + 2H2O —> Mg(OH)2

Question 20

Reactions with water:
Summary

Answer 20

If you add a group 2 metal and water you get metal hydroxide and hydrogen gas

Question 21

Reactions with dilute acid:
Only require group 2

The elements _____ all react with _____ vigour with acids such as ___ and ____ on decent of the group

Answer 21

The elements Mg-Ba all react with increasing vigour with acids such as HCI and H2O4 on decent of the group

Question 22

Reactions with dilute acid:

What are redox reactions?

Answer 22

The metal is oxidised form oxidation state zero to oxidation state (+2) whilst a corresponding reduction occurs.

Question 23

Reactions with dilute acid:

Two examples of redox reactions
Magnesium and calcium

Answer 23

Magnesium + sulphuric acid
Mg + H2SO4 —> MgSO4 + H2
Slight PPT

Calcium + hydrochloric acid
Ca + 2HCl —> CaCl2 + H2

H must exist like H2

Question 24

Reactions of Group 2 with OH^- SO4^2- CO3^2- ions (solubility trends):

With OH- ions

Write a balanced equation for

MgCl2(aq) + NaOH(aq) —>

Answer 24

MgCl2(aq) + 2NaOH(aq) —> Mg(OH)2 + 2NaCl

Question 25

Reactions of Group 2 with OH^- SO4^2- CO3^2- ions (solubility trends):

With OH- ions

Precipitates (PTT) of:

Mg(OH)2
Ca(OH)2
Ba(OH)2

Answer 25

Mg(OH)2. White ppt
Ca(OH)2. V light ppt
Ba(OH)2. No ppt

Question 26

Reactions of Group 2 with OH^- SO4^2- CO3^2- ions (solubility trends):

With OH- ions

Ionic equation;
from your equations, what can you deduce about the trend in solubility of the hydroxides in group 2

Answer 26

Solubility of group 2 hydroxides increases down the group

Remember that when we react group 2 metals with water we form metal hydroxides, this trend explains why the reaction between calcium and water produces a milky solution whilst the reaction between barium and water produces a colourless solution.

Question 27

Reactions of Group 2 with OH^- SO4^2- CO3^2- ions (solubility trends):

With SO4^2- ions

Equation of MgCl2(aq)