Group 1 and 2

Question 1

What can all group 2 metals form

Answer 1

ionic compounds in which they donate these two outermost electrons

Question 2

are group 2 metals reducing agents or oxidising agents

Answer 2

act as reducing agents) to become an ion with +2 charge (so they themselves become oxidised)

Question 3

What is first ionisation energy

Answer 3

energy needed to remove the first outer electron of an atom

Question 4

how is the increased nuclear charge down the group outweighed

Answer 4

increased shielding effect and a larger distance between the outermost electrons and nucleus outweigh the attraction of the higher nuclear charge

Question 5

when reacting group 2 metal with water and oxygen what is the general equation

Answer 5

2M (s) + O2 (g) → 2MO (s)

M (s) + 2H2O (l) → M(OH)2 (s) + H2 (g)

Question 6

what are the exceptions when reacting group 2 metal with water and oxygen

Answer 6

Sr and Ba also form a peroxide, MO2

Be which does not react with water

Question 7

why is the reaction of magnesium with cold water form a weak alkaline

Answer 7

magnesium hydroxide is only slightly soluble

Question 8

what happens when magnesium is heated in steam

Answer 8

it reacts vigorously with steam to make
Mg (s) + H2O (g) → MgO (s) + H2 (g)

Question 9

all group 2 oxides are basic except which one

Answer 9

BeO which is amphoteric (it can act both as an acid and base)

Question 10

what happens when group 2 metal oxide reacts with water

Answer 10

oxide + water → hydroxide2

Group 2 oxides react water to form alkaline solutions which get more alkaline going down the group

Question 11

what happens when group 2 oxide with hcl / sulfuric acid

Answer 11

Group 2 sulfates or chlorides with water

insoluble sulfates form at the surface of the oxide, which means that the solid oxide beneath it can’t react with the acid

Question 12

what do group 2 metal hydroxides form when react with dilute acid

Answer 12

colourless solutions of metal salts

The sulfates decrease in solubility going down the group

group 2 hydroxide + dilute hydrochloric acid → magnesium chloride + water

Question 13

Explain the solubility if group 2 hydroxides

Answer 13

Going down the group, the solutions formed from the reaction of Group 2 oxides with water become more alkaline

The higher the concentration of OH- ions formed, the more alkaline the solution
The alkalinity of the formed solution can therefore be explained by the solubility

Question 14

how do oxides and hydroxides dissolve in water show ionic equations

Answer 14

O2- (aq) + H2O(l) → 2OH- (aq)

X(OH)2 (aq) → X(aq) + 2OH- (aq)

Question 15

what happens when group 2 carbonate gets decomposed

Answer 15

they are heated to form the metal oxide and give off carbon dioxide gas

Going down the group, more heat is needed to break down the carbonates

Question 16

which group 1 nitrate gets thermally decomposed and what happens to rest of group 1 nitrates

Answer 16

4LiNO3 (s) –> 2Li2O (s) + 4NO2 (g) + O2 (g)

2XNO3 (s) —> 2XNO2 (s) + O2 (g)

Question 17

why does the thermal stability of group 1 and group 2 increase down group

Answer 17

more heat is needed to break down the carbonate and nitrate ions

The smaller positive ions at the top of the groups will polarise the anions more than the larger ions at the bottom of the group

The small positive ion attracts the delocalised electrons in the carbonate ion towards itself
The higher the charge and the smaller the ion the higher the polarising power

The more polarised they are, the more likely they are to thermally decompose as the bonds in the carbonate and nitrate ions become weaker

Question 18

how can you carry out a flame test

Answer 18

any mention of platinum / nichrome wire /
loop
(1)
dip the wire into (clean / fresh concentrated) hydrochloric acid / HCI
(1)
dip the (wet) wire into the solid and place in a (non-luminous
/ roaring / blue Bunsen) flame

Question 19

why does the flame colour occur

Answer 19

heat causes the electron to move to a higher energy level
The electron is unstable at this energy level so falls back down
As it drops back down from the higher to a lower energy level, energy is emitted in the form of visible light energy with the wavelength of the observed light

Question 20

why does mg2+ not have a colour

Answer 20

The energy emitted during a flame test involving magnesium is outside the visible spectrum

no emission of light

Question 21

why add a small amount of sulphuric acid in carbonate ion test

Answer 21

The acid reacts with the carbonate ions to form carbon dioxide and water, and so gets rid of them before you add the barium chloride.

Question 22

does magnesium carbonate have higher thermal stability than barium and why

Answer 22

(Magnesium carbonate is less thermally stable because) Mg2+ is smaller has a greater charge density

Polarising power
*so more likely to polarise / distort (the carbonate (ion) / anion)

Bonds
* and so weaken the C-O bond or the bond(s) within the carbonate ion

Question 23

reaction of carbonate with acid

Answer 23

salt + water + carbon dioxide

Question 24

two reasons why wire is made of nichrome and not iron

Answer 24

iron produces a colour nichrome produces no colour (when heated in the flame test)
iron can produce a colour/sparks
(1)
nichrome is inert/ stable to heat/unreactive or
iron reacts with oxygen/air and or hydrochloric acid

Question 25

why is acid dipped into wire and heated

Answer 25

to clean the wire and remove any residue/ impurities

Question 26

two observations when magnesium nitrate is heated

Answer 26

brown fumes of no2 gas
white powdered solid forms

Question 27

explain trend in thermal stability in group 2 nitrates

Answer 27

Nitrates increase in stability down Group 2 as ionic
radius increases (as you go down group)
* so polarising ability of metal (ion) decreases / distorts (the electron cloud of) the anion less

*weakening of N-O bonds (in nitrate ion) is less

Question 28

two gases given off in thermal decomposition of group 2 nitrate and appearances

Answer 28

oxygen - relights
nitrogen dioxide - brown fumes
X(NO3)2 –> XO + 1/2O2 + 2NO2

Question 29

what does the thermal decomposition of a G2 carbonate form

Answer 29

metal oxide and carbon dioxide

Question 30

flame colour for Li+

Answer 30

red

Question 31

flame colour for Na+

Answer 31

yellow

Question 32

flame colour for K+

Answer 32

lilac

Question 33

flame colour for Rb+

Answer 33

red

Question 34

flame colour for Cs+

Answer 34

blue

Question 35

flame colour for Mg2+

Answer 35

Nothing

Question 36

flame colour for Ca2+

Answer 36

brick red

Question 37

flame colour for Sr2+

Answer 37

red

Question 38

flame colour for Ba2+

Answer 38

green

Question 39

explain how reactivity of group 2 elements is determined by electronic configuration

Answer 39

the outerfurther from the nucleus

there is more shielding (from shells of inner electrons) or
there is an increase in repulsion between the filled inner shells and the electron removed

so the (first) ionisation energy decreases (down the group) and
so the reactivity increases

Question 40

why experimental may differ from calculated

Answer 40

incomplete reaction

Question 41

test for sulfate ions

Answer 41

add a few drops of dilute hydrochloric to the sample.
add a few drops of dilute barium chloride or barium nitrate solution.
a white precipitate

Question 42

give a reason why a flame test on mixture of potassium chloride and strontium chloride

Answer 42

red will mask lighter colour

Question 43

give reason why the wire is dipped into acid and heated in first stage

Answer 43

remove residue / clean wire

Question 44

why is fresh concentrated HCL used in second stage

Answer 44

HCL contaminated with residue from previous test

Question 45

test for ammonia

Answer 45

adding sodium hydroxide solution and warming gently. If the compound contains ammonium ions, you will get ammonia gas produced which you can test with damp red litmus paper which it turns blue

Question 46

Thermal decomposition of group 2 carbonates and lithium carbonate (rest of group 1 carbonates don’t decompose)

Answer 46

XCO3 (s) —> XO (s) + CO2 (g)