Group 2 Elements

Question 1

What is an s-block element?

Answer 1

Element which has atom with highest energy / outer electron in s-subshell.

Question 2

What does basic mean?

Answer 2

Proton acceptor.

Question 3

What are the characteristics of the Group 2 elements?

Answer 3

Metals with low densities.
Silver-grey colour when clean but tarnish easily.
Regarded as s-block elements.

Question 4

What happens to the atomic radius of the Group 2 metals going down the group?

Answer 4

Increases

Question 5

What is the radius of an atom determined by?

Answer 5

Number of layers of electrons around nucleus.
Pull outermost electrons feel from nucleus.

Question 6

What is the explanation for the increase in atomic radius going down Group 2?

Answer 6

Metals get bigger down group as number of filled shells in atom increases.

Question 7

Why do the outer electrons in a Group 2 metal experience a greater nuclear charge than in Group 1 metals?

Answer 7

Atomic radius of Group 2 metal is smaller.

Question 8

What is the ionisation energy of the Group 2 elements determined by?

Answer 8

Charge of nucleus.
Amount of shielding by inner electrons.
Distance between outer electrons and nucleus.

Question 9

What happens to the ionisation energy of the Group 2 metals going down the group?

Answer 9

Decreases

Question 10

What is the explanation for why the ionisation energy of the Group 2 elements decrease going down the group?

Answer 10

Shielding decrease, making outermost electrons easier to remove.

Nuclear pull increases but effective nuclear pull decreases.

Question 11

What happens to the melting point of the Group 2 metals going down the group?

Answer 11

General decrease

Question 12

Why does the melting point of the Group 2 elements decrease going down the group?

Answer 12

Decrease in attraction between delocalised electrons and positive metal ions as ions get bigger.

Question 13

Why is the melting point of of Group 2 metals much higher than in Group 1 metals?

Answer 13

Metallic bond is as result of sharing 2 electrons per atom.

Question 14

Which Group 2 element has an anomalously low melting point?

Answer 14

Mg due to different metallic structure.

Question 15

What is the word equation for the reaction of Group 2 metals with water?

Answer 15

Metal + Water > Metal hydroxide + Hydrogen

Question 16

What is the word equation for the reaction of Group 2 metals with steam?

Answer 16

Metal + Steam > Metal oxide + hydrogen

Question 17

What colour is the metal hydroxide produced in the reaction of Group 2 metals with water?

Answer 17

White

Question 18

What is formed in the reaction of Group 2m metals with oxygen?

Answer 18

Solid white oxide (basic).

Question 19

What is observed in the reaction of each of the Group 2 metals with oxygen?

Answer 19

Mg - bright white light
Ca - brick red flame
Ba - apple green flame

Question 20

What is the equation for the reaction of the Group 2 metals with acid?

Answer 20

Metal + Acid > Metal salt + Hydrogen

Question 21

What colour salt is produced from the reaction of the Group 2 metals with acid?

Answer 21

White

Question 22

How does the reactivity of the Group 2 metals reacting with acid change going down the group?

Answer 22

Increases.

Question 23

How vigorous are the reactions of the Group 2 metals with acid compared to with water?

Answer 23

More vigorous with acid.

Question 24

What is the equation for the reaction of the Group 2 metal oxides with water?

Answer 24

Metal oxide + Water > Metal hydroxide

Question 25

Why does the reactivity of the Group 2 metal oxides with water increase going down the group?

Answer 25

Ionisation energy decreases. Lower activation energy needed for reaction. Faster rate of reaction occurs.

Question 26

What are the uses of calcium?

Answer 26

Production of limewater. Cement and concrete.

Question 27

What are the equations for the production of limewater from limestone?

Answer 27

Calcium carbonate > Calcium oxide + Calcium Dioxide Calcium oxide + Water > Calcium hydroxide

Question 28

What apparatus is used for the thermal decomposition of calcium carbonate (limestone)?

Answer 28

Lime kiln.

Question 29

What is cement made up of?

Answer 29

Mixture of calcium oxide and silica (sand and aluminium oxide).

Question 30

What are the 2 equations for the formation of cement?

Answer 30

CaO + SiO2 > CaSiO3 CaO + Al2O3 > Ca(AlO2)2

Question 31

What is concrete made from?

Answer 31

Cement with gravel and more sand added.

Question 32

What is thermal stability?

Answer 32

How stable it is to heat compound and whether will decompose on heating.

Question 33

What is the trend in the thermal stability of the Group 2 carbonates going down the group?

Answer 33

Increases

Question 34

What is the general equation for the thermal decomposition of the Group 2 carbonates?

Answer 34

MCO3 > MO + CO2

Question 35

Why does the thermal stability of the Group 2 carbonates increase going down the group?

Answer 35

Size of metal cation increases. Charger density of cation decreases. Cation less able to polarise and destabilise carbonate ion so needs more energy.

Question 36

What is the trend in the thermal stability of the Group 2 hydroxides going down the group?

Answer 36

Increases

Question 37

What is the general equation for the thermal decomposition of the Group 2 hydroxides?

Answer 37

M(OH)2 > MO + H2O

Question 38

Why does the thermal stability of the Group 2 hydroxides increase going down the group?

Answer 38

Large cation has lower charge density, so less able to polarise and destabilise hydroxide ion. More energy needed to complete decomposition.