PERIODICITY/ GROUP 2 METALS

Question 1

How are elements arranged in their periodic table?

Answer 1

elements are arranged according to their proton number

Question 2

What does the group number indicate on the periodic table?

Answer 2

number of outer e- of an element

Question 3

what are the 4 block of the periodic table

Answer 3

s
p
d
f

Question 4

What is periodicity?

Answer 4

trends within periodic table

Question 5

why does the radius decrease along period 3?

Answer 5

increase in charge
same number of shells so same shielding
outer e- attracted more strongly

Question 6

state the general trend in the 1st ionisation energies of the period 3 elements sodium to Cl

Answer 6

increases

Question 7

identify the element in P2 that has the highest 1st ionisation energy

Answer 7

Neon

Question 8

Trend in atomic radius down a group?

Answer 8

atomic radius increases

Question 9

why does atomic radius increases down a group?

Answer 9

more shells so increase shielding
greater distance between outer e- and nucleus so less attraction between nucleus and outer e-
atomic radius increases

Question 10

trend in ionisation energy along a period?

Answer 10

ionisation energy increases

Question 11

why does ionisation energy increases along a period?

Answer 11

atomic radius decreases
increases in charge
outer e- is strongly attracted to nucleus so requires so more energy required to remove outer e-

Question 12

trend in ionisation energy down a period?

Answer 12

ionisation energy decreases

Question 13

why does ionisation energy increases down a period?

Answer 13

attraction between nucleus and outer e- decreases
more shielding
less energy required to remove outer e-

Question 14

what happens to melting point across P3? (6- marker)

Answer 14

STAGE 1
1.Na , Mg , Al have metallic bonding
2.higher density charge along Na=+1 , Mg=2+ , Al= 3+
increase in electrostatic forces of attraction from Na to Al so more energy needed to break them
STAGE 2
1.silicon has the highest melting point
2. Macromolecular structure , very similar to diamond held together by strong covalent bonds between atoms
3. requires a lot of energy to break
STAGE 3
1- P, S and Cl exsist as simple molecular.
2. P–> P4 S–> S8 Cl–> Cl2
3. S8 rings are the biggest of the 3 molecules so have the strongest induced dipole dipole
4. Cl2 atomic molecule are the smallest as weakest iduced dipole
5. Ar exsist as single atoms it has the weakest induced dipole dipole forces of all non-metal so lowest meting point

Question 15

Trend in ionisation energy across P2? (6 marker)

Answer 15

STAGE 1
General increase in IE
same shielding as same number of shells
greater attraction between nucleus and outer e-
STAGE 2
B lower than Be
outer e- in 2P
higher in energy than 2S
STAGE 3
O lower than N
2 e- in 2P needed to be pair
e- pair repulsion

Question 16

Write equation for the 1st ionisation energy of Mg

Answer 16

Mg(g) —> Mg+(g) + e-

Question 17

How does reactivity with water change down group 2

Answer 17

Increases (Mg least—> Ba most)
As outer e- further from nucleus
more shielding

Question 18

Write an equation for the reaction of Ba and water

Answer 18

Ba(s) + 2H20(I) –> Ba(OH)2(Aq) + H2

Question 19

Write an equation for reaction of Mg and steam

Answer 19

Mg(s) + H2O(g) —> MgO(s) +H2(g)

Question 20

What is the trend in hydroxide solubility down G2?

Answer 20

Increases down the group
Mg(OH)2 is almost insoluble
Ba(OH)2 creates a strong alkaline solution

Question 21

What is the trend in sulphate solubility down G2?

Answer 21

Decreases down group
MgSO4 is soluble
BaSO4 is insoluble

Question 22

Write the equations for the extraction of Titanium using Mg

Answer 22

TiO2 +2Cl2 +C —> TiCL4 + CO2
TiCl4(l) + 2Mg(s)—–> 2MgCl2 + Ti

Question 23

What are flue gases?

Answer 23

gases produced by power stations which are harmful to the environment

Question 24

How can CaO or CaCO3 be used to remove flue gases? (equation)

Answer 24

CaCO3(s) + SO2(g) —> CaSO3 (s) + CO2(g)
CaO(s) + SO2(g) —> CaSO3(s)

Question 25

What is Ca(OH)2 used for?
write equations related to one of its uses

Answer 25

neutralise soil
Ca(OH)2(aq) + 2HCl(aq)—-> 2H2O(I) + CaCl2 (aq)

Question 26

What is Mg(OH)2 used for?

Answer 26

Antacid to traet digestion
heartburn

Question 27

What is a use of BaSO4? Why is this safe?

Answer 27

In barium metals to outline gut in X-rays
Ba2+ is toxic but is fine as barium sulphate is insoluble

Question 28

How can BaCl2 be used to test for sulphate ions?

Answer 28

Add HCl , white ppt form =+ve
Ba”+ + SO4 2- —–> BaSO4

Question 29

What happens to the 1st ionisation energy as you go down group 2? why?

Answer 29

increases down the group
increases shielding
increases atomic radius
weaker force between outer e- and nucleus
less energy needed to remove e-

Question 30

Test for SO4 2- IONS

Answer 30

BaCl2
White ppt formed
Ba2+(aq) + SAO4 2-(aq) ————> BaSO4 (s)

Question 31

Use of Mg(OH)2

Answer 31

Neutralize stomach acid