Periodicity

Question 1

Periodicity

Answer 1

Repeating patterns of chemical, properties reactions

Question 2

Reactivity

Answer 2

S block :reactivity increases down the group
Non-metals -reactivity decreases down the group
Tms-fairly reactive
Lanthanides - similar reactivity - 3+ions
Actinides -radioactivie metals - only th and u occurred naturally in earths crust

Question 3

Trends in period 3

Answer 3

Na mg al -metals giant structures ,lose outer electrons to form ionic compounds
Si-semi metal forms covalent bonds
P,s,cl -non metals ,accepts electrons to form ionic compounds or share electrons to form covalent
Ar-undeactive

Question 4

Trend of group 2 metals in water

Answer 4

reactivity of Group 2 metals with water, is an increase down the group. The outer electrons are easier to remove as they are further from the nucleus and there is more shielding resulting in a lower nuclear attraction.

Question 5

Define the bonding in magnesium

Answer 5

Metallic bonding . Forces of attraction between the sea of delocalised electrons and the positive cations metal atoms (mg2+)

Question 6

Explain in terms of structure and binding why magnesium chloride has a high melting point

Answer 6

Giant ionic lattice between mg2+ and cl- ions strong electrostatic forces of attraction between them.

Question 7

Group 2 alkaline earth metals

Answer 7

S block
Beryllium is not typical of the group so not considered
2 electrons in outer s orbital
Atomic radii increases down the group
Melting point decreases down the group
1st and 2nd ionisation energies decrease down the group

Question 8

SULFATE solubility least to most

Answer 8

Baso4
Caso4
Mgso4

Question 9

Use of baso4

Answer 9

Used in X-rays as barium meals
Barium would be toxic if it entered the blood stream but as it is insoluble it can not be dissolved and can be used as medical tracers

Question 10

Hydroxide solubility least to most

Answer 10

Mg(oh)2
Ca(oh)2
Ba(oh)2

Question 11

Use of mgoh2

Answer 11

Used as an indigestion tablet in o neutralised stomach acid-antacid

Question 12

Use of (oh)2

Answer 12

Used in agriculture
Known as slaked lime
Used to neutralise acidic soils to encourage plant growth

Question 13

Solubility trends

Answer 13

Singly dharged anions increase solubility down the group
Doubly charged anions decrease in solubility down the groups

Question 14

Test for SULFATE ions

Answer 14

Add acidified bacl2 to solution containing SULFATE ions
Whir predicate formed baso4
Acidified with hcl to remove carbonates which also produce white prec

Question 15

Barium SULFATE equation

Answer 15

Ba 2+ +so42- - > baso4

Question 16

Uses of group 2 - titanium

Answer 16

-titanium is used in the aerospace industry and for replacement hips
-not easy to extract usually extract with carbon but this forms titanium carbide and makes the metal brittle
-so titanium oxide is first reacted with chlorine and carbon to from ticl4When meduced eith magnesium’s

Question 17

Titanium reduced with magnesium

Answer 17

Ticl4 + 2mg —->2mgcl2 +ti

Question 18

Calcium oxide and calcium carbonate

Answer 18

1)alkaline slurry -mix capo of caco3 with water
2)wet scrubbing - acidic so2 removed xfrom flue gasses by spraying with slurry
3)calcium sukfate produced

Question 19

Group 7 physical properties

Answer 19

-non metals and don’t conduct electricity
-brittle and crumbly when solid
-poisonous and smells

Question 20

Fluorine

Answer 20

Pale yellow

Question 21

Chlorine

Answer 21

Green yellow gas

Question 22

Bromine

Answer 22

Red brown liquid

Question 23

Iodine

Answer 23

Blue black solid
Darker as you go down the group

Question 24

Atomic radius in halogen

Answer 24

Increases from fluorine to chlorine as number of shells increase so outer shell electrons further away
More energy levels

Question 25

Melting point and boiling point in halogen

Answer 25

They increase , number of electrons increase, ban Dee waal forces increases in strength so more energy needed to overcome them

Question 26

Electro negativity in halogens

Answer 26

Electronegativity decreases from fluorine to iodine Fluorine is the most electronegative More energy levels occupied but nc increases

Question 27

Ionisation energy

Answer 27

Decreases down the group Greater radius more shielding

Question 28

Fluorine anomaly

Answer 28

Small so leads to repulsion between lone electrons because tHey are close together

Question 29

Oxidising ability in halogens

Answer 29

Good ability Their oxidising power decreases down the group Due to greater shielding and atomic radius

Question 30

Displacement reactions

Answer 30

Halogens react with metal halodes in solutions A more reactive halide will displace a less reactive one

Question 31

Extracting group 7

Answer 31

Can extract bromine from sea water Cl2+2br- =br2 +2cl- Extracting iodine from kelp 2I- +mno2 +4h+ = mn2+ +2h2o +i2

Question 32

Chlorine use

Answer 32

-chlorine reacts with cold water to produce chlorine ions and chloride ions -cl2 +h2o = clo- +cl-+2n+ Both oxidise and reduced this is disproportionation In the presence of uv light ,chlorine decomposes water to produce oxygen and hydrophobic acid and chlorine is reduced Used in bleach also disproportionation Chlorine reacts with cold dilute naoh to produce sodium hypochlorite

Question 33

Halides as reducing agents

Answer 33

Halide ions are good reducing agents as they donate electrons to the species being reduced Ability reduce increases Down the group