Topic 6

Question 1

How are elements arranged in the periodic table.

Answer 1

Groups
Periods
increasing atomic number

Question 2

What group of the periodic table are alkali metals in?

Answer 2

Group 1

Question 3

Two properties of alkali metals

Answer 3

Soft

Relatively low melting points

Question 4

Why are they called alkali metals?

Answer 4

They react with water to form alkaline solutions (pH more than 7).

Question 5

Products of lithium and water?

Answer 5

Lithium hydroxide + hydrogen

Question 6

Balanced equation of sodium and water

Answer 6

2Na + 2H2O -> 2NaOH + H2

Question 7

What would we see when lithium reacts with water.

Answer 7

Slowest reaction of alkali metals
Bubbles of hydrogen are produced
Doesn’t melt.

Question 8

Order of reactivity of first 3 alkali metals with water.

Answer 8

Lithium < Sodium < Potassium

Question 9

Trend of reactivity in group 1

Answer 9

Reactivity increases down group 1

Question 10

Why does reactivity increase down group 1?

Answer 10

Number of electron shells increase down the group so more electron shielding. weaker attraction between electron and nucleus, so easier to remove outer shell electron to positive ion.

Question 11

What group are halogens in?

Answer 11

Group 7, as they have 7 outer shell electrons

Question 12

Colour and state of chlorine at room temp?
Colour and state of Bromine at room temp?
Colour and state of Iodine at room temp?

Answer 12

Pale green and gas
Red brown liquid
Black solid

Question 13

What is the trend of melting and boiling point of halogens?

Answer 13

As you go down the group, melting an boiling point increases

Question 14

Why does melting and boiling point increase down group 7?

Answer 14

Molecules get bigger down the group, more intermolecular forces to overcome melting/boiling point, more energy required.

Question 15

Chemical test for chlorine

Answer 15

Damp litmus paper placed in tube of gas, if chlorine present, litmus paper turns red then white due to the bleaching effect of chlorine.

Question 16

Halogens are diatomic, what does that mean?

Answer 16

Form molecules consisting of 2 atoms.

E.g Cl2 O2 and Br2

Question 17

What is produced when a halogen reacts with a metal?

Answer 17

Metal halide salt

Question 18

Balanced symbol equation of reaction between bromine and sodium.

Answer 18

Br2 + 2Na -> 2NaBr

Question 19

Word equation for reaction between iodine and potassium.

Answer 19

Iodine + potassium -> Potassium Iodide

Question 20

Describe trend of reactivity of halogens

Answer 20

Reactivity decreases down group 7

Question 21

Chlorine reacts with hydrogen in sunlight but bromine requires a flame. Why?

Answer 21

Reactivity decreases down the group so bromine requires more energy for reaction to occur.

Question 22

What happens when a hydrogen halide dissolves in water?

Answer 22

An acidic solution, hydrogen ions dissociate, making solution acidic

Question 23

When does halogen displacement occur?

Answer 23

When more reactive halogen displaces less reactive halogen from an aqueous solution of its halide.

Question 24

Word equation of reaction between chlorine and potassium bromide.

Answer 24

Chlorine + potassium bromide -> potassium chloride + bromine

Question 25

Why does reactivity decrease down group 7

Answer 25

Further down outer shell is further away from nucleus, electron shielding increases, attraction between nucleus and outer electrons decreases so harder for atom to gain electron so reactivity decreases.

Question 26

What colours are solutions of chlorine bromine and iodine?

Answer 26

Chlorine in water - colourless Bromine in water - orange Iodine in water - brown

Question 27

What would you observe when chlorine is added to potassium bromide.

Answer 27

Colour change from colourless to orange | Cl2 + 2KBr -> Br2 + 2KCL

Question 28

What is a redox reaction?

Answer 28

A reaction where oxidation and reduction take place at same time.

Question 29

Are halogen displacement reactions redox reactions? Explain.

Answer 29

Yes as the halide ion is oxidised (loses and electron) to from halogen atom while the halogen atom is reduced gains an electron) to become a halide ion.

Question 30

Write 2 half equations for reaction of chlorine and potassium bromide. tell me which is reduction and which is oxidation.

Answer 30

Overall equation: Cl2 + 2KBr -> Br2 + 2KCl Reduction: Cl2 + 2e- -> 2Cl- Oxidation: 2Br- -> Br2 + 2e-

Question 31

What names describe group 0 in periodic table?

Answer 31

Noble gases

Question 32

How many electrons do noble gases have in outer shell?

Answer 32

0 | They have no incomplete shells of electrons.

Question 33

What does chemically inert mean?

Answer 33

Not chemically active.

Question 34

Why are noble gases chemically inert.

Answer 34

Because they have a full outer shell of electrons. So its very stable and means the elements are very unreactive.

Question 35

What properties of helium make it suitable for use in balloons.

Answer 35

less dense than air and does not burn.

Question 36

Why is argon useful to fill electric light bulbs.

Answer 36

Very chemically inert so doesn't react when bulb gets hot and non flammable.

Question 37

Why is argon used for welding

Answer 37

It provides inert welding atmosphere. Argon is more dense than air so it keeps air away from metal.

Question 38

Trend in boiling points down group 0?

Answer 38

Boiling point increases down group 7 because relative atomic mass increases so there is more intermolecular forces between atoms.

Question 39

Trend of density down group 0

Answer 39

Density increases down the group.