Groups in the Periodic Table

Question 1

What happens when Lithium, sodium and potassium are put in water?

Answer 1

Lithium - move around the surface, fizzing furiously
Sodium and potassium - do the same but melt in the reaction’s heat. Potassium ignites the hydrogen gas being produced

Question 2

What’s the word equation for sodium and water?

Answer 2

Sodium + water –> Sodium hydroxide + hydrogen

Question 3

What are group 1 metals known as?

Answer 3

Alkali Metals

Question 4

What are some characteristics of the Alkali metals?

Answer 4

Properties similar to other metals:
- Malleable
- Conduct electricity

Properties specific to group 1:
Very reactive
Easily cut
Very soft
Low melting point
Readily form compounds with other metals

Question 5

How do you calculate relative atomic mass?

Answer 5

(mass number a x isotope abundance a) + (mass number b x isotope abundance b)
divided by
Isotope abundance a + b

Question 6

What’s an isotope?

Answer 6

Atoms of the same element with the same number of protons and a different number of neutrons

Question 7

What are the products when alkali metals are put in water?

Answer 7

Hydrogen and a metal hydroxide

Question 8

At which point in group 1 is reactivity the highest?

Answer 8

Reactivity increases as you go down the group

Question 9

Explain the trend of reactivity in group 1

Answer 9

• Reactivity increases as you move down the group
• This is because, an extra electron shell is added each period (the atom gets bigger)
• So, the force of attraction between the negatively charged outer electron and positively charged nucleus decreases as they get further apart (electrons are more easily lost the further away they are from the nucleus due to the weaker force of attraction, hence them being more reactive)

Question 10

What are elements in group 7 known as?

Answer 10

Halogens

Question 11

How are the halogens similar?

Answer 11

• diatomic molecules with 2 atoms held together by a single covalent bond
• All non-metallic (poor conductors of heat and electricity)
• Toxic and corrosive

Question 12

How do chlorine, bromine and iodine look?

Answer 12

Chlorine - green gas
Bromine - brown liquid
Iodine - purple/black solid

Question 13

What happens when halogens react with metals?

Answer 13

They form ionic compounds called salts that contain halide ions

Question 14

Chlorine + magnesium —->

Answer 14

Magnesium chloride

Question 15

Name some uses for halide salts

Answer 15

Sodium chloride - table salt
Sodium fluoride - Toothpaste
Sodium bromide - disinfectant for swimming pools
Sodium iodide - added to table salt to prevent iodine deficiency

Question 16

What can all halogens be used for and why?

Answer 16

Disinfectants and bleaches: they can kill microorganisms and remove colour from material

Question 17

How can you test for chlorine gas?

Answer 17

Place damp blue litmus paper in the gas. If it turns red, then bleaches white, the gas is chlorine.

Question 18

How can the reactivity of halogens be determined using displacement reactions?

Answer 18

A more reactive halogen will displace a less reactive halogen from a halide compound

Question 19

Chlorine + sodium bromide —>

Answer 19

Bromine + Sodium chloride
(chlorine is more reactive than bromine, so it displaces it)

Question 20

Explain the order of reactivity of halogens in relation to the electronic configuration

Answer 20

• Reactivity of halogens decrease as you go down the group
• Halogens gain 1 electron to get a full outer shell and become stable
• So, halogens at the top of the group have their outer shells closer to the nucleus meaning the force of attraction between the incoming electron and nucleus is stronger

Question 21

Why are displacement reactions redox reactions?

Answer 21

Both reduction and oxidation occurs in displacement reactions, making them examples of redox reactions

Question 22

What are the elements in group 0 known as?

Answer 22

Noble Gases

Question 23

What are the properties of the noble gases?

Answer 23

• Colourless
• Very low melting and boiling points
• Poor conductors of heat and electricity

Question 24

Explain why noble gases are chemically inert

Answer 24

Atoms gain, lose or share electrons to get a full outer shell and become more stable. Noble gases already have a stable electronic configuration with a full outer shell, so they are unreactive.

Question 25

Explain some uses/examples of Noble Gases

Answer 25

Helium: very low density, non flammable - used in weather balloons and airships

Argon: Denser than air - added to the space above wine in wine bottles to stop the oxygen in the air from reacting with the wine

Krypton: produces a white light when electricity is passed through it - used in photography lighting

Neon: produces a distinctive red-orange light when electricity is passed through it - used in the making of long-lasting illuminated signs

Question 26

Why was the noble gas group not known until the end of the 19th century?

Answer 26

Elements were difficult to detect as they don’t react with anything

Question 27

Describe the trends in the physical properties
of the noble gases

Answer 27

Melting point, density and boiling point increases as you go down the group