GCSE Topic 6 - Periodic table

Question 1

Cation

Answer 1

Positively charge ion, such as Na⁺

Question 2

Anion

Answer 2

Negatively charge ion, such as Cl^-

Question 3

What happens to group 1 metals in a reaction, in terms of electrons?

Answer 3

Group 1 metal atoms lose 1 electron to become a cation with a charge of 1+

Question 4

What happens to group 2 metals in a reaction, in terms of electrons?

Answer 4

Group 2 metal atoms lose 2 electrons to become a cation with a charge of 2+

Question 5

What happens to group 3 metals in a reaction, in terms of electrons?

Answer 5

Group 3 metal atoms lose 3 electron to become a cation with a charge of 3+

Question 6

What happens to group 5 non-metals in a reaction, in terms of electrons?

Answer 6

Group 5 non-metal atoms in a molecule each gain 3 electrons to become a cation with a charge of 3-

Question 7

What happens to group 6 non-metals in a reaction, in terms of electrons?

Answer 7

Group 6 non-metal atoms in a molecule each gain 2 electrons to become a cation with a charge of 2-

Question 8

What happens to group 7 non-metals in a reaction, in terms of electrons?

Answer 8

Group 7 non-metal atoms in a molecule each gain 1 electron to become a cation with a charge of 1-

Question 9

Oxidation, in terms of electrons

Answer 9

Loss of electrons

Question 10

Reduction, in terms of electrons

Answer 10

Gain of electrons

Question 11

Redox reaction

Answer 11

A reaction where one substance is oxidised and another substance is reduced.

Question 12

Trend in reactivity of group 1 metals

Answer 12

Reactivity increases down the group

Question 13

Explanation for the trend in reactivity of group 1 metals

Answer 13

This would be a grade 9 answer

• Reactivity increases down the group
• This is because atomic radius increases
• So the distance between the positive nucleus and negative outer electron increases
• Number of shells increases
• So electron shielding increases
• Both of these factors cause the electrostatic attraction between the nucleus and outer electron to decrease
• So the metal atom more easily loses its outer electron
• And is more easily oxidized

Question 14

Symbol equation for the reaction of lithium with water

Answer 14

2 Li _(s) + 2 H₂O _(l) → 2 LiOH _(aq) + H_{2 (g)}

Question 15

Symbol equation for the reaction of sodium with water

Answer 15

2 Na _(s) + 2 H₂O _(l) → 2 NaOH _(aq) + H_{2 (g)}

Question 16

Symbol equation for the reaction of potassium with water

Answer 16

2 K _(s) + 2 H₂O _(l) → 2KOH _(aq) + H_{2 (g)}

Question 17

Symbol equation for the reaction of sodium with oxygen

Answer 17

2 Na _(s) + O_{2 (g)} → Na₂O _(s)

Question 18

Symbol equation for the reaction of potassium with oxygen

Answer 18

2 K _(s) + O_{2 (g)} → K₂O _(s)

Question 19

Symbol equation for the reaction of magnesium with oxygen

Answer 19

2 Mg _(s) + O_{2 (g)} → 2 MgO _(s)

Question 20

Symbol equation for the reaction of sodium with chlorine

Answer 20

2 Na _(s) + Cl_{2 (g)} → 2 NaCl _(s)

Question 21

Symbol equation for the reaction of potassium with chlorine

Answer 21

2 K _(s) + Cl_{2 (g)} → 2 KCl _(s)

Question 22

Type of reaction between a metal and a non-metal

Answer 22

Redox reaction

Question 23

pH of a potassium hydroxide solution

Answer 23

pH 12 to 14

Strongly alkaline

Question 24

Ion that makes solutions alkaline

Answer 24

Hydroxide ion

OH^- _(aq)

Question 25

Half equation for the reactions of sodium

Answer 25

Na → Na⁺ + e^-

Question 26

Half equation for the reactions of chlorine

Answer 26

Cl₂ + 2 e^- → 2 Cl^-

Question 27

Observations for the reaction of lithium with water

Answer 27

* Effervescence * Lithium floats on the surface (it has half the density of water)

Question 28

Observations for the reaction of sodium with water

Answer 28

* Effervescence * Sodium melts into a ball

Question 29

Observations for the reaction of potassium with water

Answer 29

* Effervescence * Potassium melts into a ball * Lilac flame (the reaction is highly exothermic, causing the hydrogen gas to ignite)

Question 30

Trend in melting points of group 1 metals

Answer 30

Decreases down the group The metals can be cut with a knfe

Question 31

Explanation for the trend in melting points of alkali metals

Answer 31

* Melting points decrease down the group * This is because metallic bond strength decreases * Metallic bonding is the electrostatic attraction between the cations and sea of delocalised electrons * This electrostatic attraction gets weaker from Li to Na to K * Because the charge density decreases * As the charge stays the same but the atomic radius increases

Question 32

Colour of potassium hydroxide solution with universal indicator

Answer 32

Blue

Question 33

Compare the reactivity of the alkali metals with water

Answer 33

* General equation is 2 M _(s) + 2 H₂O _(l) à 2 MOH _(aq) + H_{2 (g)} , where M is a group 1 metal * Lithium, sodium and potassium all effervesce as hydrogen gas is produced * They all react with water to produce a soluble hydroxide * And strongly alkaline solution of pH 12 to pH14 owing to production of the hydroxide, OH^- ion * Sodium and potassium melt into a ball * Potassium reacts with water to produce a lilac flame * Reactivity increases from Li to Na to K * The reactions get progressively more exothermic * The reaction between potassium and water is sufficiently exothermic to ignite the hydrogen gas produced

Question 34

Number of available electron shells for a sodium ion

Answer 34

Seven

Question 35

Number of occupied electron shells for a sodium ion

Answer 35

Two

Question 36

Number of occupied electron shells for a sodium atom

Answer 36

Three

Question 37

Colour of fluorine

Answer 37

Yellow

Question 38

Colour of chlorine

Answer 38

yellow-green

Question 39

Colour of bromine

Answer 39

orange-red

Question 40

Colour of solid iodine

Answer 40

shiny black solid

Question 41

Colour of aqueous iodine

Answer 41

brown

Question 42

Colour of iodine vapour

Answer 42

purple

Question 43

Colour of iodine in hexane

Answer 43

purple

Question 44

Trend in melting point for the halogens

Answer 44

* Increases down the group * Fluorine is a gas * Chlorine is a gas * Bromine is a liquid * Iodine is a solid

Question 45

Explanation for the trend in melting point for the halogens

Answer 45

* Intermolecular forces become greaterr from F₂ to I₂ * More thermal energy is required to overcome these forces

Question 46

Trend in reactivity for the halogens

Answer 46

Decreases down the group

Question 47

Explanation for the trend in reactivity of the halogens

Answer 47

This would be a grade 9 answer * Reactivity DECREASES down the group * This is because atomic radius increases * So the distance between the positive halogen nucleus and the negative outer electron of a NEIGHBOURING atom increases * Number of shells increases * So electron shielding increases * Both of these factors cause the electrostatic attraction between the halogen nucleus and the negative outer electron of a NEIGHBOURING atom increases * So the non-metal atom LESS easily gains an electron * And is LESS easily reduced

Question 48

Symbol equation for the reaction of fluorine with potassium chloride

Answer 48

F_{2 (g)} + 2 KCl _(aq) → Cl_{2 (g)} + 2 KF _(aq) There will be NO colour change. Potassium iodide is colourless and chlorine gas dissolves in water to make a colourless solutuion, unlike bromine and iodine.

Question 49

Symbol equation for the reaction of chlorine with potassium bromide

Answer 49

Cl_{2 (g)} + 2 KBr _(aq) → Br_{2 (l)} + 2 KCl _(aq) There will be a colour change from colourless to orange. Note that the bromine that is produced will be dissolve in water to produce an orange solution.

Question 50

Symbol equation for the reaction of chlorine with potassium iodide

Answer 50

Cl_{2 (g)} + 2 KI _(aq) → I_{2 (s)} + 2 KCl _(aq) There will be a colour change from colourless to brown. Note that the iodine that is produced will be dissolve in water to produce a brown solution.

Question 51

Symbol equation for the reaction of bromine with potassium iodide

Answer 51

Br_{2 (l)} + 2 KI _(aq) → I_{2 (s)} + 2KBr _(aq) There will be a colour change from colourless to brown. Note that the iodine that is produced will be dissolve in water to produce a brown solution.

Question 52

Ionic equation for the reaction of fluorine and potassium chloride

Answer 52

F_{2 (g)} + 2 Cl^- _(aq) → Cl_{2 (g)} + 2 F^- _(aq) Only the molecules and ions involved in the reaction appear in the ionic equation. The other ions are spectator ions and do not take place in the reaction. These reactions are redox reactions. The more reactive halogen is reduced, the less reactive halogen is oxidized.

Question 53

Ionic equation for the reaction of chlorine and potassium bromide

Answer 53

Cl_{2 (g)} + 2 Br^- _(aq) → Br_{2 (l)} + 2 Cl^- _(aq) Only the molecules and ions involved in the reaction appear in the ionic equation. The other ions are spectator ions and do not take place in the reaction. These reactions are redox reactions. The more reactive halogen is reduced, the less reactive halogen is oxidized.

Question 54

Ionic equation for the reaction of chlorine and potassium iodide

Answer 54

Cl_{2 (g)} + 2 I^- _(aq) → I_{2 (s)} + 2Cl^- _(aq) Only the molecules and ions involved in the reaction appear in the ionic equation. The other ions are spectator ions and do not take place in the reaction. These reactions are redox reactions. The more reactive halogen is reduced, the less reactive halogen is oxidized.

Question 55

Ionic equation for the reaction of bromine and potassium iodide

Answer 55

Br_{2 (l)} + 2 I^- _(aq) → I_{2 (s)} + 2Br ^- _(aq) Only the molecules and ions involved in the reaction appear in the ionic equation. The other ions are spectator ions and do not take place in the reaction. These reactions are redox reactions. The more reactive halogen is reduced, the less reactive halogen is oxidized.

Question 56

Half equation for fluorine

Answer 56

F_{2 (g)} + 2 e^- → 2 F^- _(aq) These reactions show what is happening in terms of electrons. Only ONE halogen appears in this equation. Each halogen atom in a halogen molecule gains one electron to become a halide 1- ion.

Question 57

Half equation for chlorine

Answer 57

Cl_{2 (g)} + 2 e^- → 2 Cl^- _(aq) These reactions show what is happening in terms of electrons. Only ONE halogen appears in this equation. Each halogen atom in a halogen molecule gains one electron to become a halide 1- ion.

Question 58

Half equation for bromine

Answer 58

Br_{2 (l)} + 2 e^- → 2 Br^- _(aq) These reactions show what is happening in terms of electrons. Only ONE halogen appears in this equation. Each halogen atom in a halogen molecule gains one electron to become a halide 1- ion.

Question 59

The least reactive group of elements

Answer 59

Noble gases NOT Nobel gases

Question 60

This noble gas reacts with fluorine

Answer 60

Xenon Xenon tetrafluoride is formed, XeF₄

Question 61

This noble gas is the least reactive element

Answer 61

Helium

Question 62

Explanation for the low reactivity of the noble gases

Answer 62

The atoms have a full outer shell of electrons

Question 63

Uses of noble gases

Answer 63

* Flammable or highly reactive liquids are placed in a container with an atmosphere of a noble gas * Fill balloons with helium as its density is a lot less than the density of air

Question 64

Trend in boiling point for the noble gases

Answer 64

Increases down the group