topic 7

Question 1

What would you call an element in group 1 of the periodic table?

Answer 1

Alkali metal

Question 2

What would you call an element in group 7 of the periodic table?

Answer 2

Halogen

Question 3

What would you call an element in group 0 of the periodic table?

Answer 3

Noble gas

Question 4

What are 2 properties of alkali metals? (group 1)

Answer 4

• soft
• relatively low mp and bp

Question 5

Describe the reaction of lithium with water

Answer 5

lithium floats, fizzes steadily and becomes smaller, until it eventually disappears.

lithium + water → lithium hydroxide + hydrogen

2Li(s) + 2H2O(l) → 2LiOH(aq) + H2(g)

Question 6

Describe the reaction of sodium with water

Answer 6

sodium melts to form a ball that moves around on the surface. It fizzes rapidly before it disappears.

sodium + water → sodium hydroxide + hydrogen

2Na(s) + 2H2O(l) → 2NaOH(aq) + H2(g)

Question 7

Describe the reaction of potassium with water

Answer 7

the metal melts and floats. It moves around very quickly on the surface of the water. The metal self-ignites. This results in sparks and a lilac flame. There is sometimes a small explosion at the end of the reaction.

potassium + water → potassium hydroxide + hydrogen

2K(s) + 2H2O(l) → 2KOH(aq) + H2(g)

Question 8

What is the pattern of reactivity for alkali metals?

Answer 8

The more electron shells (so the lower in the periodic table) the more reactive the metal

Question 9

What is the colour and physical state of chlorine at room temperature?

Answer 9

pale green gas

Question 10

What is the colour and physical state of bromine at room temperature?

Answer 10

brown/orange liquid

Question 11

What is the colour and physical state of iodine at room temperature?

Answer 11

Grey solid

Question 12

Describe the trend of physical properties of halogens

Answer 12

The more electron shells (so the lower in the periodic table), the higher the boiling point and the darker the colour

Question 13

Describe the chemical test for chlorine

Answer 13

damp litmus paper, turns from blue to white (bleached)

Question 14

Describe the trend in reactivity for halogens

Answer 14

the lower down in the group, the less reactive the halogen (so fluorine is most reactive)

Question 15

What do hydrogen halides form when dissolved in water?

Answer 15

acidic solutions

Question 16

When potassium chloride and bromine are mixed, what would the products be?

Answer 16

No reaction would occur as chlorine is more reactive than bromine, so the products would be the same as the reactants.

Question 17

Why are noble gases inert?

Answer 17

They are in group 0, therefore they have a full outer shell, so they are stable and do not need to gain or lose electrons.

Question 18

Describe some uses of specific noble gases (give 2)

Answer 18

Argon: filament lamps non-flammable

Helium: balloons

Question 19

Describe the trend in physical properties of noble gases

Answer 19

As you go down Group 0, the density, melting points, and boiling points all increase.

Question 20

Define redox reaction

Answer 20

A chemical reaction in which electrons are lost from one substance (oxidation) and added to another (reduction). Oxidation and reduction always occur together.

Question 21

Mean rate of reaction =

Answer 21

quantity of product formed / time taken

Question 22

How do reactions occur?

Answer 22

particles of the reactants must collide, when they collide, they must have enough energy for a reaction to occur, the minimum energy needed for a successful collision (so that products form) is the activation energy

Question 23

When would the rate of reaction increase?

Answer 23

When the frequency of collisions increases

Question 24

List the 5 things that can be done to speed up the rate of reaction

Answer 24

• Increase temperature
• Increase concentration
• Imcrease surface area (solid)
• Increase pressure (gas)
• Add a catalyst

Question 25

Define catalyst

Answer 25

A substance that speeds up the rate of a reaction without altering the products of the reaction, being itself unchanged chemically and in mass at the end of the reaction

Question 26

How does a catalyst increase the rate of a reaction?

Answer 26

By lowering the activation energy of the reaction

Question 27

Define exothermic reaction

Answer 27

A reaction in which heat energy is given out

Question 28

Define endothermic reaction

Answer 28

A reaction in which heat energy is taken in

Question 29

Define activation energy

Answer 29

The amount of energy that the particles of the reactants required for a reaction to occur

Question 30

Describe the reaction profile for an exothermic and endothermic reaction (include temperature change)

Answer 30

Exothermic: negative temperature change

Endothermic: positive temperature change

Question 31

Breaking of bonds is ___________

Answer 31

endothermic

Question 32

Making of bonds is __________

Answer 32

exothermic

Question 33

Energy change =

Answer 33

Energy of bond breaking - energy of bond making