Chemistry

Question 1

Covalent bonding involves:
Transferring electrons
or
Sharing electrons

Answer 1

Sharing electrons - atoms share electrons with each other so that they have a full outer shell

Question 2

Covalent bonding involves:
2+ metals
At least 1 metal and 1 non metal
2 non metals

Answer 2

2 non metals - only elements from the right hand side of the periodic table can form covalent bonds with each other

Question 3

Which of the following is a simple molecular substance? You may select more than one answer.

• Graphite
• Water
• Diamond
• Silicon dioxide
• Chlorine

Answer 3

Water and chlorine are the correct answers.

Graphite, diamond and silicon dioxide are giant covalent structures known as macromolecules.

Question 4

Which of the following is true about graphite?
It is a metal
It conducts heat and electricity
It is an ionic substance

Answer 4

Graphite conducts heat and electricity

Question 5

Explain why graphite conducts heat and electricity

Answer 5

Each carbon atom in graphite only forms 3 covalent bonds, therefore each carbon atom has 1 delocalised/free electron - these free electrons conduct heat and electricity

Question 6

What state is bromine at room temperature?
A. Gas
B. Solid
C. Liquid

Answer 6

C. Liquid - it’s melting point is -7C

Question 7

Which of the following is true about group 7 halogens?
A. They all have 7 electrons in their outer ring
B. They all have 7 rings of electrons
C. They all have 7 protons in their nucleus

Answer 7

A. They all have 7 electrons in their outer ring

Question 8

Reduction is:
The loss of electrons OR
The gain of electrons

Answer 8

Reduction is the GAIN of electrons.

Remember OIL RIG - Oxidation Is Loss, Reduction Is Gain

Question 9

Does reactivity increase or decrease as you go down group 7?

Answer 9

Reactivity decreases

Question 10

True or false?

When reacting chlorine with potassium iodide, chlorine displaces iodine

Answer 10

True - chlorine is more reactive than iodine, and therefore displaces it

Question 11

True or false?

When reacting bromine with sodium fluoride, bromine displaces fluorine

Answer 11

False - fluorine is more reactive than bromine, so bromine cannot displace it

Question 12

Which of the following will not increase the rate of a reaction?
A. Increased temperature
B. Adding a catalyst
C. Diluting solution
D. Increased surface area

Answer 12

C. Diluting solution - dilute means less concentrated

Question 13

Define the word ‘catalyst’

Answer 13

A catalyst is a substance that speeds up a reaction without being change or used up in the reaction

Question 14

A substance with a pH of 4 is:
Acidic OR
Alkaline

Answer 14

Acidic - pH below 7 is acidic

Question 15

What is a neutralisation reaction?

Answer 15

Neutralisation is when an acid is added to a base, so that they neutralise each other

Question 16

Acid + metal -> ?

A. Alkali + salt
B. Salt + oxygen
C. Oxygen + alkali
D. Salt + hydrogen

Answer 16

D. Salt + hydrogen

Question 17

Which of the following is normally a fast reaction?
Decomposition of hydrogen peroxide
Magnesium + HCl
Copper + HCl

Answer 17

Magnesium + HCl is normally a fast reaction

Question 18

Exothermic reactions:
Release heat
Take heat in

Answer 18

Exothermic reactions release heat

Question 19

Exothermic reactions involves:
Forming new bonds
Breaking bonds

Answer 19

Exothermic reactions involve forming new bonds, as the formation of new bonds releases energy

Question 20

True or false

In an endothermic reaction, the reactants have a higher energy than the products

Answer 20

This is false - in an endothermic reaction, bonds are broken, which requires heat. As heat is needed for the reaction, the products have a higher energy than the reactants.

Question 21

Define the term isotope

Answer 21

Atom of the same element with the same number of protons and electrons, but a different number of neutrons

Question 22

Describe, in terms of electrons, how copper nitrate becomes Cu2+

Answer 22

Copper loses 2 electons

Question 23

Explain why metals are malleable (malleable means they can be moulded into different shapes!)

Answer 23

Metal ions are arranged in sheets. These sheets/layers can slide over each other, meaning they can be moulded into different shapes

Question 24

Why is argon gas used in filament lamps?

Answer 24

Because it is inert - it does not react

Question 25

Sodium chloride is: A. Covalent B. Ionic C. Metallic

Answer 25

B - Ionic Na is a metal and Cl is a non metal, therefore it is an ionic compound

Question 26

A solution of a chloride salt is acidified with dilute nitric acid. Silver nitrate solution is added to the mixture. Describe what is seen when the silver nitrate solution is added.

Answer 26

Silver chloride forms a white precipitate

Question 27

A solution of an iodide salt is acidified with dilute nitric acid. Silver nitrate solution is added to the mixture. Describe what is seen when the silver nitrate solution is added.

Answer 27

Silver iodide forms a yellow precipitate

Question 28

Explain what is meant by the term catalyst

Answer 28

A catalyst speeds up the rate of a reaction, without being used up or changed.

Question 29

What is complete combustion and what are its products?

Answer 29

Complete combustion is when a hydrocarbon burns in oxygen completely. It produces carbon dioxide and water.

Question 30

Is energy gained or lost in an exothermic reaction?

Answer 30

Energy is released as heat and therefore energy is lost.

Question 31

Sodium is a: A. Halogen B. Alkali metal C. Transition metal

Answer 31

Sodium is in group 1 - group 1 metals are also known as alkali metals

Question 32

How many electrons are in the outer shell of chlorine?

Answer 32

Chlorine is in group 7, so it has 7 electrons in it's outer shell. This means it wants to gain 1 electron to become more stable.

Question 33

Explain the trend in reactivity in group 1 metals.

Answer 33

Group 1 metals become more reactive further down the group. This is because, as shells of electrons are added, they receive less shielding from the nucleus and therefore the electrons react more easily. (Think of the nucleus as like a planet exerting gravity on the rings of electrons - the further away the electrons are, the less gravity is exerted on them!)

Question 34

Boron has an atomic number of 5. There are two isotopes of boron, boron-10 and boron-11. How many protons does boron have? And how many electrons?

Answer 34

Boron has 5 electrons and 5 protons. Boron-10 has 5 neutrons, whereas boron-11 has 6 neutrons.

Question 35

Copper is a metal. Copper conducts electricity because particles in it move through the structure. Which particles are these?

Answer 35

Electrons - only electrons conduct electricity

Question 36

Copper forms coloured compounds - what is the name given to the group of metals that form coloured compounds?

Answer 36

Transition metals form coloured compounds

Question 37

When chlorine is bubbled into potassium bromide solution, the solution turns orange. Explain why this happens.

Answer 37

Chlorine displaces bromine as it is more reactive. The orange is due to bromine.

Question 38

Silver nitrate solution can be added to a solution to test for the presence of chloride ions. In this test, dilute nitric acid is added to the solution, followed by the silver nitrate solution. A white precipitate shows the presence of chloride ions. Why must the dilute nitric acid be added to make this a reliable test?

Answer 38

To remove other ions that would also form a white precipitate

Question 39

Explain why increasing the concentration of a reactant increases the rate of the reaction

Answer 39

Increasing the concentration means there are more particles. This means there are more particles available to collide, thus increasing the rate of reaction.

Question 40

Explain why water contains 2 hydrogen atoms to every 1 oxygen

Answer 40

Oxygen is in group 6 - so it needs 2 extra electrons to fill its outer shell. Hydrogen contains 1 electron in its outer shell, so 2 hydrogens will bond to 1 oxygen to form H2O.