Chemistry

Question 1

What does the atomic number determine?

Answer 1

The atomic number can allow us to identify the number of protons in an element.

Question 2

What does the atomic mass tell us?

Answer 2

The atomic mass determines the total amount of protons and neutrons in an element.

Question 3

What causes an atom to become a negative ion?

Answer 3

If an atom gains electrons, it is considered a negative ion or ‘anion’.

Question 4

What causes an atom to become a positive ion?

Answer 4

When an atom loses an electron, it becomes a positive ion or ‘cation’.

Question 5

What is graphite an example of?

Answer 5

Graphite is a non-metal.

Question 6

What is the purpose of a pH scale?

Answer 6

The pH scale measures the amount of hydrogen (H+) ions in a solution to determine whether it is acidic or basic.

Question 7

What pH does an acid have?

Answer 7

An acid has a pH less than 7.

Question 8

What pH does a base have?

Answer 8

A base has a pH level over 7.

Question 9

What are some properties of acids?

Answer 9

Acids:

• have a pH less than 7
• turns blue litmus paper red
• releases hydrogen ions into solution
• are corrosive

Question 10

What are some properties of bases?

Answer 10

Bases:

• have a pH more than 7
• turns red litmus paper blue
• releases hydroxide ions into solution
• are caustic or corrosive

Question 11

What is an alloy?

Answer 11

An alloy is a metal made by combining two or more metallic elements. E.g. brass, steel and copper.

Question 12

What is a metalloid?

Answer 12

A metalloid is an element whose properties are a mix of both metals and non-metals. E.g. boron, silicon and arsenic

Question 13

What is an element?

Answer 13

An element is a substance made up of one type of atom.

Question 14

What is an allotrope?

Answer 14

Allotropes are the different physical forms in which an element can exist ie. diamond, graphite and charcoal are allotropes of carbon.

Question 15

What does it mean when a substance is called ‘ductile’?

Answer 15

Substances which are considered ‘ductile’ can be stretched into wires without breaking. Examples of ductile substances are gold, silver and copper.

Question 16

What happens to the pH of a substance when water is added to it?

Answer 16

The pH will rise since water dilutes the acid - making it more basic. Water also contains hydrogen which what is measured by the pH scale.

Question 17

What is the balanced chemical equation of photosynthesis?

Answer 17

6CO_2 + 6H_2O = C_6 H_12 O_6 + 6O_2

Question 18

What is the worded equation for photosynthesis?

Answer 18

Carbon dioxide + water = glucose + oxygen

Question 19

What is the worded equation for a combustion reaction?

Answer 19

Methane + oxygen = carbon dioxide + water

Question 20

What is the worded equation for corrosion?

Answer 20

Metal + water + oxygen = rust (metal oxide)

Question 21

What is the worded equation of a reaction with acid and carbonate?

Answer 21

Acid + carbonate = salt + water + carbon dioxide gas

Question 22

What is the worded equation for the reaction with acid and metal?

Answer 22

Acid + metal = salt + hydrogen

Question 23

What is the equation for neutralisation?

Answer 23

Acid + base = salt + water

Question 24

How do you find the group that an element belongs to?

Answer 24

You must find the electron configuration of the element and the number of electrons in the outermost shell is its group number.

Question 25

How do you find the period that an element belongs to?

Answer 25

The number of electron shells the element has, determines the period it is in.

Question 26

What is the difference between endothermic and exothermic reactions?

Answer 26

When a reaction is endothermic, it absorbs heat and cools surroundings e.g. melting ice cubes. When a reaction is exothermic, it releases heat and causes the temperature of surroundings to rise e.g. combustion of wood.