Core

Question 1

What is an element?

Answer 1

A substance made of atoms with the same number of protons in the nucleus. Each element has its own chemical symbol, which:

• consists of one, two,or three letters
• starts with a capital letter

Question 2

An atom

Answer 2

Smallest particle of an element that still has its chemical properties

Question 3

What is a molecule?

Answer 3

A molecule consists of two or more atoms chemically joined together

Question 4

A compound

Answer 4

Consists of two or more different elements chemically joined together.
E.g CH4

Question 5

What are the state symbols

Answer 5

Solid(s)
Liquid(l)
Gas(g)
Aqueous solution(aq) - dissolved in water

Question 6

What is an ion?

Answer 6

An ion is an electrically charged particle. It is formed when an atom, or group of atoms lose or gain electrons.

Question 7

Hazards risk and precautions

Answer 7

A hazard is something that could cause damage or harm to something
A risk is the chance that someone or something will be harmed if exposed to an hazard.
Precautions- something you would do to reduce the risk of harm

Question 8

State some hazard symbols

Answer 8

!- harmful or irritant
Flames - flammable 
Broken man- respiratory sensitiser
Skull and crossbones- toxic 
Hand and liquid- corrosive
Ball of fire- oxidising

Question 9

What are isotopes?

Answer 9

Ato es of an element with the same atomic number but a different mass number

Question 10

Abundances equation

Answer 10

Multiply the mass number of the isotope by the abundance (percentage) and add it to the other. Then divide it by 100 to get a percentage

Question 11

What is a cation?

Answer 11

A positively charged ion
Formed when an atom or group of atoms loses electrons
-Group 1 atoms lose 1 electron to form a + ion
-group 2 atoms lose 2 electrons to form a 2+ ion

Question 12

Anions

Answer 12

A negatively charged ion
Formed when an atom or group of atoms gain electrons
Group 7 atoms gain 1 electron making their ion a - ion
Group 6 atoms gain 2 electrons making a 2- iron

Question 13

Ionic bonding

Answer 13

Ionic bonding are strong electrostatic forces of attraction between oppositely charged ions.
E.g. sodium reacts with chlorine to form sodium chloride

Question 14

Covalent bonds

Answer 14

A covalent bond is formed when a pair of electrons is shared between two atoms.
Covalent bonds:
Are strong, form between non-metal atoms

Question 15

Determining empirical formula

Answer 15

Crucible and lid
Magnesium ribbon, tripod
Weigh crucible and lid
Weigh crucible, lid and Mg before heating
Weigh crucible, lid and mg after heating
Minus weight of crucible , lid and mg before heating by start weight to find mass of mg. Mass of oxygen = after heating - before heating

Question 16

What is the conservation of mass

Answer 16

According to the conservation of mass, the total mass of reactants and products stays constant during a chemical reaction.

Question 17

Closed systems

Answer 17

Is a situation in which no substances can enter or leave during a reaction.
Closed systems include:
Reactions in a sealed container such as a flask fitted with a bung
Precipitation reactions in a beaker

Question 18

What happens in a precipitation reaction

Answer 18

Two soluble reactants from an insoluble product- the precipitate
Total mass of beaker and it’s contents stay the same after a precipitation reaction

Question 19

Non-enclosed systems

Answer 19

A situation where substances can enter or leave during a reaction.
Non- enclosed systems include:
Reactions in an open flask, where a substance win the gas state may enter or leave

Question 20

The periodic table

Answer 20

Modern periodic table are arranged in order of atomic numbers
Rows are called periods
Elements with similar properties are placed in the same group(vertically)

Question 21

Relative atomic mass =

Answer 21

Mass(g) over moles

Question 22

1dm3 = 1000cm3

Answer 22

To convert cm3 to dm3 divide by 1000

To convert dm3 to cm 3 multiply 1000

Question 23

Fractions crude oil:

Answer 23

Gases - most flammable, least viscous, lowest boiling point, smallest number of c and h atoms 
Petrol
Kerosene 
Diesel oil
Fuel oil
Bitumen

Question 24

Rates of reaction

Larger piece of solid smaller surface area slower reaction
Larger surface area smaller pieces of solid quicker reaction

Answer 24

Colliding particles with the activation energy or more to be successful
Rate of reaction increases when conc is high, or pressure of gas is high
Temperature. Particles will have a lot of energy end move faster causing collisions
Surface:vol ratio increases rate of reaction.

Question 25

The noble gases

Answer 25

Group 0
Chemically inert because :
Their atoms have full outer electrons so
They have tendency to lose or gain electrons