Chemistry P1

Question 1

What is a compound?

Answer 1

A substance containing two or more different types of atoms chemically bonded

Question 2

What is the conservation of mass?

Answer 2

Atoms can neither be created or destroyed in a reaction - equations must be balanced

Question 3

What is a mixture?

Answer 3

A mixture consists of different substances not chemically bonded e.g. air

Question 4

What does filtration remove?

Answer 4

Filtration removes large, insoluble particles from a liquid e.g. sand from water

Question 5

What is crystallisation?

Answer 5

When evaporation leaves behind crystals of a dissolved substance (solute) if heated gently

Question 6

What is distillation?

Answer 6

Distillation involves condensing the evaporated solvent and collecting it (heating the solution so it evaporates, the gases cool and condenses back to a liquid)

Question 7

What’s fractional distillation?

Answer 7

Heating something (e.g. crude oil) until it evaporates, the different liquids separate due to their boiling points

Question 8

What is chromatography?

Answer 8

Chromatography causes substance to rise up paper due to capillary action. Lighter particles move further up

Question 9

What did JJ Thomson discover and make?

Answer 9

He discovered that atoms are made up of positive and negative charges, he came up with the ‘plum pudding’ model (A positive charge, with lots of little electrons around it)

Question 10

What did Ernest Rutherford discover and how?

Answer 10

He discovered that the nucleus was small and positively charged by finding that most alpha particles went strait through a gold ‘leaf’; very few deflected back - Proving that atoms must be mainly empty space

Question 11

What did Neils Bohr discover?

Answer 11

He discovered that electrons exist in shells, orbiting the nucleus

Question 12

What did James Chadwick discover?

Answer 12

He discovered that the nucleus must contain neutrons as well as protons

Question 13

What is the atomic number?

Answer 13

The bottom number, how many protons in a nucleus. An atom must also have this number of electrons in order to be neutral. If not, it is an ion instead

Question 14

What is the mass number/ relative atomic mass?

Answer 14

Mass number is the number of protons + neutrons in a nucleus

Question 15

What is an isotope?

Answer 15

Isotopes are the same element but with a different number of neutrons

Question 16

Why are some mass numbers not whole numbers?

Answer 16

Some masses are not whole numbers because these are an average mass of all isotopes

Question 17

How do you find the average mass of an isotope?

Answer 17

Average mass = Total mass of 100 atoms / 100

Question 18

How was the periodic table initially ordered?

Answer 18

The elements were initially ordered according to their atomic ‘weight’

Question 19

What did Dmitri Mendeleev do?

Answer 19

He realised it made more sense to swap the order of some elements and made the groups, based on their properties

Question 20

What are the max amount of electrons for the first 4 shells of an atom?

Answer 20

Electron shells fill up in the order 2,8,8,2

Question 21

What do metals always do?

Answer 21

Metals always donate electrons to gain an empty outer shell to form positive ions

Question 22

What do non-metals always do?

Answer 22

Non-metals always accept electrons to gain a full outer shell. They can form negative ions or can share electrons to do this

Question 23

What do the group numbers represent?

Answer 23

They represent the number of electrons in the outer shell

Question 24

What are the atoms in group 1 called and what are their properties?

Answer 24

Group 1 are the alkali metals (as they react with water to produce an alkali). They all lose/donate their outer electrons so their ions are all (1)+ e.g. Na+

Question 25

What happens to the properties of the atoms as you go up in groups?

Answer 25

They get more reactive down the groups as the outer electron is further from the nucleus so is donated more readily (the force of attraction is less)

Question 26

What are the atoms in group 7 called and what are their properties?

Answer 26

Group 7 are the halogens. They form (1)- ions as they accept 1 electron to gain a full outer shell. They get less reactive down the group (and boiling point increases)

Question 27

What are the atoms in group 0/8 called and what are their properties?

Answer 27

They are the noble gases, they are very unreactive as they already have an empty/ full outer shell

Question 28

What is metallic bonding?

Answer 28

How metal atoms bond to each other, they form a lattice (grid) of ions surrounded by a 'sea' of delocalised electrons

Question 29

Why are metals good conductors of electricity and heat?

Answer 29

This is because the electrons are free to move (delocalised)

Question 30

What is ionic bonding?

Answer 30

How metals bond to non-metals, metal atoms donate electrons to non-metals to form ions

Question 31

What do the charges of all ions in an ionic compound add up to?

Answer 31

The charges must add up to 0

Question 32

How are ionic structures arranged and what are their properties?

Answer 32

Ions are arranged in a lattice of repeating units of positive and negative ions, these form a crystal. They have high melting/boiling points due to the strong ionic bonds. They can conduct electricity when molten or in a solution, this is because the ions are free to move in these states, and they carry charge

Question 33

What are cations and anions?

Answer 33

Positive ions (+) are also known as cations. 'Cations are Purr-setive' - to remember. Anions are also known as negative ions (-)

Question 34

What is covalent bonding?

Answer 34

How non-metals bond to each other, atoms share electrons to gain full outer shells

Question 35

Can covalent bonded atoms conduct electricity?

Answer 35

No not at all, not even as a liquid

Question 36

What is an allotrope and what is are 2 allotropes of carbon?

Answer 36

Allotropes - Structures made of the same element but arranged differently Diamond and Graphite are allotropes of carbon

Question 37

Why are alloys stronger then pure metal?

Answer 37

Alloys are mixtures of metals: different size atoms disrupt the lattice, so layers cannot slide over each other easily

Question 38

What are Fullerenes/ Nanotubes used for?

Answer 38

Electronics, composites, medical purposes

Question 39

What is relative formula mass?

Answer 39

The sum of the atomic masses in a compound

Question 40

What is the formula with moles, mass and Mr/Ar

Answer 40

Moles = Grams / Rams = Mass (g) / relative atomic/formula mass

Question 41

What is the order of the reactivity series and the mnemonic to remember it ?

Answer 41

Please - Potassium Stop - Sodium Calling - Calcium Me - Magnesium A - Aluminium Crazy - Carbon Zebra - Zinc Instead - Iron Try - Tin Learning - Lead How - Hydrogen Copper - Copper Saves - Silver Gold - Gold

Question 42

What do metal carbonates react with acids to produce?

Answer 42

Salt, carbon dioxide & water

Question 43

What do metals react with acids to produce?

Answer 43

A salt and hydrogen

Question 44

When does a displacement reaction occur?

Answer 44

When a more reactive metal displaces (kicks out) a less reactive metal from a compound

Question 45

How can we obtain metals from ores using displacement and where do ?

Answer 45

Displacing the metal with a more reactive, less valuable metal or carbon

Question 46

What is oxidation and reduction in terms of electrons, and what is the mnemonic?

Answer 46

Oxidation Is Loss Reduction Is Gain

Question 47

What is produced when an acid reacts with an alkali?

Answer 47

A salt and water are produced

Question 48

What is neutralisation?

Answer 48

When an acid (pH<7) reacts with an alkali (pH>7) a salt and water (pH=7) are produced, if reacted completely

Question 49

What is electrolysis?

Answer 49

Passing an electrical current through a substance to cause oxidation and reduction at the two electrodes: the anode (+) and cathode (-)

Question 50

What is required for electrolysis to work?

Answer 50

The ions have to be free to move to the electrode they're attracted to, so for ionic compounds this can only happen when molten or in solution

Question 51

What is an endothermic reaction

Answer 51

When the energy of the products are lower than the energy of the reactants

Question 52

What is an exothermic reaction

Answer 52

When the energy of the products are higher than the energy of the reactants