Entire chemistry paper 1

radius of an atom?

1 × 10^-10m

What’s the top number of an element? Bottom number?

top: mass number - protons + neutrons

bottom: atomic number - protons and electrons

isotope definition

atoms of the same element with the same amount of protons but different number of neutrons

mixture and compound definition

mixture - not chemically joined

compound - chemically joined

difference between filtration and crystallisation

filtration - separation of a insoluble solid from a liquid

crystallisation - separation of a soluble solid from a liquid by evaporation

difference between simple distillation and fractional distillation

sd - separation of a liquid from a mixture. Evaporation followed by condensation

fd - separation of different liquids from a mixture of liquids. Substances have different boiling points.

Examples of a reaction having a change in mass

1 - a metal reacts with oxygen and the mass of the oxide produced is greater than the mass of the metal

2 - thermal decompositions of the metal carbonate carbon dioxide is produced and escapes into atmosphere leaving the metal oxide as the only solid product

conservation of mass method

1. weight the test tube and add metal carbonate

2. weight the test tube again

3. heat, cool, and weight the test tube with the metal oxide

4. repeat until no change in mass

5. determine the mass of metal carbonate used and carbon dioxide produced

6. repeat with different metal carbonates

development of the atom stages

1808: dalton believed they were tiny undividable spheres

1897: JJ thompson discovered electrons - plum pudding model (ball of positive charge with negative electrons embedded)

1909: rutherford - alpha particle scattering experiment - mostly empty space with a a positive charged centre

Bohr: electron shells

Further experiments; rutherford found nucleus can be divided - protons. Chadwick discovered neutrons - nuclear model

difference between relative formula mass and relative atomic mass

fm - mass n umber x number of atoms

am - (mass x abundance%) + (mass x abundance%) / 100

limitations of the three state of matter model

1. not solid spheres - atoms, ions or molecules

2. doesn’t show the forces of attraction

3. don’t show 3D spatial arrangement of particles

types of chemical bonding

ionic - metal and non metal, transfer of electrons from the metal to non metal (force of attraction between oppositely charged ions)

covalent - non metal, share electrons

metallic - metal, sea of delocalised electrons

properties of ionic bonding

high melting and boiling points - large amount of energy needed to break the strong electrostatic forces of attraction with oppositely charged ions

conduct electricity when molten or in solution - ions are free to move so charge can flow

properties of diamond

giant covalent bond

giant lattice - carbon atom bonded to four others

high melting point - lots of energy needed to break

hard - strong bonds

doesn’t conduct electricity - no delocalised electrons

used for heavy duty drill parts, jewellery, cutting tools

properties of graphite

giant covalent bond

hexagonal rings - three covalent bonds with three carbon atoms

high melting point - lot of energy needed to break

soft and slippery - weak intermolecular forces between layers, no covalent bonds between layers

can conduct electricity - one electron from each carbon is delocalised

used in pencils and as a lubricant

properties of fullerenes

giant covalent bond

ball shaped - buckminsterfullerenes or carbon nanotubes, hexagonal carbon rings

low melting point - not a lot of energy needed - weak intermolecular forces between molecules

good catalyst - high sa:v ratio due to tiny size

cannot conduct electricity - delocalised electrons cannot move between molecules

C60 - delivers medicinal drugs into body due to hollow shape Nanotubes - nanotechnology, electronics and materials

properties of graphene

giant covalent bond

single layer - one atom thick

high melting point - lot of energy needed to break

very high tensile strength - stretched without breaking

can conduct electricity - delocalised electrons

used in electronics due to thin shape and high electric conductivity, reinforce sports equipment high high tensile strength

properties of metallic bonding

positively charged metal ions arranged in a regular pattern in a sea of negatively charged delocalised electrons

high melting and boiling point - strong electrostatic forces between positive ions and delocalised electrons (except mercury)

good conductivity - delocalised electrons are free to move when solid and molten

shiny metal solids

alloy definition

mixture of metals

different atom size makes them harder to slide over each other making them harder than regular metals

how are the elements arranged in the periodic table NOW?

increasing atomic number

why did chemists not agree with mendeleev’s periodic table?

some boxes had two elements

group 1 contained non metals and metals

Mendeleev left spaces

group 1

alkali metals

1 electron in outer shell

soft metals - cut with knife

loses 1 electron to form +1 ion

low density and melting point down the group

highly reactive metal - stored under oil to prevent reaction with O2 or H2O,

down - more reactive, larger, outer electron further from nucleus - easier lost with less attraction

group 7

halogens

7 electrons in outer shell

coloured vapours

melting and boiling point increase as you go down - increasing intermolecular forces

down - less reactive, larger, outer electrons further from nucleus - less easily gain with less attraction

group 0

noble gases

low melting and boiling points

monatomic, colourless, non flammable

full outer shells

unreactive

down - increase in boiling point - atomic mass - increase in intermolecular forces with more electrons

mole equation

mass = molar mass (Mr - relative formular mass) x moles (mol)

avogrados constant

moles → atoms/particles - x 6.02×10²³

atoms/particle → moles - / 6.02×10²³

how do you calculate concentration?

concentration (g/dm³) = amount of solute (g) / volume of solution (dm³)

ratio rule (example 3:2)

work out the 2 part - /3 then x 2

work out 3 part - /2 then x 3

electrolysis definition and PANIC acronym

the splitting of compounds using electricity

Positive is Anode, Negative Is Cathode

reactivity series

potassium

sodium

calcium

magnesium

aluminium

carbon

zinc

iron

tin lead

hydrogen

copper

silver

cold

OILRIG acronym

Oxidisation Is Loss of electrons Reduction Is Gain of electrons

Half equations (oxidisation)

1. write down equation (ion into atom) - CU → CU+2

2. balance - CU → CU+2

3. check charges on each side - CU = 0, CU+2 = -2

4. balance charges using electron (e-) - CU → CU2+ + 2e- (+2-2=0)

half equations (reduction)

1. write equation - Cl2 → Cl-

2. make atoms balanced - Cl2 → 2Cl-

3. check charges on each side - Cl2 = 0, 2Cl- = -2

4. balance charges using electron (e-) - Cl2 + 2e- → 2Cl-

Extraction of metals

Metals above carbon - electrolysis

Metals below carbon and above hydrogen - reduction

Below hydrogen - do not need to be extracted, ooxygenccur native (naturally)

oxygen in oxidisation and reduction

oxidisation - gains oxygen

reduction - looses oxygen