Section 1 d) Summary

Relative atomic mass (Ar) is the mass of an atom, relative to Carbon, which has an Ar of 12. This is because of the tiny size of atoms, measuring in fractions of a gram would be extremely impractical.

Relative formula mass (Mr) is the total relative mass of a molecule. It is the Ar of each atom in a molecule added together. (e.g. CO2 would be 1 x 12, because there is one carbon, plus 2 x 16, because there are two oxygens, adding to a Mr of 44)

Mr can be used to calculate the mass of a substance that can be obtained from a chemical reaction, or how much of a substance is necessary to neutralise another substance.
This formula triangle is useful in calculating masses:

When the Mr of a substance is equal to the number of grams there are of it, that is one mole. A mole is 6.022 x 10^23 particles. This is called Avagadro's number, or Avagadro's constant.
A mole of gas at room temperature and pressure always takes up 24 dm^3, or 24000 cm^3. 

Section 1 d) Key Words

Ar/Relative Atomic Mass: The mass of a single atom relative to Carbon 12

Avagadro's Number: The number of particles of a substance in 1 mole of it: 6.022 x 10^23

Molar Volume: The volume of space 1 mole of any gas takes up at room temperature and pressure: 24dm^3 or 24000cm^3

Mole: The number of particles it takes for Mr to equal mass in grams. Avagadro's number of particles are in 1 mole.

Mr/Relative Formula Mass: The mass of a molecule relative to carbon 12.

Section 1 d) Specification

1.16 calculate relative formula masses (Mr) from relative atomic masses (Ar)

From the chemical formula of a compound, the Mr can be found by adding the individual relative atomic masses of each atom.
e.g. CO2
C = 12, O = 16
12 + (2 x 16) = 44

1.17 understand the use of the term mole to represent the amount of substance

A mole is the amount of a substance with the same number of molecules as Carbon 12 at a mass of 0.012kg (12g). Otherwise defined as having 6.022 x 10^23 molecules of it.

1.18 understand the term mole as the Avogadro number of particles
(atoms, molecules, formulae, ions or electrons) in a substance

Avagadro's number is how many particles of a substance there must be for its mass in grams to be equal to its relative atomic mass. Avagadro's number is 6.02214154 x 10^23, but at GCSE level we shorten it to 6.022 x 10^23 unless otherwise specified.

1.19 carry out mole calculations using relative atomic mass (Ar) and relative
formula mass (Mr)

The above formula triangle can be used to calculate different parts of a chemical formula.
Examples:

2Ca + O2 --> 2CaO
2mol 1mol    2mol
1 mole of any substance contains the same number of particles.
If we have 5g of Calcium, what mass of Calcium Oxide will we get?
Mass of Ca = 5g       Mr of Ca = 40       5 / 40 = 1 / 8 moles
The ratio of Ca:CaO is 1:1, so there is the same number of moles.
1/8 mol of CaO must be multiplied by its Mr to find the mass
Mr of CaO = 56      56 x 1/8 = 7
There are 7 grams of CaO from 5g Ca.

CuSO4 + Zn --> ZnSO4 + Cu
1mol     1mol     1mol      1mol
If we have 1.5g Zinc,  what mass of Copper will we get?
1.5g / 65 = 3/130 mol
ratio 1:1 so same number of moles
Mr of copper = 63.5
3/130 x 63.5 = 1.47 g

2Fe + 3Cl2 --> 2FeCl3
How much Chlorine is needed to react with 20g of Iron?
20 / 56 = 5/14 mol
ratio is 2:3 so we first divide by 2 to get 5/28
then multiply by 3 to get 15/28
we then find the Mr of Cl2     35.5 x 2 = 71
15/28 x 71 = 38 1/28 g

1.20 understand the term molar volume of a gas and use its values
(24 dm^3 and 24,000 cm^3) at room temperature and pressure (rtp) in
calculations.

1 mole of any gas takes up the volume of 24dm^3 at room temperature and Earth's atmospheric pressure. We can use this in gas calculations to calculate gas volumes, or use it the other way around and find how many moles there are based on its volume. 

Section 1 c) Summary

Atoms are made up of a central nucleus, which has a relative positive charge due to its protons. It also contains neutrons. These make up the entire relative mass of the atom.
This is orbited by negatively charged electrons, which are attracted to the positive nucleus. These electrons make up shells, which have capacity: 2,8,8,8,8,8,8.

An atom has equal numbers of protons and electrons, resulting in no overall charge. Electrons can be transferred to other particles, however, or gained from them. This results in the atom gaining a charge and becoming an ion. A negatively charged ion is called a cation and a positively charged ion is called an anion.

When atoms have the same number of protons but a different number of neutrons, they are called isotopes.

All chemical elements are organised in the periodic table.

It is organised in order of atomic number. It fits into different groups and periods based off properties and characteristics. The properties and reactivity of an element can be predicted by the surrounding elements in the table.
Periods are the rows, Groups are the columns.
The periods can tell us the number of shells each atom has, while the groups tell us the number of outer shell electrons they have.
The basic electronic capacity of the shells is 2, 8, 8, 8

Section 1 c) Key Words

Atom: The smallest chemical particle. Made up of positively charged central nucleus (protons and neutrons) and shells of negatively charged electrons.

Atomic Number: The number of protons in an atom

Electron: Negatively charged subatomic particle with a relative mass of 0. Orbits the nucleus in shells and can be transferred to other atoms to form charged ions.

Group: The vertical organisation of elements in the periodic table. From left to right, there are 8 groups: 1, 2, 3, 4, 5, 6, 7, 0

Ion: A charged chemical particle, an atom that has lost or gained electrons.

Isotope: Atoms with the same number of protons but different numbers of neutrons

Mass Number: Number of protons + Number of neutrons

Nucleus: The central part of an atom comprised of protons and neutrons. Positively charged.

Neutron: A subatomic particle without charge and relative mass 1. Found in the nucleus.

Period: The horizontal organisation in the periodic table, numbers increasing top to bottom.

Periodic Table: A way of organising the chemical elements by atomic number, with patterns relating to reactivity and other properties.

Proton: A positively charged subatomic particle with a relative mass of 1. Found in the nucleus.

Relative Atomic Mass: The mass of an atom, relative to carbon 12.

Valence Electron(s): The electrons found in the outer electron shell.  

Section 1 c) Specification

1.9 understand that atoms consist of a central nucleus, composed of protons
and neutrons, surrounded by electrons, orbiting in shells

An atom is composed of a nucleus, made up of positively charged protons and neutrons, which have no charge. Each of these sub-atomic particles has a relative atomic weight of 1.

The nucleus is surrounded by shells of negatively-charged electrons, which have a relative atomic weight of 1. The shells of an atom are described at GCSE level as the first shell containing 2 electrons, and further shells having a capacity of 8 electrons.

1.10 recall the relative mass and relative charge of a proton, neutron and electron

Proton: Relative mass 1, Relative charge +
Neutron: Relative mass 1, Relative charge 0
Electron: Relative mass 0, Relative charge -

1.11 understand the terms atomic number, mass number, isotopes and relative
atomic mass (Ar)

Atomic Number: The number of protons in an atom
Mass Number: The number of protons + the number of neutrons in an atom
Isotopes: Atoms with the same number of protons and electrons, but a different number of neutrons.
Relative Atomic Mass: The mass of an atom relative to Carbon 12.

1.12 calculate the relative atomic mass of an element from the relative
abundances of its isotopes

(Mass 1 x Abundance 1) + (Mass 2 x Abundance 2) + .....
_________________________________________________
                                           100       

1.13 understand that the Periodic Table is an arrangement of elements in order of
atomic number

The Periodic Table was developed by Mendelev as a way of organising the chemical elements by reactivity and characteristics. The patterns relate to the number of protons and electrons in each atom, and as a result the properties of undiscovered elements can be predicted fairly precisely. It is organised in chronological order of atomic number.
Each period relates to the number of shells of electrons, and each group relates to the number of outer shell electrons.

1.14 deduce the electronic configurations of the first 20 elements from their
positions in the Periodic Table

The first two elements are hydrogen and helium, which have 1 outer shell, with electronic configurations 1 and 2 respectively.
The second period contains 8 elements, with (left to right) electronic configurations
2,1 , 2,2 , 2,3 , 2,4 , 2,5 , 2,6 , 2,7 , 2,8
The third period resembles the second:
2,8,1 , 2,8,2 , 2,8,3 , 2,8,4 , 2,8,5 , 2,8,6 , 2,8,7 , 2,8,8
and so on.

1.15 deduce the number of outer electrons in a main group element from its
position in the Periodic Table.

The 8 groups of the periodic table tell us how many outer shell electrons the elements of the group have.
Group 1 : 1 valence electron
Group 2 : 2 valence electrons
etc.
etc.
Group 0 : full outer shell, so 2 or 8 valence electrons.

Section 1 b) Summary

An atom is the smallest existing chemical particle with an equal number of protons and electrons, and as a result has no charge. Each atom is a chemical element, which can react with each other to form compounds or physically combine to make a mixture. 

A compound is a substance formed by the chemical union of two or more chemical elements, with a definite, unchanging ratio. It has its own properties, different from the properties of its parts, and requires chemical reactions to be separated. 

A mixture is made from different substances that are not chemically bonded. Each of the substances within a mixture retains its own properties, and the ratio is not fixed. The substances are easily physically separated. 

Methods of separation include:

Filtration: Separating insoluble particles from a liquid

Passing a mixture through a filter funnel.

Evaporation: Removing liquid from a solution

Heating a solution to boiling point until the liquid is gone.

Chromatography: Separating controlled substances or dyes

Placing dots on chromatography paper and letting it run up the paper with capillary action.

Distillation: Separating liquids from each other. Simple - two liquids. Fractional - many liquids, involving a fractionating column.

Boiling and condensing liquids of different boiling temperatures. 

Chemical particles disperse through a fluid through diffusion and dilution. Diffusion is the net movement of particles from an area of high concentration to an area of low concentration. 

This can be demonstrated using experiments between hydrochloric acid  and ammonia, or bromine in a glass cylinder, as well as by placing food dye in water. The dispersal of particles can be seen through the experiments described here (specification)

Section 1 b) Key Words

Atom: The smallest particle of a chemical element that can exist.

Chromatography: The separation of different particles of a solution e.g. pigments in ink, by placing them on paper and allowing a solvent to transport the particles up the paper to different distances through capillary action.

Compound: Two or more chemically bonded elements. They can be ionic or covalent.

Crystallisation: The formation of crystals through evaporation

Diffusion: The net movement of particles from an area of high concentration to an area of low concentration.

Dilution: Making a substance weaker (e.g. HCl can be diluted so it is less corrosive, food dye disperses through a liquid and becomes weaker) through the addition of other substances.

Element: A substance found on the periodic table that cannot chemically be split up into simpler substances. Its atoms have equal numbers of electrons and protons, resulting in balanced charge.

Evaporation: The state change of liquid to vapor, used to separate a solid from a liquid solution.

Filtration: Separation using a funnel and filter paper to remove large, insoluble particles.

Fractional distillation: Heating a mixture of liquids into a fractionating column to separate them into fractions which differ in boiling point. The gases then pass through a a tube where they are condensed and collected as a liquid again.

Magnetic separation: Separation of magnetic and non-magnetic substances, used industrially in recycling plants, etc.

Mixture: Two or more compounds or elements that are physically mixed but not chemically bonded, e.g. air or steel.

Molecule: A group of atoms bonded together in the simplest form of a chemical compound that can take part in a chemical reaction.

Separation: Techniques of removing different parts of a mixture from each other to obtain substances combined within it.

Sieving: Removing larger insoluble particles from smaller insoluble particles by passing it through a sieve. Different sized holes in sieves can be used for different purposes

Simple distillation: Separating a mixture of liquids through heating, then condensing the vapor and collecting the purer substance Works best with mixtures containing few different chemicals (e.g. separating ethanol and water)

Section 1 b) Specification

1.4 describe and explain experiments to investigate the small size of particles
and their movement including:
i dilution of coloured solutions
ii diffusion experiments

Experiment 1: Dilution
Add a coloured substance to a solvent, e.g. food dye to a solvent, e.g. water. Over time, the intensity of the colour will decrease as it spreads throughout the liquid and dilutes- the concentration of the food dye decreases. Dilution increases at higher temperatures due to increased kinetic energy of particles, so applying heat decreases the time it takes for the dye to become fully diluted.

Experiment 2: Diffusion
Using a glass tube, place cotton wool soaked in ammonia solution at one side of the tube, and cotton wool soaked in hydrochloric acid at the other end. Both ends should be sealed with bungs. After a few minutes, a white ring of ammonium chloride will form in the tube, closer to the hydrochloric acid end. This tells us that the particles have diffused away from their respective ends to collide and react. The ammonia particles are smaller than the hydrogen chloride particles, and therefore move faster which is why the ring forms closer to the hydrochloric acid.

Experiment 3: Diffusion
Place liquid bromine at the bottom of a glass jar, and another empty jar upside down on top of it. As the bromine begins to evaporate, you can observe the volume of liquid decreasing, and the gas in the jar changing colour as the darker-coloured bromine particles diffuse upwards.

1.5 understand the terms atom and molecule

An atom is the smallest particle of an element that can exist. It has balanced charge (the same number of positively charged protons and negatively charged electrons) and a mass relative to carbon (12), made up of the neutrons and protons, each with mass of 1.
A molecule is a group of atoms bonded together, the smallest unit of a chemical compound that can take part in a chemical reaction, e.g. H2O

1.6 understand the differences between elements, compounds and mixtures

An element is one type of atom found on the periodic table, sometimes found bonded to another atom of the same element, e.g. O2, but it is always pure.
A compound is two or more elements chemically bonded in fixed proportions to form a new molecule, e.g. CO2
A mixture is two or more compounds or elements that are not chemically bonded, e.g. air, or a metal alloy such as steel.

1.7 describe experimental techniques for the separation of mixtures, including
simple distillation, fractional distillation, filtration, crystallisation and paper
chromatography

Solutions can be separated using a number of different techniques based on the physical differences of the substance (e.g. soluble and insoluble compounds). These include distillation, decanting, sieving, filtration, chromatography, crystallisation and magnetic separation.

Simple distillation: A liquid is boiled in a distilling flask, and the vapor travels through a tube, where thermal energy is passed to the cool water outside it and the vapor condenses into a liquid. The purified liquid then trickles out into a beaker. This generally is used to separate two liquids in a mixture, with different boiling points (e.g. ethanol and water)

Fractional distillation: The apparatus is similar to simple distillation, but the addition of a fractionating column filled with glass or plastic beads that allows better separation between the fractions due to condensation and re-evaporation occurring on the surface of each bead (distilling the mixture repeatedly). This allows the separation of more complex mixtures of liquids.
More on distillation

Filtration: A mixture is passed through a funnel with filter paper in it. The insoluble solid is left on the filter funnel, while the solution passes through the paper as the particles are small enough to fit through the gaps in the paper. This is used to separated a solution and insoluble particles.

Evaporation: A solution is heated to evaporate the liquid (e.g. water) leaving behind a solid that was previously dissolved. This is used to retrieve soluble compounds from solutions.

Crystallisation: A solution (e.g. aqueous sodium chloride) is heated to its boiling point, allowing the liquid, in this case the water, to partially evaporate. The solution is then left over a period of time, often several days to allow further water to evaporate at a lower temperature, causing crystals to form.

Chromatography: Different pigments in a mixture can be separated using chromatography. Dots of dye are placed at regularly spaced intervals at the bottom of a piece of chromatography paper, and the paper is placed in a beaker of solvent (the solvent should not reach the dye so it isn't dissolved and dissipated into the solution). The solvent will travel up the paper, and dissolve the pigments. Heavier pigments will be carried a shorter distance than pigments with smaller particles.

1.8 explain how information from chromatograms can be used to identify the
composition of a mixture. 

Using a chromatogram, the composition of a mixture of dyes can be determined through comparison of different pigments. Different pigments are more or less water-soluble, and have different particle sizes, resulting in the pigments travelling a certain distance up the paper. By comparing a mixture of pigments, and marking the distance they travel, then comparing with individual pigments and the distance they travel, the composition can be determined. Pigments of the same kind will travel the same or similar distances.