Chemistry Paper 1 Owen

An atom is a tiny particle made up of protons, neutrons and electrons.

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

A compound is a substance which has two or more elements that combine together.

A mixture is a made up of two or more substances that are not chemically combined together.

Filtration - separating insoluble substances from a solvent.

Crystallisation - separating a soluble solid from a solvent.

Distillation - separating a solvent from soluble solids.

This model suggested that negative electrons were embedded in a ball of positive charge.

Geiger and Marsden fired alpha particles at a very thin sheet of gold foil. They discovered that a few of the alpha particles were being repelled, showing that there must be a tiny spot of positive charge in the centre of the atom, the nuclear model was then proposed.

The nuclear model contained positively charged protons in the centre of the atom and negatively charged electrons orbiting the protons.

The atom is believed to have a nucleus, which contains protons and neutrons. It is also believed that electrons orbit the nucleus.

Protons have a positive charge.

Neutrons have no charge.

Electrons have a negative charge.

The relative atomic mass of an atom is the number of protons and neutrons it contains. Electrons have no mass so do not input to the relative atomic mass.

An ion is an atom with a charge, positive or negative, usually as a result of gaining or losing electrons.

An isotope is an atom of a certain element that has a different mass number, usually as a result of gaining or losing a neutron.

Shells

An energy level

It shows the number of electrons in each energy level.

2, 8, 8, 8 etc.

The periodic table is a table of elements arranged in order of atomic numbers and classified into groups based on electronic structure.

It was first laid out in order of atomic weight.

He proposed the idea that every 8th element, based on atomic weight, acted similarly.

He changed the order of elements so that elements with similar properties were in the same group.

Metals are found on he left hand side or in the middle of the table.

Non-metals are found in the right hand corner of the table.

The alkali metals.

They are very reactive.

They have low boiling/ melting points.

They have low densities.

The greater the number of electrons, the more reactive the alkali metal is. This is because there is a weaker electrostatic force for electrons further from the nucleus, meaning they can be released more easily when bonding.

Halogens

Quite unreactive.

Poor conductors.

Low melting/boiling points.

The reactivity of halogens decreases going down the group. This is because the shells have a weaker force of attraction going away from the nucleus. Meaning the atom will find it harder to bring electrons in.

Noble gases.

Noble gases have a full outer shell so are very unreactive.

They are the elements found centrally in the periodic table, between groups 2 and 3.

They have high melting points, compared to alkali metals.

They are much harder, stronger and more dense than alkali metals.

Solids.

Liquids.

Gases.

It describes the movement and arrangement of particles.

Solids are packed closely together in a fixed arrangement. They vibrate constantly.

Liquids are close together in a changing, random arrangement. They move very quickly.

Gas particles are very spread out in a random arrangement. They move very quickly.

It assumes that particles are solid spheres with no forces between between them.

When non-metallic elements join together by sharing electrons.

Ionic bonding is when metallic elements react with non-metallic elements. The metal atoms lose electrons and form positive ions whilst the non-metal atoms gain electrons and become negative.

When lots of oppositely charged ions are held together by strong forces of attraction, which act in all directions. It can also be called a giant lattice

Giant ionic structures are very strong and require a lot of energy to break down, this is why they have high melting and boiling points.

When they melt, they have free flowing electrons meaning it can conduct electricity.

Intermolecular forces are forces of attraction between molecules.

Polymers are long chains of small molecules that covalently bond to each other. They have very large molecules and are solids at room temperature. They have strong intermolecular forces and the simple molecules don't conduct electricity.

They are formed when every atom in the structure is joined to other atoms by strong covalent bonds.

Diamond is a carbon based giant covalent structure. Every carbon atom forms stroganoff covalent bonds with 4 other carbon atoms. It does not conduct electricity.

Graphite is a carbon based giant covalent structure. Each carbon atom bonds with three other atoms. They form hexagonal rings which are arranged in giant layers. There are only weak intermolecular forces between the layers so they easily slide off of each other. Graphite can conduct electricity.

Graphite can conduct electricity because every atom has a delocalised electron which can carry a charge and move through the structure.

Graphene is a single layer of graphite and is one atom thick. It can conduct electricity excellently.

They are arranged regularly.

Because when they bond, he electrons in the outermost she'll become delocalised and can carry charges throughout the structure.

A fullerene is a carbon based giant covalent structure which joins together to make large hollow shapes. The structure of them is based on rings, pentagonal, hexagonal or heptagonal.

They have a high tensile strength, making them useful to reinforce composite materials.

They have delocalised electrons so can conduct electricity.

An alloy is a mixture of metals or metals with other elements. They are very strong because the atoms are irregularly sized atoms so the layers find it more difficult to slide off if each other.

1x10^-10

A nanoparticle is a particle that measures between 1 and 100 nanometres. 1 nanometre is 1x10^-9 metres.

They are used in cosmetics because they can be absorbed deeply into the skin.

They can be used in medicine to deliver drugs into the body.

They can be used in computers, nanowires give vastly improved memory capacities and speeds.

One mole of a substance is the relative atomic mass or relative formula mass of that substance expressed in grams.

6.02x10^23 atoms per mole

Number of moles = mass / relative formula mass

They tell you the number of moles of substances involved in a chemical reactions.

The percentage yield of a chemical reaction describes how much product is made.

Percentage yield = mass of products / maximum possible mass of products x 100

It allows industries to help conserve resources and reduce waste.

The atom economy is a measure of the amount of starting materials that end up as desired products.

Atom economy = relative formula mass of the desired product from equation / sum of relative formula masses of the reactants from the equation x 100

Because reactions with a high atom economy are more sustainable as they use fewer natural resources and give fewer waste products.

G/dm^3 (grams per decimeter cubed) or mol (moles)/dm^3

Mass (g) / volume (dm^3)

Finding the exact volumes of acids and alkalis that react with each other.

Measure a known volume of alkaline and put it in a conical flask.

Add a few drops of indicator into the alkali.

Fill a burette with acid and record the initial reading on it.

Add a small amount of acid into the flask and mix the solution.

Repeat that until the indicator signifies that the solution is neutral.

Record the final reading on the burette so that you have worked out the volume needed to neutralise the alkali.

Repeat the experiment.

Use the mass of the solute divided by the volume of the solute.

Volume of gas (dm^3) / 24 (dm^3)

The loss of electrons.

Gain of electrons.

A table of elements that are ordered in order of their reactivity.

Hydrogen.

A reaction in which a more reactive metal displaces a less reactive metal from the aqueous solution of one of its salts.

By chemical reactions.

Heating with carbon.

Electrolysis.

They produce a salt and hydrogen gas.

Hydrochloric acid => chloride (Cl- ions)

Sulfuric acid => sulfates (SO42- ions)

Nitric acid => nitrates (NO3-ions)

The ionic equation that occurs to each reactant.

Salt + hydrogen

Salt + water

Salt + water

salt + water + carbon dioxide