Chemistry unit 4

A charged particle

When an atom gains or loses an electron to achieve a full outer shell and be more stable.

It requires less energy to achieve a full outer shell.

It takes a lot more energy to lose or gain 3,4 and 5 electrons compared to losing or gaining 1 or 2.

The electron is on the right hand side, e.g.

Na → Na(+) + e(-)

The electron is on the left hand side, e.g.

Cl + e(-) → Cl(-)

Group 1,2,6 and 7, because they only need to gain or lose a small amount of electrons so less energy is required.

Ionic and covalent

Electrostatic forces

High mpt and bpt

Conduct electricity when melted or dissolved in water (molten or aqueous form)

OH(-)

SO4(2-)

NO3(-)

CO3(2-)

NH4(+)

A regular 3D structure

The ions are free to move and carry charge

The ionic bonds are very strong so a high amount of energy is required to break the bonds.

Neutral charge

the actual number of atoms of each element present in a compound or molecule.

e.g. C6H12O6

The simplest, whole number ratio of atoms to each element in a compound. It doesn’t tell you the exact amount of atoms there are, just the ratio of the atoms of each element.

Find the simplest whole number ratio of atoms in the compound.

Small atoms that are joined by strong covalent bonds, but between the individual molecules are only weak intermolecular forces that can be easily broken.

e.g. Water or methane

Billions or trillions of atoms arranged in a regular lattice joined by strong covalent bonds.

Non-metal + non-metal

The intermolecular forces (between the molecules) only require a small amount of energy to break

Low mpt and bot - weak IMF

Don’t conduct electricity

Huge numbers on non metal atoms joined by covalent bonds

Very strong

High mpt and bpt - have to break strong covalent bonds to melt

Don’t conduct electricity because they don’t contain charged particles - except graphite

Small molecules made up just a few covalently bonded atoms, whilst the molecules are joined by weak IMF.

All of the atoms are covalently bonded in regular repeated lattices which makes them stronger with higher mpt and bpt.

Different structural forms of the same element in the same physical state.

Giant covalent structures, which means they’re both made up of regular lattices of covalently bonded atoms and are very strong.

Each carbon atom is covalently bonded to 4 other carbon atoms so it forms a regular 3D pattern.

Strong

High mpt

Doesn’t conduct electricity - no free electrons or ions to move around

Each carbon atom is only bonded to 3 other carbon atoms

The atoms are arranged into hexagons which form flat sheets that become layers

They’re held together weakly as there’s no covalent bonds between them. This means they’re free to slide over each other

Soft

High mpt

Can conduct electricity and heat- each carbon atom has 1 delocalised electron that’s free to move around.

Graphene.

Strong

Can conduct electricity

Tubes and spheres - called fullerenes

Scientists can form spheres around other molecules like drugs, so it acts like. cage and can deliver the drug to parts of the body.

Also used as an industrial catalyst bc it has a large SA:V ratio

Can be used in nanotechnology

A hollow sphere (C60)

Allotropes of carbon with hollow shapes like spheres or tubes used in medicine, batteries etc.

Bonding between two metals

Metals are a giant structure of atoms arranged in a regular pattern, all the electrons are shared between the atoms in the metal so there’s lots of delegalised e-. Electrostatic forces of attraction holds everything together.

High mpt and bpt

Conduct electricity

Malleable - bent into shapes without breaking

A metal combined with one or more other elements.

The regular structure is disrupted so the layers can’t slide over each other, so the alloys are much harder than the pure metals.

Each metal atom becomes an ion with a positive charge, by giving up its outer shell e-. The e- become delocalised and shared across all the ions in the structure.

Steel

• Strong forces of attraction

• Forces hold them close together, (fixed position

• Keeps a definite shape and volume

• Particles vibrate in place

The particles gain more energy and vibrate more, which weakens the forces and at the melting point it becomes a liquid.

• Weak forces of attraction

• Free to move particles

• Definite volume

• Shape can change

• Flows to fit a container

The [articles gain more energy and move around faster, which weakens the forces until it reaches the boiling point where the bonds are broken and it evaporates into a gas.

• Forces of attraction are very weak so they’re basically free to move.

• Constantly moving in any direction

• Don’t keep a definite shape or volume, always fill a container.

Gas to liquid

Liquid to solid.

It isn’t perfect, particles aren’t actually solid, spheres or inelastic. They’re atoms or ions or molecules.

It doesn't include details of the forces between the particles.

That particles are small, inelastic and spheres.

Really tiny particles that can’t be seen, even with a light microscope.

Very large surface area:volume ratio, which gives it a lot of uses.

Catalysts

Nanomedicine

Nanoparticles in electrical circuits

Antibacterial purposes in medicine

They’re quite new so we aren’t sure of the effects on our bodies.

Nanoparticles help make sunscreen more effective but we aren’t sure if the particles can get into our body.

1nm-100nm