Principles of Chemistry

Melting

Boiling

Condensing

Freezing

Subliming

Strong forces of attraction between particles which holds them close together in fixed positions to form a very regular lattice structure
Definite shape
Definite volume
Particles vibrate about a fixed position
The hotter they become, the more the particles vibrate causing solids to expand slightly when heated

Weak force of attraction between particles
Particles randomly arranged and free to move past each other
Definite volume
Don't keep definite shape and will flow to fill a container
Particles constantly moving with random motion
The hotter they become, the faster the particles move causing liquids to expand slightly when heated

Very weak force of attraction between particles
Particles are free to move and are far apart
Particles travel in straight lines
Don't keep a definite volume
Don't keep a definite shape
Will always fill a container
Particles move constantly with random motion
The hotter they become, the faster the particles move causing gases to expand when heated or their pressure increases

The movement of particles from an area of high concentration to an area of low concentration

Atoms are the smallest part of an element which still maintain all the properties of an element

An element contains only one type of atom

A compound contains two or more elements chemically bonded together

A mixture contains two or more elements and/or compounds that are not chemically bonded together
Not a pure substance

Heavy (relative mass of 1)
Positively charged (relative charge of +1)
Found in nucleus

Hardly any mass (relative mass of 1/2000)
Negatively charged (relative charge of -1)
Move around nucleus in energy levels called shells

Heavy (relative mass of 1)
Neutral (relative charge of 0)
Found in nucleus

Middle of the atom
Contains protons and neutrons
Positively charged (because of protons)
Almost whole mass of the atom is concentrated into the nucleus

Because neutral atoms have no overall charge

Bottom number
The number of protons or electrons

Top number
The number of protons and neutrons

Neutral particles made up of two or more atoms bonded together

A substance in which other substances dissolve into to form a solution

A substance that dissolves in a solvent to produce a solution

A mixture of one or more solutes dissolved in a solvent

A solution in which the maximum amount of solute has been dissolved so no more solute will dissolve into the solution

Place two pieces of cotton wool at either end of a glass tube, one soaked in hydrochloric acid and the other soaked in aqueous ammonia
A white ring of ammonium chloride will form as they diffuse towards each other and react
The ring forms closer to the hydrochloric acid because the ammonia particles are smaller and lighter than the hydrogen chloride gas so they diffuse more quickly through the air

Fill half a glass with bromine vapour and when the cover slip seperating the two ends of the glass is removed, the brown gas diffuses to fill the whole glass

Used to seperate an insoluble solid from a solution as the insoluble solid particles are too large to fit through the holes of the filter paper

Used to seperate a soluble substance from a solvent
The solvent is evaporated until there is too little for the substance

Used to seperate two liquids or a soluble substance from a solvent
It is heated and the substance with the lowest boiling point turns into a vapour which travels up the column before turning back into a liquid in the cold condenser and being collected at the end
The mixture should not be heated above the boiling point of the second substance

Used to seperate a mixture of liquids with different boiling points
Using a fractionating column
Liquids with lowest boiling points evaporate first

Used to seperate coloured substances
Substances dissolve in the solvent as it moves up the paper
Most soluble substance will travel furthest

The base line should be drawn in pencil as ink would move with the substances
The level of the solvent should be below the base line or the substances will dissolve in the solvent and not move

distance moved by solute (spot)/ distance moved by solvent

Retention factor
How well the colour stays on the paper in the solvent

Different atomic forms of the same element, which have the same number of protons but different numbers of neutrons
Isotopes of the same element have identical chemical properties because they have the same electronic configuration
Isotopes of the same element have different mass numbers but the same atomic number
Isotopes of the same element have slightly different physical properties (e.g. density, bpts, mpts)

Multiply the mass of each isotope by its relative abundance (%)
Add those together
Divide by the sum of the relative abundances (%)

Arranged in order of increasing atomic number
Arranged in groups (vertical columns) and periods (horizontal rows)

Created by Dmitri Mendeleev in 1869

The elements in a group all have the same number of electrons in their outer shell
All have similar properties

The elements in a period all have the same number of electron shells

Left-hand side of the periodic table
Conduct electricity because they allow charge to pass through them easily
Metal oxides are alkaline so they will neutralise acids
They lose electrons to gain a full outer shell

Right-hand side of the periodic table
Poor conductors of electricity
Non-metal oxides are acidic
They gain electrons to gain a full outer shell

All inert meaning that they don't react
They have full outer electrons shells and are therefore stable

Is the loss of electrons

Is the gain of electrons

When metals react with non-metals, electrons are lost by the metal and gained by the non-metal so that both have full outer shells and are stable
They become ions and form an ionic compound
The metal atoms become positive ions and the non-metal atoms become negative ions

Ag+

Cu2+

Fe2+

Fe3+

Pb2+

Zn2+

H+

OH-

NH4 +

CO3 2-

NO3 -

SO4 2-

Positively charged metal ions and negatively charged non-metal ions are attracted to each other and are held together by strong electrostatic forces of attraction
They form a giant 3D crystal lattice structure held together by many strong ionic bonds

High melting and boiling points
Very brittle
Solid substances do not conduct electricity but molten and aqueous substances do

Electrostatic forces of attraction are very strong between oppositely charged ions and many of these bonds need to be broken before ionic substances can melt

When a force is applied to an ionic substance, the lattice structure shifts so that ions of the same charge are next to each other and they repel so the lattice breaks.

Solid substances don't conduct electricity because as the ions are in a lattice structure they cannot move so charge cannot be carried through the structure, whereas, ions in aqueous or molten substances can move around so they can carry charge through the substance and can conduct electricity

A covalent bond forms when non-metal atoms share pairs of electrons to gain full outer shells of electrons

Because, even though the covalent bonds within the molecules are very strong, there are weak intermolecular forces of attraction between the molecules so they can easily be overcome

Because intermolecular forces are created by the movement of electrons, therefore, the more electrons, the greater the intermolecular forces of attraction resulting in higher melting and boiling points

They do not conduct electricity because they are made up of molecules and molecules are not electrically charged, they are neutral

They contain many atoms, each joined to adjacent atoms by strong covalent bonds. The atoms are arranged into giant regular lattices that are extremely strong because of the many bonds involved. Therefore they have high mtpts and bpts because of the many trong covalent bonds that need to be broken

Most covalent substances do not conduct electricity because they have no free (delocalised) electrons to carry charge through the structure

Giant covalent structure
Allotrope of carbon
Each C atom forms 4 covalent bonds
Very high melting and boiling points (because many strong covalent bonds need to be broken in order to seperate the atoms)
Does not conduct electricity as it has no delocalised electrons
Very hard and strong and durable because of the rigid lattice structure

Allotrope of carbon
Giant covalent structure
Each C atom forms 3 covalent bonds
Very high melting and boiling points (because many strong covalent bonds need to be broken in order to seperate the atoms)
Only three out of four of carbon's outer shell electrons is used so each carbon atom has a delocalised electron that can carry charge so graphite conducts electricity
Soft and brittle because graphite is formed of layers of carbon atoms (because only 3 of the outer shell electrons are bonded) which are held together by weak intermolecular forces so the layers can slide over each other making graphite soft and brittle

Simple molecular structure
Allotrope of carbon
Each C atom forms 3 covalent bonds
Not very high melting and boiling points (because only needs to overcome relatively weak intermolecular forces between molecules as no covalent bonds are broken)
Has one delocalised electron but it cannot move between molecules so it is a poor conductor of electricity
Soft because molecules are only held together by intermolecular forces and so they can slide over each other

Occurs between atoms of metal elements
When two metals bond, the extra electrons on the outer shell leave the atom. These electrons become delocalised and there is a stong attraction between the positive nucleus of the atoms and the cloud of delocalised electrons.

An alloy is a mixture of two or more metals that combine the properties of the different metals that make them up. Another type of atom is introduced into the metallic structure, jumbling up the atoms

High mtpts and bpts because the electrostatic attraction between the nucleus and the sea of delocalised electrons is very strong and requires a lot of heat to overcome

They are good conductors because they have delocalised electrons that can carry the charge through the structure

Metals are malleable because the atoms are arranged in regular rows and can easily slide over each other