Chemistry

Ionic bonding is the chemical link between two atoms caused by the electrostatic force between oppositely-charged ions in an ionic compound. 

This happens between a non-metal and a metal for example Chlorine and Lithium and it is where one of the elements give up electrons.

When the element has given up or donated their electron(s) they become an Ion. An Ion is a element that is postivatly or negativly charged depending on how many Electrons and Protons they have.

A Covalent bond is where the elements/atoms share electrons with another Atom this only occurs with non-metals for example a Oxygen to Oxygen double bond this is a covalent bond.

These bonds are very strong and require alot of energy to break and give out a high amount of energy when these bonds are made!

In Covalent bonds you can have Dative pairs this is where one Atom gives up two more electrons to the other Atom.

How to work out moles:

Moles= Mass of substance/Molecular mass

How to work out Concentration:

Concentration=Moles/Litres

How to work out percentage error:

Percentage error= (Error*how many times it was done/average)*100

How to work out moles in solutions:

Moles dissolved= Volume (cm3)/1000cm3*concentration (moles dm-3)

In the context of chemistry and the periodic table, periodicity refers to trends or recurring variations in element properties with increasing atomic number. Periodicity is caused by regular and predictable variations in element atomic structure.

When going across groups the melting point drops!

Also when going across the group the size of the atom decreases, but when you go up the period the atom sizes also decreases.

The first ionisation enthalpy is the taking of ther electron from the shell furthest away from the nucleus.

The second ionisation enthalpy requires more energy to take the electron due to their being less sheilding and it being a posotive atom meaning the electrons will have a higher attraction to the nucleus.

The third is even higher for the same reasons.