Chemistry

Particle     Position    Charge   Mass

Protons     Nucleus       +1           1

Neutrons   Nucleus        0            1

Electrons   Shells          -1        1/1840

The Atomic mass:

•  is the Number of Protons and Neutrons.

The Atomic Number:

• increases by 1 in the periodic table as it goes across. 
• is the number of Protons
• same as the number of electrons in an atom.     

In each shell there has to be a certain number of atoms. In the first shell, there can only be 2, in the second, there can be 8 and also in the third. 

The number of electrons in the last shell, is always the group number on the periodic table. 

The number of shells tells you which period (row) the element is in.

You work out the number of Protons, as it is the same as the atomic number and the Neutrons you take the atomic number away from the atomic mass and the Electrons is the same as the number of Protons.

A Compound is 2 or more elements bonded together.

A Mixture is 2 or more elements but they arent bonded together.

A Molecule is 2 or more atoms bonded together.

O2 is a molecule as it is only 1 atom but they are bonded together.

All elements in Group 0 all have a full outer shell. 

Atoms with incomplete outer shells can react with other atoms to achieve a full outer shell, in 3 ways all resulting in a type of chemical bond.

A Formula tells you:

• which elements are in it
• and how many atoms of that element are in it and which are bonded together

MgSO4 has Magnesium, 1 atom, Sulphur, also 1 atom and Oxygen which has 4 atoms. 

KOH, has 1 atom of all the elements but they are Potassium, Oxygen and Hydrogen.