The nucleus is present in the centre of an atom
sub atomic particle
A nuetron has a mass of 1 and no charge
different versions of atoms
Atoms that have the same number of protons but a different number of nuetrons is called an isotope
The maximum amout of electrons in each shell has a pattern of 2, 8, 8, 18
The electronic configuration in the number of electrons in each shell.
E.G. Potassium has the configuraton 2,8,8,1
The stability of an atom is based on the amount of electrons on the outer shell
Periods and Groups
Groups go along the top and are the amount of electrons on the outer shell
Period go down and are the number of electron shells
tried organising the periodic table into laws of octaves
was Russian. he swapped the order of some elements to ensure their properties fitted with others in the same group.
Mendeleev left gaps for elements that had yet to be discovered, and could subsequestly estimate they're properties
His version of the Periodic table became popular because new elements were discovered and they fitted in the gaps he'd left
A few years after the Periodic Table was published, Gallium was discovered, but had been predicted my Mendeleev in his table
Properties of Metals
High melting point
Group 8 Elements are Noble Gasses, they are very unreactive and decrease in reactivity as you go down the group as they have full outer shells
Group 1 elements are Alakli metals and increase in reativity as you go down the group because they have more shells. they must be stored under oil because they react quickly with the air.
When Lithium is placed in water it fizzes and moves aound quickly
Sodium fizzes and moves more
Potassium has a purple flame and fizes and moves more.
Rubidium has a little explosion
Cesium makes a big explosion
You tell that the solution left after a Group 1 element has reacted with water is alkaline if the universal indicatior turns purple.
Elements in group 7 are hallogens. Flourine is the most reactive element of group 7. As you go down the group, the boiling and melting point increases. Bromine is a liquid at room temperature.