Chemistry basics - Atoms ,electrons for any level

hope this helps this is combonation of some gcse stuff and and starting AS work

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The atom - what it is- GCSE level

An atom is the smallest uncharged particule of an element it is split in to three sub atomic parts

protons- have a +1 charge and are positive 

neutrons have no charge 

electrons have -1 charge and are negative 

BECAUSE AND ATOM IS NOT CHARGED IT HAS EQUAL NUMBERS OF PROTONS AND ELECTRONS THE ATOMIC NUMBER WILL TELL YOU HOW MANY OF EACH THERE ARE.

to find out how many neutrons there are you must take away the atomic number from the relative atomic mass. the relative atomic mass will tell you the weight of the protons and neutrons 

both protons and neutrons have a weight of 1 (for agruements sake we do not know their real mass but this is the excepted term for their weight ) electrons 1/1836

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isotopes - GCSE and AS level

this when an atom has more neutrons than normal , this does not effect the reactions that this element has with other elements nor the charge or the element it just means that it is a heavier atom for example:

you can have chorine 35 ( rounded) and 37( rounded) they are just natural variations of an atom some isotopes can be radioactive like carbon 14

there can be a number of istopes for each element

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IONs- GCSE

ions are atoms which are charged they have either lost or gained electrons 

for example a lithium atom has three electrons , 2 in the inner shell , one on its outer shell 

an atoms aim in life is to have a full outer shell of electrons so what is it easier for lithium to do lose one or gain 7 ? A: lose 1 after lithium loses this one electron it has a +1 charge and a full outer shell with 2 electrons on ( all other shells other than the first one nearst the nucleus have 8) lithium has gained this +1 charge because it has lost 1 electron which has a negative charge therefore becuase it has lost a negative it is becoming more positive by the number of electrons it has lost which is 1

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a few random bits

the mass of an atom is focused in the centre - the neucleus but most of the atoms volume comes from the space inbetween the shells of electrons 

in terms of size the neucleus would would be a pea in the centre of a football stadium if the outer shells went all the way round the stadium ! so it is very dense

remember that the reactivetity of an atom depends on the number of shells and how far away they are form the positive neucleus and if they have to gain electrons or lose them .

if they have to gain electrons it is easier if they have fewshells so the pull from the neculeus is stronger than if there are many shells it is harder to gain them as they are not near enough to the neucleus to pull an electron off another atom 

if they have to lose it is better that they have more shells as it makes the electron easier to lose as it is not having to fight the pull of the neucleus as much 

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