AQA AS Chemistry notes (Unit 1).

Pretty much a condensed version of the Nelson Thornes text book. I went through the book and picked out all the important parts of the book, and left all the unnecessary bits. Some of the bits in the text book are extremely vague and don't go into enough detail, so I have used parts of the CGP Complete revision and practice guide. These notes are intended for revision, so they require you to have a back ground knowledge of the topics already. Hope they are helpful, let me know what you think :D

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Mass number, atomic number and isotopes
Proton number: The number of protons in the nucleus of an atom, the same as the atomic number.
Mass number and atomic number:
The atomic number is the number of protons. As the number of protons is the same as the number of
electrons in a neutral atom, the atomic number also represents the number of electrons.
The mass number is the total number of protons plus neutrons.…read more

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Mass spectra of elements:
The mass spectrometer can be used to identify different isotopes that make up an element.
It detects individual ions, so different isotopes are detected separately as they have different masses.
Low resolution mass spectrometry:
From the diagram above, the mass spectrum of neon has produced two peaks. One at 20 and
another at 22.
The relative abundance shown by 20 is 90% and 22 shows a relative abundance of 10%.…read more

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Energy levels:
Electrons in different shells have differing amount of energy.
These can be represented on an energy level diagram.
Shells are called main energy levels.
The first level only has a sublevel of s. The other sublevels used are p, d and f.
Atomic orbitals:
An electron is no longer considered to be a particle, but a cloud of negative charge.
An electron fills a volume in space. This is called its atomic orbital.…read more

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These shapes represent a volume of space in which there is a 95% probability of finding an
Any single atomic orbital can hold a maximum of two electrons.
Porbitals can hold up to two electrons each, but always come in groups of three of the
same energy level. This gives a total of six electrons in a p sublevel.
Dorbitals can hold two electrons each but come in groups of five. This gives a total of 10
electrons in a d sublevel.…read more

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Electron arrangements and ionisation energy.
Ionisation energy: the energy required to remove a mole of electrons from one mole of atoms in
the gaseous state.
Ionisation energy:
Electrons can be removed from atoms by hitting the atoms with a beam of electrons.
The energy it takes to do this is called the ionisation energy.
This is because as the electrons are removed the atoms become positive ions.…read more

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It is very very helpful covers almost everything love it!! love this website <3


really helpfult thank you :)

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