AQA unit 1 AS Chemistry notes

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sodium, potassium, silver, H, ammonia, copper 1 +
Magnesium, calcium, iron 2, zinc, lead 2, copper 2, nickel 2 +
Aluminum, chromium 3, iron 3 +
Chemical charges
Isotope signatures: isotope found in space
Relative atomic mass: the average mass of an atom compared to a twelfth the mass of carbon 12.
Relative molecular mass: the average mass of a molecule compared to a twelfth the mass of carbon
Ion: an atom in which one or more electron has been removed producing a positively charge ion, or one
or more electrons have been added to give negatively charged ions.
Relative atomic or molecular mass of element formula:
(Mass number x percentage abundance) + (Mass number x percentage abundance) + (Mass number x percentage abundance)
Subshells of orbitals with their max electron possession:
2 6 10 14
Electron configurations follow this rule e.g. 1S2 2S2 for Helium-2
Spin boxes(electrons do not like to be paired) e.g. oxygen-8:
Ions are displayed in the same manner, always display states of substances
EXCEPTIONS: Copper and chromium are special because they end with 4S1 3D9 and electrons are
removed starting with the first letter eg. Miss out 4S and do only 3D9.
Hunds rule: electrons organise themselves so that as far as possible they main unpaired occupying the
maximum number of sub-level orbitals as possible.
Mass spectrum: shows isotope mass number and isotope relative abundance
Ionisation energy: the energy charge when one mole of gaseous atoms forms one mole of gaseous
ions with a single positive charge, depending on charge there's first, second etc.
Increasing in periods:
Increasing protons
Increasing ionisation energy
Increasing nuclear charge
Electrons are closer and atomic radii decreases
Increasing in groups:
Increasing shells, more distance from nucleus, less attraction

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Decreasing ionisation energy
Decreasing nuclear charge
Increasing atomic radii
EXCEPTIONS: group 2-3 and 5-6 because repulsion occurs and electrons are easy to remove in these
Metals that react with water to produce an alkaline solution are called alkaline earth metals
Moles: just as a pair is 2 and a trio is 3, a mole is 6.02 x 1023 representing its amount
of particles.
6.…read more

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Empirical formulae: the simplest ratio of atoms of each element present in a compound e.g. a
substance contains 0.004g of calcium, 0.006g of carbon and 0.0012g of oxygen, give the Empirical
formulae of this compound.
RMM: Ca =40, C=12, O=16(X3)=48
Ca: 0.004/40 C: 0.006 /12 O: 0.0012/48 Divide their masses by their RMM
=0.0001 =0.0005 =0.000025 (or divide percentages by masses)
0.0001/0.000025 0.0005/0.000025 0.000025/0.…read more

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Titration:practice to determine reacting
4g of NaOHcm3 is dissolved in 1dm3 of solution, calculate molarity (concentration)
Concentration=moles/volume moles=mass/RMM
4g/(23+16+1)=0.1 moles 0.1/1dm3=0.1moldm-3
n.b. 1. if the volume is in cm3, divide by 1000 to dm3
2. to get gdm concentration, multiply by RMM
Solid liquid
Liquid gas
Covalent bonding is seen when the electron needs of atoms are similar(same charge)thus share
electrons.…read more

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Linus to discern bond,the`electron pulling power'ranges from 0-4,F=4,Cs=0.7
this increases with the periods and core charge and decreases with the increasing groups and radii, causes
dipole moment :exists when there is a distance between the dipole, is shown by an arrow from + to ­,
where q is charge and R is distance and =(A) (B),measured in Debyes
Polar molecules or permanent dipoles have a net dipole moment which=0 and is non-symetrical
Permanent dipole-permanents dipole interactions: weak intermolecular forces between polar
molecules e.g.…read more

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Electrostatic forces are in-between sheets
o ionic structure are similar yet are brittle as anions and cations repel each other and splits
o simple solids are different, giant solids e.g.…read more

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In covalent bonding two atomic orbitals overlap to form a molecular orbital which can only 2 electrons
Normal covalent bond Dative covalent bond Sigma and Pi bond
Carbon promotes electrons to be able to Atoms in group 5,6,7 e.g.…read more


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