This document provides a comprehensive summary of Units 1-14 of OCR A Level Chemistry, covering key foundational topics essential for exam success:
Unit 1 - Moles, Equations, and Acids: Focuses on the mole concept, stoichiometry, and acid-base reactions. It covers calculations involving moles, c...
Definitions
relative atomic mass average weighted mass of an atom Percentage yield
actualyield
ofanelement relative to 412th the massof an atom of C 100
Relative isotopicmass average weighted mass of an
yield theoreticalyield
isotope relative to 412th the mass
of an atom of I maynotbe 100 as
relative molecularmass average weighted mass of one reversible reactions
molecule relative to 412th the mass
molecule particle consisting
of an atom of C impurities
of ormore non metal atoms
2 side reactions
bonded covalently
Relative formulamass average mass ofone formulaunit
Atomeconomy Mrofuseful
total herof1
Relativeabundance of an isotope is proportion
in a naturally occurring sample
of an isotope
the element
of 4 atom economy little waste
Mole amount ofsubstance whichcontains the Avogadro
Hydratedsalts
constantof a specified elementary particle 1 Moles anhydrous
of
Avogadroconstant number comms 2 Moles
of water
Empiricalformula wholenumberratioofatoms in a compound waters of
Molecularformula actualnumber atoms in one molecule crystallisa
of of anhydrous
a compound
Backtitrations
work backwards
Equations Moles equations watchmolar ratios
watch dilutions
and ago Acids
my gg p
At roomtemperature and pressure strong acid completely dissociate
24000cm General equations
1 Acid metal salt hydrogen
Moles ofgas volumffdmt
2 Acid metaloxide salt t water
at the same temperature 3 Acid metal hydroxide salt water
Equal volumes of gases
molecules
pressure contain the same number of 4 Acid metalcarbonate salt Hao CO2
im
, Firstionisation energy amountofenergy
required to remove one e fromeachatom
atomic number protons electrons whencharge o in one mole of gaseous atoms toformone
mass number protons neutrons mole of gaseous I ions
Isotopes atoms ofthe sameelement withthe X
samenumberofprotons but a differentnumber
Xt te
what increases ionisation
of neutrons energy
RAM xabundance RAMaxabundance d distance to nucleus
Relative isotopic mass
total abundance I shielding
mm T nuclearcharge
mom stronger attraction between highest
5 orbital energy electron and nucleus
p orbital L higher ionisation
energy
successive ionisation energies
G x
J a
orbital region in spacein which
there is a 951 probabilityoffinding Trends in ionisationenergies
a given electron
Rules for filling orbitals
Lowestenergyorbital
Atomic
I Preferto occupy an orbital structure
x
Generally increases across the periodas
d distance to nucleus
Shielding
T nuclearcharge
Generally falls down the group
T distance to nucleus
9 Shielding
d block elements
outweighs 4 nuclearcharge
Loseelectrons from 4S
rbital firstwhen forming But Be B
ons But N O
B electron in Ip subshellus Be in
2 exceptions to orbital oxygen 4th p electronpairs
25 subshell so Be vs B
filling rules up
L electron repulsion 4 lowerenergysub shell
r is252,8353ps4s 3ds
easier to removeelectron d distance to nucleus
u is252,8353ps4s 3d
I ionisation energy t shielding
outweighs d nuclearcharge
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