Nucleon number/Mass number: total number of protons and neutrons
Subatomic particles
Relative mass
Relative charge
p
1
+1
n
1
0
e
1/1836
-1
Isotope: atoms (of the same element) which have the same number of protons, but different
number of neutrons.
(isotopes have similar chemical properties: because same number of electrons/electronic
structure)
Relative isotopic mass: mass of an isotope relative to 1/12 mass of C-12
Relative atomic mass: average mass of atom relative to 1/12 mass of C-12
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Relative molecular/Formula mass: mass of a molecule relative to 1/12 mass of C-12
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Mole: the amount of substance containing 6.02x10^23 particles of that substance
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First ionisation energy : the energy needed to remove one electron from each atom of one mol
gaseous atoms
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Structure of metal: regular lattice of positive ions surrounded by delocalised electrons
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Electronegativity: ability of an atom to attract electron in a covalent bond
Polarity of a bond: electron distribution is asymmetric/two bonded atoms are partially charged
Ideal gas assumptions: there are no intermolecular forces between ideal gas molecules
ideal gas molecules have no volume
collisions between ideal gas molecules are elastic
(highT,low P) reducing T, reduces kinetic energy, so intermolecular
forces of attraction become more significant
Increasing Pressure, decrease volume and particles are
closer, so volume of particles become more significant
Standard enthalpy change of reaction: the enthalpy change when amounts of reactants as
shown in a chemical equation react together to give products under standard conditions.
Standard enthalpy change of formation: the enthalpy change when 1 mol of compound is
formed from its element in their standard states under standard conditions.
Standard
enthalpy change of combustion: the enthalpy change when 1 mol of substance is
completely burnt in oxygen (burnt in excess oxygen) under standard conditions.
Standard enthalpy change of atomisation: the enthalpy change when 1 mol of gaseous atoms
is produced from the element in its standard state under standard conditions.
Bond enthalpy/energy: energy needed to break one/a mole covalent bonds in the gaseous state
Hess's law: the total enthalpy change of a reaction is independent of reaction route taken
Oxidising agent : a species gains electron
Catalyst : a substance added to speed up a chemical reaction, remain chemically unchanged.
How catalyst speed up reaction: catalyst provides an alternative reaction route with a lower
activation energy
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Heterogeneous catalyst: catalyst is in different state to the reactants
Homogeneous catalyst: catalyst is in the same state as the reactants
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Activation energy: The minimum energy required in order for the reaction to take place.
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Le Chatelier's principle: If the conditions of a system in equilibrium changed, the equilibrium
position moves so as to oppose/reduce the change
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Dynamic equilibrium : forward and backward reactions occurring at same rate
(essential condition: closed system)
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Haber process conditions: Fe catalyst, 200 atm, 400-500 0c
Contact process: 2 atm (greater than 1 up to 5 atm), 400-500 0c , V2O5 catalyst
How is SO3 converted into sulfuric acid: SO3 is dissolved in conc.H2SO4, AND then diluted with
water
Why the SO3 is not first mixed directly with water: very exothermic, OR Creates acid
spray/mist/fog/fumes
Bronsted-Lowry Acid : proton donor
Bronsted-Lowry Base: proton acceptor
Weak: incompletely dissociate into ions
Strong: completely dissociate into ions
Fertiliser problem : fertiliser washed into the river,
leads to excessive growth of algae AND Sunlight is blocked out
O2 is used up and fish die.
Industrial importance of NH3: make fertiliser
Other usage of NH3: produce HNO3
Acid rain: kill plant
Hydrocarbon: compound contains only Hydrogen and carbon
Cracking : break large hydrocarbons into smaller hydrocarbons
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Free radical: species with an unpaired electron
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Structural isomer: molecules with the same molecular formulae, but different structural
formulae/structures
(3 types: chain/position/functional group)
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Stereoisomer: molecules with the same molecular formula and same structural formula, but
different arrangements of atoms in space.
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Geometric isomer: molecules with the same molecular formula and same structural formula, but
different arrangements of atoms in space caused by c=c double bond
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Optical isomer: molecules with the same structural formula, non-superimposable mirror images
Chiral centre: atom with four different groups of atoms attached
High vapor pressure: gas particles in equilibrium with liquid particles, AND greater proportion of
gas particles than liquid particles