Chemistry Revision Notes
Unit One: Atoms, Bonds and Groups
1
, Keywords
• ISOTOPES: Atoms of the same proton number • MOLE: Amount of any substance containing
with different number of neutrons as many particles as there are carbon atoms
• ATOMIC NUMBER: Number of protons in in exactly 12g of carbon-12 isotope
nucleus of an atom • MOLAR MASS: Mass per mole of a
• MASS NUMBER: Number of protons and substance (g mol⁻¹)
neutrons in nucleus • CONCENTRATION: Amount of solute, in
• ION: A positively or negatively charged atom mol, dissolved per 1 dm³ of solution
• RELATIVE ISOTOPIC MASS: Mass of an atom • SPECIES: Type of particle that takes part in
of an isotope compared with 1/12 of the chemical reaction
mass of an atom of carbon-12 • STOICHIOMETRY: Molar relationship
• RELATIVE ATOMIC MASS: Weighted mean between relative quantities of substances
mass of an element compared with 1/12 of taking part in a reaction
the mass of an atom of carbon-12 • ACID: Species that is a proton donor
• RELATIVE MOLECULAR MASS: Weighted • BASE: Species that is a proton acceptor
mean mass of a molecule compared with • ALKALI: Type of base dissolved in water
1/12 of the mass of an atom of carbon-12 forming OH⁻ ions
• RELATIVE FORMULA MASS: Weighted mean • SALT: Any chemical compound formed from
mass of a formula unit compared with 1/12 of an acid, whose protons have been replaced
the mass of an atom of carbon-12 by metal or ammonium ions
• AVOGADRO CONSTANT, NA: Number of • CATION: Positively charged ion
atoms per mole of the carbon-1 isotope (6.02 • ANION: Negatively charged ion
x 10²³ mol⁻¹ 2
,• HYDRATED: Crystalline compound containing • SUCCESSIVE IONISATION ENERGIES:
water molecules Measure of energy required to remove each
• electron in turn
ANHYDROUS: Substance that doesn’t contain
water molecules • 1st IONISATION ENERGY: Energy required to
• remove one mole of electrons from one
WATER OF CRYSTALLISATION: Water
mole of gaseous atoms, forming one mole
molecules that form an essential part of
of uni-positive ions in the gaseous state. X
crystalline structure of a compound
(g) → X⁺ (g) + e⁻
• OXIDATION NUMBER: Measure of number if
• 2nd IONISATION ENERGY: Energy required to
electrons that an atom uses to bond with
remove one mole of electrons from one
atoms of another element- derived from set
mole of unipositive ions in the gaseous
of rules
state. X⁺ (g) → X²⁺ (g) + e⁻
• OXIDATION: Loss of electrons (an increase in
• 3rd IONISATION ENERGY: Energy required to
oxidation number)
remove one mole of electrons from one
• REDUCTION: Gain of electrons (a decrease in mole of X²⁺ ions in the gas phase. X²⁺ (g) →
oxidation number) X³⁺ (g) + e⁻
• REDOX REACTION: Reaction in which both • SHELL: Group of atomic orbitals with same
oxidation and reduction takes place orinciple quantum number, n.- energy levels
• REDUCING AGENT: Reagent that reduces • ATOMIC ORBITAL: Region within an atom
(adds electrons to) another species that can hold up to two electrons, with
• OXIDISING AGENT: Reagent that oxidises opposite spins
(takes electrons from) another species • SUB-SHELL: Group of same type of atomic
• ELECTRON SHIELDING: Repulsion between orbitals (s, p, d, f) within a shell
electrons in different inner shells. • ELECTRON CONFIGURATION: Arrangement
of electrons in an atom 3
, • IONIC BONDING: Electrostatic attraction • HYDROGEN BOND: A strong dipole-dipole
between oppositely charged ions attraction between an electron-deficient
• GIANT IONIC LATTICE: 3D structure of hydrogen atom (O−Hδ⁺, N−Hδ⁺) on one
oppositely charged ions, held together by molecule; and a lone pair of electrons on a
strong ionic bonds highly electronegative atom (H−Oδ⁻ or
• COVALENT BONDING: Bond formed by a H−Nδ⁻) on a different molecule
shared pair of electrons • GIANT METALLIC LATTICE: 3D structure of
• METALLIC BONDING: Electrostatic attraction positive ions and delocalised electrons,
between positive metal ions & delocalised bonded together by strong metallic bonds
electrons • SIMPLE MOLECULAR LATTICE: 3D structure of
• DATIVE BONDING: Shared pair of electrons molecules, bonded together by weak
provided by one of the bonding atoms only intermolecular forces
• LONE PAIR: Outer-shell pair of electrons that • GIANT COVALENT LATTICE: 3D structure of
isn't involved in chemical bonding atoms, bonded together by strong covalent
• ELECTRONEGATIVITY: The ability of an atom bonds
to attract towards it the shared pair of • THERMAL DECOMPOSITION: Breaking up of
electrons in a covalent bond chemical substance with heat into at least
• PERMANENT DIPOLE-DIPOLE: Weak two chemical substance
attractive force between permanent dipoles • DISPLACEMENT REACTION: Reaction in which
in neighbouring polar molecules a more-reactive element displaces a less-
• INTERMOLECULAR FORCE: Attractive force reactive element from an aqueous solution of
between neighbouring molecules the latter’s ions
• VAN DER WAALS’ FORCES: Attractive forces • PRECIPITATION REACTION: Formation of a
between induced dipoles in neighbouring solid from solution during chemical reaction-
molecules when 2 (aq) solutions are mixed together 4
Unit One: Atoms, Bonds and Groups
1
, Keywords
• ISOTOPES: Atoms of the same proton number • MOLE: Amount of any substance containing
with different number of neutrons as many particles as there are carbon atoms
• ATOMIC NUMBER: Number of protons in in exactly 12g of carbon-12 isotope
nucleus of an atom • MOLAR MASS: Mass per mole of a
• MASS NUMBER: Number of protons and substance (g mol⁻¹)
neutrons in nucleus • CONCENTRATION: Amount of solute, in
• ION: A positively or negatively charged atom mol, dissolved per 1 dm³ of solution
• RELATIVE ISOTOPIC MASS: Mass of an atom • SPECIES: Type of particle that takes part in
of an isotope compared with 1/12 of the chemical reaction
mass of an atom of carbon-12 • STOICHIOMETRY: Molar relationship
• RELATIVE ATOMIC MASS: Weighted mean between relative quantities of substances
mass of an element compared with 1/12 of taking part in a reaction
the mass of an atom of carbon-12 • ACID: Species that is a proton donor
• RELATIVE MOLECULAR MASS: Weighted • BASE: Species that is a proton acceptor
mean mass of a molecule compared with • ALKALI: Type of base dissolved in water
1/12 of the mass of an atom of carbon-12 forming OH⁻ ions
• RELATIVE FORMULA MASS: Weighted mean • SALT: Any chemical compound formed from
mass of a formula unit compared with 1/12 of an acid, whose protons have been replaced
the mass of an atom of carbon-12 by metal or ammonium ions
• AVOGADRO CONSTANT, NA: Number of • CATION: Positively charged ion
atoms per mole of the carbon-1 isotope (6.02 • ANION: Negatively charged ion
x 10²³ mol⁻¹ 2
,• HYDRATED: Crystalline compound containing • SUCCESSIVE IONISATION ENERGIES:
water molecules Measure of energy required to remove each
• electron in turn
ANHYDROUS: Substance that doesn’t contain
water molecules • 1st IONISATION ENERGY: Energy required to
• remove one mole of electrons from one
WATER OF CRYSTALLISATION: Water
mole of gaseous atoms, forming one mole
molecules that form an essential part of
of uni-positive ions in the gaseous state. X
crystalline structure of a compound
(g) → X⁺ (g) + e⁻
• OXIDATION NUMBER: Measure of number if
• 2nd IONISATION ENERGY: Energy required to
electrons that an atom uses to bond with
remove one mole of electrons from one
atoms of another element- derived from set
mole of unipositive ions in the gaseous
of rules
state. X⁺ (g) → X²⁺ (g) + e⁻
• OXIDATION: Loss of electrons (an increase in
• 3rd IONISATION ENERGY: Energy required to
oxidation number)
remove one mole of electrons from one
• REDUCTION: Gain of electrons (a decrease in mole of X²⁺ ions in the gas phase. X²⁺ (g) →
oxidation number) X³⁺ (g) + e⁻
• REDOX REACTION: Reaction in which both • SHELL: Group of atomic orbitals with same
oxidation and reduction takes place orinciple quantum number, n.- energy levels
• REDUCING AGENT: Reagent that reduces • ATOMIC ORBITAL: Region within an atom
(adds electrons to) another species that can hold up to two electrons, with
• OXIDISING AGENT: Reagent that oxidises opposite spins
(takes electrons from) another species • SUB-SHELL: Group of same type of atomic
• ELECTRON SHIELDING: Repulsion between orbitals (s, p, d, f) within a shell
electrons in different inner shells. • ELECTRON CONFIGURATION: Arrangement
of electrons in an atom 3
, • IONIC BONDING: Electrostatic attraction • HYDROGEN BOND: A strong dipole-dipole
between oppositely charged ions attraction between an electron-deficient
• GIANT IONIC LATTICE: 3D structure of hydrogen atom (O−Hδ⁺, N−Hδ⁺) on one
oppositely charged ions, held together by molecule; and a lone pair of electrons on a
strong ionic bonds highly electronegative atom (H−Oδ⁻ or
• COVALENT BONDING: Bond formed by a H−Nδ⁻) on a different molecule
shared pair of electrons • GIANT METALLIC LATTICE: 3D structure of
• METALLIC BONDING: Electrostatic attraction positive ions and delocalised electrons,
between positive metal ions & delocalised bonded together by strong metallic bonds
electrons • SIMPLE MOLECULAR LATTICE: 3D structure of
• DATIVE BONDING: Shared pair of electrons molecules, bonded together by weak
provided by one of the bonding atoms only intermolecular forces
• LONE PAIR: Outer-shell pair of electrons that • GIANT COVALENT LATTICE: 3D structure of
isn't involved in chemical bonding atoms, bonded together by strong covalent
• ELECTRONEGATIVITY: The ability of an atom bonds
to attract towards it the shared pair of • THERMAL DECOMPOSITION: Breaking up of
electrons in a covalent bond chemical substance with heat into at least
• PERMANENT DIPOLE-DIPOLE: Weak two chemical substance
attractive force between permanent dipoles • DISPLACEMENT REACTION: Reaction in which
in neighbouring polar molecules a more-reactive element displaces a less-
• INTERMOLECULAR FORCE: Attractive force reactive element from an aqueous solution of
between neighbouring molecules the latter’s ions
• VAN DER WAALS’ FORCES: Attractive forces • PRECIPITATION REACTION: Formation of a
between induced dipoles in neighbouring solid from solution during chemical reaction-
molecules when 2 (aq) solutions are mixed together 4
