Chemistry Definitions

  • Created by: Ellen2745
  • Created on: 28-04-18 21:36
Atomic number
The number of protons in a nucleus
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Mass number
The number of protons and neutrons in a nucleus
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Isotopes
Atoms with the same number of protons but different number of neutrons
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Relative atomic mass
The weighted mean mass of an atom of an element compared to 1/12 of an atom of carbon-12
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Relative isotopic mass
The mass of an atom of an isotope compared with 1/12 of an atom of carbon-12
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Acid
A species that releases H+ ions in aqueous solution (H+ donor)
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Base
A compound that neutralises an acid to form a salt (H+ accepter)
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Salt
A product of a reaction in which the H+ ions from the acid are replaced by metal or ammonium ions
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Neutralisation
The reaction between and acid and a base to produce a salt, H+ + OH- = H20
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Strong acid
An acid that completely dissociates in aqueous solution
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Weak acid
An acid that partially dissociates in aqueous solution
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Anhydrous
Containing no water molecules
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Hydrated
A crystalline compound containing water molecules
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Water of crystallisation
Water molecules that are bonded into a crystalline structure of a compound
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Mole
The amount of any substance containing as many elementary particles as there are carbon atoms in exactly 12g of carbon-12. 6.02x10 23
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Avogadro constant
6.02x10 23 mol-1, the number of atoms per mole of carbon-12
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Molar mass
The mass per mole of a substance, in units of g mol-1
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Molar gas volume
The volume of gas molecules at a stated temperature and pressure
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Empirical formula
A formula that shows the simplest whole-number ratio of atoms of each element present in a compound
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Molecular formula
A formula that shows the number and type of atoms of each element present in a molecule
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Orbital
A region around a nucleus that can hold 2 electron, with opposite spins
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Ionic bonding
The electrostatic attraction between positive and negative ions
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Covalent bonding
The strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms
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Dative covalent (co-ordinate) bonding
A shared pair of electrons in which the bonded pair has been provided by one of the bonded atoms only
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Metallic bonding
The electrostatic attraction between positive metal ions and delocalised electrons
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Electronegativity
A measure of the attraction of a bonded atom for the pair of electrons in a covalent bond
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Periodicity
A repeating trend of the elements across each period of the periodic table
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First ionisation energy
The energy required to remove one electron from each atom in one mole of gaseous atoms of an element to form one mole of gaseous 1+ ions
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Oxidation
Loss of electrons/ an increase in oxidation number
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Reduction
Gain of electrons/ a decrease in oxidation number
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Redox
a reaction involving reduction and oxidation
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Disproportionation
A redox reaction in which the same element is oxidised and reduced
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Activation energy
The minimum energy required to start a reaction by the breaking of bonds
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Enthalpy change of formation
the enthaply change when one mole of a compound is formed from its elements under standard conditions in their standard states
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Enthalpy change of combustion
the enthalpy change when one mole of a substance reacts completely with oxygen under standard conditions in standard states
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Enthalpy change of neutralisation
the enthalpy change that accompanies the reaction of an acid by a base to form one mole of H2O, under standard conditions in standard states
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Average bond enthalpy
The average enthalpy change that takes place when breaking by homolytic fission one mole of given type of bond in the molecules of a gaseous species
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Homogenous catalyst
A reaction in which the catalyst and reactants are in the same physical state
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Heterogeneous catalyst
A reaction in which the catalyst has a different physical state from the reactants
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Homologous series
A series of organic compounds with the same functional group but with each successive member differing by CH2
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Saturated
Containing single bonds only
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Unsaturated
Containing multiple carbon-to-carbon bonds
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Aliphatic
Containing carbon atoms joined together in unbranched (straight) or branched chains
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Alicyclic
Containing carbon atoms joined together in a ring that isn't aromatic
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Aromatic
Containing one or more benzene rings
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Structural isomers
Compounds with the same molecular formula but different structural formaulae
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Stereoisomers
Compounds with the same structural formula but with different arrangement of the atoms in space
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Homolytic fission
The breaking of a covalent bond with one of the bonded electrons going to each atom, forming two radicals
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Heterolytic fission
The breaking of a covalent bond forming a cation(positive ion) and an anion (negative ion)
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Radical
A species with an unpaired electron
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Curly arrow
The movement of a pair of electrons from heterolytic fission
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Addition reaction
A reaction in which a reactant is added to an unsaturated molecule to make a one saturated molecule
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Substitution reaction
A reaction in which one atom or group of atoms is replaced by another atom or group of atoms
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Electrophile
An atom or group of atoms that is attracted to an electron-rich centre, where it accepts a pair of electrons
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Nucleophile
An atom or group of atoms that is attracted to an electron-deficient carbon atom, where it donates a pair of electrons to form a new covalent bond
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Other cards in this set

Card 2

Front

The number of protons and neutrons in a nucleus

Back

Mass number

Card 3

Front

Atoms with the same number of protons but different number of neutrons

Back

Preview of the back of card 3

Card 4

Front

The weighted mean mass of an atom of an element compared to 1/12 of an atom of carbon-12

Back

Preview of the back of card 4

Card 5

Front

The mass of an atom of an isotope compared with 1/12 of an atom of carbon-12

Back

Preview of the back of card 5
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