Definitions Flashcards
Atomic orbitals?
A region around the nucleus that can hold up to two electrons with opposite spin.
What is the 1st ionisation energy?
Energy required to remove one mole of electrons from one mole of gaseous atoms producing ions of charge +1.
What is ionic bonding?
Electrostatic attraction between positive and negatively charged ions.
What is a covalent bond?
The strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms.
What is a dative covalent bond?
A covalent bond in which the shared pair of electrons has been provided by one of the bonding atoms only.
What is electronegativity?
The ability of an atom to attract the bonding electrons in a covalent bond.
What is a dipole?
The difference in charge between two atoms caused by a shift in electron density in the bond.
What are intermolecular forces?
Forces between molecules.
What is metallic bonding?
The strong electrostatic attraction between positive ions and negatively charged delocalised electrons in a regular lattice.
What is a mole?
Amount of substance containing as many particles as there are carbon atoms in exactly 12g of C-12.
What is Avogadro’s constant?
Number of particles per mole of a substance.
What is empirical formula?
Simplest whole number ration of atoms to each element present in a compound.
What is molecular formula?
Number and type of atoms of each element in a molecule.
What is the titre?
The final reading off the burette taken from the initial reading.
What is water of crystallisation?
Number of water molecules chemically combined in a definite molecular proportion, with the salt in its crystal state.
What does hydrated mean?
A solid salt containing water of crystallisation.
What does anhydrous mean?
A salt which doesn’t contain water of crystallisation.
What is oxidation?
The loss of electrons and the increase in oxidation number.
What is reduction?
The gain of electrons and a reduction in oxidation number.
What are redox reactions?
When oxidation and reduction occur simultaneously in a reaction.
What is enthalpy of combustion?
Enthalpy change for the complete combustion of 1 mole of a substance.
What is enthalpy of formation?
When 1 mole of a substance is formed from its elements.
What is a homologous series?
A series of organic compounds having the same functional group but with each successive member differing by CH2.
What are structural isomers?
Compounds with the same molecular formula but different structural formula.
What is a radical?
A species with an unpaired electron.
What are stereoisomers?
Same structural formula but with a different arrangement in space.
What is E/Z isomerism?
Example of stereoisomerism, in terms of restricted rotation about a double bond and the requirement for two different groups to be attached to each carbon atom of the C=C group.
What is cis-trans isomerism?
A special case of E/Z isomerism in which two of the substituent groups are attached to each carbon atom of the C=C group are the same.
What are electrophiles?
Electron pair acceptors.
What are alkanes?
Saturated hydrocarbons containing single C-C and C-H bonds as sigma bonds.
What are sigma bonds?
Overlap of orbitals directly between the bonding atoms.
What are the standard conditions?
298K, 1atm, 1moldm-3
What is average bond enthalpy?
Breaking 1 mole of bonds in gaseous molecules.
What is a heterogenous catalyst?
One that is in a different phase from the other reactants.
What is a homogenous catalyst?
One in the same phase as the reactants.
What is a nucleophile?
An electron pair donor.
What are CFCs?
Organic compounds that only contain chlorine, fluorine and carbon.
What is the atomic number?
Number of protons in the nucleus.
What is the mass number?
Total number of protons and neutrons in the nucleus.
What is an isotope?
Atoms of an element with the same number of protons but different number of neutrons.
What is the RAM?
Weighted mean mass compared with 1/12th mass of carbon-12.
What is relative isotopic mass?
Mass of ab isotope compared with 1/12th mass of carbon-12.
What are giant covalent lattices?
Huge networks of covalently bonded atoms.
What are allotropes?
Different forms of the same element in the same state.
What is a salt?
When the H+ in an acid is replaced by a metal ion / ammonium ion.
What is enthalpy change of neutralisation?
Formation of 1 mole of water from neutralisation.
