Unit 1 chemistry - definitions

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A-Levels Chemistry Flashcards on Unit 1 chemistry - definitions, created by ChloC on 16/05/2013.
ChloC
Flashcards by ChloC, updated more than 1 year ago
ChloC
Created by ChloC almost 11 years ago
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Question Answer
Relative isotopic mass The mass of an atom of the isotope, compared with one-twelfth of the mass of carbon-12.
Relative molecular mass The weighted mean mass of a molecule, compared with one-twelfth of the mass of carbon-12.
Anhydrous A molecule containing no water molecules
Simple molecular lattice A 3-D structure of molecules, bonded together by weak intermolecular forces.
Shell A group of atomic orbitals with the same principal quantum number/same main energy level.
Alkali A type of base that dissolves in water, forming hydroxide ions.
1st Ionisation energy The energy required to remove one electron in each atom in one mole of gaseous atoms, to form one mole of gaseous 1+ ions.
Ion A positively or negatively charged atom.
Acid A proton donor
Intermolecular force An attractive force between neighbouring molecules.
2nd Ionisation energy The energy required to remove an electron from each ion in one mole of gaseous 1+ ions, to form one mole of gaseous 2+ ions.
Successive ionisation energies A measure of the energy required to remove each electron in turn.
Hydrogen bond A strong dipole dipole set traction, between an electron deficient hydrogen atom on one molecule, and a highly electronegative molecule (O,N) on another.
Period A horizontal row of elements in the periodic table, showing trends.
Salt A chemical compound formed from an acid, when a H+ ion from the acid has been replaced by a metal ion or another positive ion.
Periodicity A regular periodic variation of properties of elements with atomic number and position in the periodic table.
Hydrated Crystalline and containing water molecules
Group A vertical column in the periodic table, involving elements with the same number of electrons in their outer shell, and similar chemical properties.
Reduction A gain of electrons and loss in oxidation number.
Oxidation A loss in electrons and gain in oxidation number
Electronegativity A measure of the attraction of a bonded atom, for the pair of electrons in a covalent bond.
Reducing agent A reagent that reduces/adds electrons to another species.
Giant metallic lattice A three dimensional structure of positive ions and delocalised electrons, held together by strong metallic bonds.
Oxidising agent A reagent that increases/removes electrons from mother species.
Electron configuration The arrangement of electrons in an atom.
Giant ionic lattice A three dimensional structure of positive and negative ions held together by strong ionic bonds.
Redox reaction A reaction involving both reduction and oxidation.
Principal quantum number A number representing the relative overall energy level for each orbital, which increases with distance from the nucleus.
Thermal decomposition The breaking up of a chemical substance, with heat into at east two different substances.
Oxidation number A measure of the number of electrons that an atom uses to bond with atoms of another element.
Giant covalent bond A three dimensional structure of atoms, bonded together by strong covalent bonds.
Van der waals forces Very weak attractive forces between induced dipoles in neighbouring molecules.
Sub-shell A group of the same type of atomic orbitals e.g. s,p,d,f
Molecule A small group of atoms held together by a covalent bond
Empirical formulae The simplest, whole number ratio of atoms of each element present in. Compound.
Polar molecule A molecule that has an overall dipole, taking into account any dipoles across bonds.
Polar covalent bond A bond with a permanent dipole.
Electron shielding The repulsion between electron in different inner shells.
Permanent dipole-dipole force An attractive force between permanent dipoles in neighbouring polar molecules.
Permanent dipole A small charge difference across a bond resulting from a difference in electronegativities of the bonded atoms.
Disproportionation The oxidation and reduction of the same element in a redox reaction.
Displacement reaction A reaction in which a more active element displaces a less active element from an aqueous solution of the latter's ions.
Delocalised electrons Electrons that are shared between more than two atoms
Dative covalent bond A shared pair of electrons which has been provided by one of the bonding atoms only.
Covalent bond A bond formed by a shared pair of electrons
Concentration The amount of solute, in moles per 1000cm3 of solution.
Compound A substance formed by two or more chemically bonded elements in a fixed ratio, usually shown by a chemical formula
Cation A positively charged ion
Molecular formula The number of atoms of each element in a molecule.
Mole The amount of any substance containing as many particles as there are carbon atoms in exactly 12g of carbon-12 isotope.
Molar volume The volume per mole of a gas.
Catalyst A substance that increases the rate of a chemical reaction by providing a smaller activation energy and alternative reaction pathway, and is not used up in the process.
Molar mass (M) The mass per mole of a substance.
Base A species that is a proton acceptor
Metallic bond The electrostatic attraction between fixed positive ions and a sea of delocalised electrons.
Mass number The number of protons and neutrons in the nucleus.
Avogadro constant The number of atoms per mole of the carbon-12 isotope 6.023x10 to the power of 23
Lone pair An outer shell pair of electrons that are not involved in chemical bonding.
Atomic number The number of protons in the nucleus
Limiting reagent The substance in a chemical reaction that runs out first.
Stoichiometry The molar relationship between the relative quantities of substances taking part in a reaction.
Standard solution A solution of known concentration. (Normally used in titrations)
Species Any type of particle that takes part in a reaction.
Isotopes Atoms of the same element with different mass numbers and different number of neutrons in the nucleus (but the Same proton number)
Orbital A region of space within an atom that can hold up to two electrons with opposite spins.
Relative atomic mass The weighted mean mass of an atom of an element, compared with one-twelfth of the mass of carbon-12 which is taken as 12 exactly
Spectator ions Ions that are present, but do it take part in the chemical reaction.
Ionic bond The electrostatic attraction between oppositely charged ions.
Relative formula mass The weighted mean mass of a formula unit, compared with one-twelfth of the mass of carbon-12.
Anion A negatively charged ion
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