AS Chemistry Unit 1 Keywords
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- Created by: Lauren Brown
- Created on: 20-12-12 11:53
Isotopes
Atoms of the same element with different numbers of neutrons.
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Atomic (proton) number
Number of protons in nucleus of an atom
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Mass number
Number of particles (protons & neutrons) in nucleus.
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An ion
Is a positively or negatively charges atom or (covalently bonded) group of atoms (a molecular ion).
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Relative isotopic mass
The mass of an atom of an isotope compared with one-twelfth of the mass of an atom of carbon-12.
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Relative atomic mass
Is the weighted mean mass of an atom of an element compared with one-twelfth of the mass of an atom of carbon-12.
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Relative molecular mass
The weighted mean mass of a molecule compared with one-twelfth of an atom of carbon-12.
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Relative formula mass
The weighted mean mass of a formula unit compared with one-twelfth of the mass of an atom of carbon-12.
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Amount of substance
The quantity whose unit is a mole. Used as a means of counting atoms.
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The Avogadro constant
The number of atoms per mole of the carbon-12 isotope (6.02x10^23 mol^-1)
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A mole
The amount of any substance containing as many particles as there are carbon atoms in exactly 12g of carbon-12 isotope.
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Molar Mass
The mass per mole of a substance. The units of molar mass are gmol^-1.
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Empirical Formula
The simplest whole-number ratio of atoms of each element present in a compound
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A molecule
Small group of atoms held together by covalent bonds
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Molecular formula
Actual number of atoms of each element in a molecule
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Molar Volume
volume par mole of a gas, units are dm^3 mol^-1. At room temperature pressure the molar volume is approximately 24.0 dm^3 mol^-1.
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Concentration
Amount of solute in mol dissolved per 1dm^3 (1000cm^3) of solution
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Standard solution
Solution of known concentration. Normally used in titrations to determine unknown information about another substance.
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Species
Any type of particle that takes part in a chemical reaction
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Stoichiometry
Molar relationship between relative quantities of substances taking part in reaction
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Acid
A species that is a proton donor
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Base
Species that is a proton acceptor
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Alkali
type of base that dissolves in water forming hydroxide ions OH^- (aq) ions.
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Salt
Any chemical compound formed from an acid when H^+ ion from the acid has been replaced by a metal ion or another positive ion.
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Cation
Positively charged ion
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Anion
Negatively charged ion.
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Hydrated
Refers to a crystalline compound containing water molecules
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Anhydrous
Refers to a substance that contains no water molecules
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Water of crystallisation
Refers to water molecules that form an essential part of crystalline structure of a compound.
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Oxidation number
Measure of number of electrons that an atom uses to bond with atoms of another element. Oxidation numbers are derived from a set of rules
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Oxidation
Loss of electrons or an increase in oxidation number
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Reduction
Gain of electrons or decrease in oxidation number
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A redox reaction
A reaction in which both reduction and oxidation take place.
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A reducing agent
A reagent that reduces (adds electrons to) another species
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An oxidising agent
A regent that oxidises (takes electrons from) another species.
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First ionisation energy
Energy required to remove one electron from each atom in one mole of gaseous atoms to form one mole of gaseous 1+ ions.
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Electron shielding
The repulsion between electrons in different inner shells. Shielding reduces the net attractive force from the positive nucleus on the outer-shell electrons.
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Successive ionisation energies
A measure of the energy required to remove each electron in turn
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A shell
A group of atomic orbitals with the same principal quantum number, n. Also known as a main energy level.
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Atomic orbitals
A region within an atom that can hold up two electrons, with opposite spins.
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A sub-shell
A group of the same type of atomic orbitals (s, p, d or f) within a shell.
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An electron configuration
The arrangement of electrons in an atom
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A compound
A substance formed from two or more chemically bonded elements in a fixed ratio, usually shown by a chemical formula
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An ionic bond
The electrostatic attraction between oppositely charged ions.
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A giant ionic lattice
A three-dimensional structure of oppositely charged ions, held together by strong ionic bonds.
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A group
A vertical column in the periodic table. Elements in the same group have similar chemical properties and their atoms have the same number of outer-shell electrons
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A covalent bond
A bond formed by a shared pair of electrons
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A lone pair
An outer-shell pair of electrons that is not involved in chemical bonding.
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A dative covalent or coordinate bond
A shared pair of electrons which has been provided by one of the bonding atoms only.
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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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A permanent dipole
A small charge difference across a bond that results from a difference in the electronegativities of the bonded atom
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A polar covalent bond has a ...
Permanent dipole
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A polar molecule has an...
Overall dipole, when you take into account any dipoles across the bonds
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An intermolecular force
An attractive force between neighbouring molecules
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Permanent dipole-dipole force
A weak attractive force between permanent dipoles in neighbouring polar molecules
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van der Waals’ forces
Attractive forces between induced dipoles in neighbouring molecules.
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Hydrogen bond
A strong dipole-dipole attraction between: 1. An electron-deficient hydrogen atom on one molecule 2. A lone pair of electrons on a highly electronegative atom on a different molecule
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Metallic bonding
The electrostatic attraction between positive metal ions and delocalised electrons
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Delocalised electrons
Shared between more than two atoms
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A giant metallic lattice
A three-dimensional structure of positive ions and delocalised electrons, bonded together by strong metallic bonds.
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A simple molecular lattice
A three-dimensional structure of molecules, bonded together by weak intermolecular forces
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A giant covalent lattice
A three-dimensional structure of atoms, bonded together by strong covalent bonds.
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Period
The horizontal row of elements in the Periodic Table. Elements show trends in properties across a period
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A group
A vertical column in the Periodic Table. Elements in a group have similar chemical properties and their atoms have the same number of outer-shell electrons
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Periodicity
A regular periodic variation of properties of elements with atomic number in the Periodic Table
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Thermal Decomposition
The breaking up of a chemical substance with heat into at least two chemical substances
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Displacement reaction
A reaction in which a more-reactive element displaces and less-reactive element from an aqueous solution of the latter's ions
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Disproportionation
The oxidation and reduction of the same element in a redox reaction
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Precipitation Reaction
The formation of a solid from a solution during a chemical reaction. Precipitates are often formed when two aqueous solutions are mixed together
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Other cards in this set
Card 2
Front
Number of protons in nucleus of an atom
Back
Atomic (proton) number
Card 3
Front
Number of particles (protons & neutrons) in nucleus.
Back
Card 4
Front
Is a positively or negatively charges atom or (covalently bonded) group of atoms (a molecular ion).
Back
Card 5
Front
The mass of an atom of an isotope compared with one-twelfth of the mass of an atom of carbon-12.
Back
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