Chemistry Definitions (all)

Acid (Arrhenius)

Produces hydrogen ion by dissociation in water

Acid (Bronsted-Lowry)

Proton donor

Acidic oxide

Oxide that lowers pH in water

Catalyst

Substance that alters the rate of a reaction and is not used up

Addition polymerisation

Monomers combining to form a large molecule

Adsorption

Method of attachment of gaseous or liquid molecules to a solid surface

Atomic absorption spectrometry

Instrumental method used to analyse water for heavy metals

Atomic number

Number of protons in nucleus

Atomic orbitals

Region around nucleus in which there is high probability of finding an electron

Atomic radius

Half the distance between singly bonded atoms of the same element

Atomic sub-level

Sub-division of a main energy level consisting of one or more orbitals of the same energy

Auto ignition

Tendency to premature ignition

Avogadros law

Equal volumes of gas contain equal numbers of molecules under the same conditions of temperature and pressure

Base (Arrhenius)

Produces OH- as only anion in aqueous solution

Base (brinsted-Lowry)

Proton acceptor

Biochemical oxygen demand

Amount of oxygen consumed in ppm when sample kept in dark for 5 days at 20 degrees

Catalytic cracking

Splitting of long chain molecules by heat and catalsyt(s)

Bond energy

Average amount of energy required to break 1 mole of bonds into separate atoms in the gaseous state

Catalytic poison

Substance that blocks the active state of a catalyst and it stops working

Charles’ Law

V/T = k

Chemical equilibrium

Rate of forward reaction = rate of reverse reaction

Chromotagraphy

Separation of a mixture of components based on their relative attractions for a stationary phase while carried by a mobile phase

Condensation reaction

Production of a more complex molecule with formation of an unsaturated compound by loss of a small molecule

Conjugate acid (bronsted Lowry)

Produced by gain of one proton

Conjugate pair

Acid-base differing by proton

Covalent bond

Involving sharing one or more pairs of electrons

Crystals

Consisting of particles in a lattice

Dobereiners Triads

Elements of similar properties in groups of 3

Dynamic

Reaction has not stopped

Effective collision

One that results in a reaction

Electrolysis

Chemical reaction caused by electric current passing through an electrolyte

Electronegativity

Measure or a relative attraction for shared electrons

Element

An element cannot be broken down into anything simpler

Emulsion

A suspension of oil droplets in water

Energy level

Shell which electrons of equal energy can occupy

Equilibrium

Rate of forward reaction = rate of reverse reaction

Eutrophication

Excess plant growth caused by excess nutrient in water

Excited state

Higher energy state

Feedstock

Modified and purified raw materials

First ionisation energy

Minimum energy to remove most loosely bound electron from isolated atom in ground state

Flocculation

Clumping of suspended solids in water

Gay Loussac’s Law

The volumes of reacting gases are in whole number ratios

Greenhouse factor

Effect compared with carbon dioxide

Greenhouse effect

Blocking the escape of radiation by gases in the atmosphere

Greenhouse gas

Atmospheric gas that prevents escape of heat

Ground state

In lowest energy level

Half Life

Time taken for half of the nuclei in sample to decay

Hard water

Water which does not easily form lather with soap (forms scum instead)

Hardness Temporary

Removed by boiling

Hardness

Not removed by boiling

Heat of combustion

One mole is burned completely in excess oxygen

Heat of formation

1 mole formed from elements in their standard states

Heat of reaction

Number of moles of reactants in the balanced equation react completely

Heisenberg’s Uncertainty Principle

It is not impossible to measure exact position and velocity of electron at the same time

Heterogeneous catalyst

Reactants and catalyst in different phases

Homogenous catalyst

Reactants and catalyst in the same phase

Homologous series

Have the same general formula

Hydrocarbon

Carbon and hydrogen

Ideal gas

A gas that obeys the gas laws at all temperature and pressure

Immiscible Liquids

Do not mix or do not dissolve in each other

Isomers

Same molecular formula but different structural formula

Isotopes

Same element different mass numbers due to different number of neutrons

Intermolecular

Between molecules

Intramolecular

Between atoms in a molecule

Kw

(H+)(OH-)

Le Chatelier’s Principle

Equilibrium oppose applied stresses

Limiting Reagent

Totally consumed when chemical reaction is complete

Mass number

Number of nucleons (protons and neutrons)

Nitrogen fixation

Conversion of atmospheric nitrogen to compounds that can be used

Octane number

Tendency of a fuel to auto ignite

Oxidation

In read ein oxidation number

pH

-log10(H3O+)

Pi Bond

“Side-on” overlap of p-orbitals

Primary standard

Pure, stable, high molecular mass substance of known concentration

Primary Treatment

Removal of solids by screening and settlement

Radioactivity

Spontaneous breaking up of nucleus to release radiation

Rate of reaction

Change in concentration per unit of time

Reduction

Decrease in oxidation number

Relative atomic mass

Average mass of atoms

Reversible

Can go in both directions

Scrubbing

Method of removing pollutants from industrial chimney gases

Secondary treatment

Biological oxidation

Sigma bond

Head on overlap of orbitals

Standardised

Concentration got by titration

Strong acid (bronsted-Lowry)

Good proton donor

Strong acid (Arrhenius)

Completely dissociate

Tertiary treatment

removal of nitrates and phosphates

Unsaturated

Having one carbon to carbon double or triple bond

Volatile

Easily vaporised

Weak acid

Poor proton donor