chemistry key terms

activation energy (Ea)

Minimum energy that colliding particles must possess for a reaction to occur

addition reaction

A chemical reaction in which two or more substances combine to form a single product.

Aldehydes

a homologous series of organic compounds formed by partial oxidation of primary alcohols.

Avogadro's Law

The principle stating that equal volumes of gases at the same temperature and pressure contain an equal number of molecules.

Bioalcohols

Fuels made from plant matter, often using enzymes or bacteria.

Ketones

a homologous series of organic compounds formed by oxidation of secondary alcohols

bond enthalpy

The enthalpy change when one mole of a bond in the gaseous state is broken

Carboxylic Acids

A homologous series of organic compounds formed by the complete oxidation of primary alcohols.

homologous series

A family of compounds with similar chemical properties whose successive members differ by the addition of a CH2 group

Mean bond enthalpy

The Enthalpy Change needed to break a bond, averaged over different molecules

diol

A diol is an organic compound that contains two hydroxyl (-OH) groups.

Dipole

two charges of equal magnitude but opposite signs are separated by a small distance

Catalytic cracking

a process in which catalysts are used to crack larger hydrocarbon molecules into smaller ones at relatively low temperatures

Cracking

the break down of molecules into shorter ones by heating with a catalyst

bond length

the distance between the nuclei of two covalently bonded atoms

Hydrogen Bonding

the intermolecular force in which a hydrogen atom that is bonded to a highly electronegative atom is attracted to an unshared pair of electrons of an electronegative atom in a nearby molecule

Electronegativity

the ability of an atom to attract a bonding pair of electrons in a covalent bond

covalent bond

A chemical bond that involves sharing a pair of electrons between atoms in a molecule

metalic bond

a bond formed by the attraction between positively charged metal ions and the electrons around them

ionic bond

Formed when one or more electrons are transferred from one atom to another

london forces

the weak attractive forces between molecules resulting from the small, instantaneous dipoles that occur because of the varying positions of the electrons during their motion about nuclei

Hund's Rule

states that single electrons with the same spin must occupy each equal-energy orbital before additional electrons with opposite spins can occupy the same orbitals

Avogadro's constant

Number of atoms of carbon-12 in exactly 12g of carbon-12 atom

molecular mass

Mass per mole of a substance, symbol M, units mol^-1

molecular peak

the peak with the highest m/z ratio in the mass spectrum

concordant titres

those that are close together (usualy withing 0.20cm³)

heterogeneous

two substances in different states are present

1st ionisation energy

relative isotopic mass

stereo isomerism

nucleophile

anhydrous

there is no water

endothermic

heat energy is transferred from the surrounding to the system

incomplete combustion

some of the atoms in the fuel are not fully oxidised

hesses law