Important Definitions Flashcards
First ionisation energy
The energy required to remove one electron from each atom in a mole of gaseous atoms of an element to form one mole of gaseous 1+ ions.
Relative atomic mass
The weighted mean mass of an atom of an element compared with one-twelfth of the mass of an atom of carbon-12.
Orbital
A region within an atom that can hold up to two electrons with opposite spins.
Ionic bonding
The electrostatic attraction between positive and negative ions.
Covalent bonding
The strong electrostatic attraction between a shared pare of electrons and the nuclei of the bonded atoms.
Coordinate bond/ dative covalent bond
A shared pair of electrons in which the bonded pair has been provided by one of the bonding atoms only.
Weak acid
Partially dissociates in water.
Le Chatelier’s principle
When a system in dynamic equilibrium is subjected to an external change, the system readjusts itself to minimise the effect of the change and to restore equilibrium.
Hess’s law
If a reaction can take place by more than one route and the initial and final conditions are the same, the total entrance,lay change is the same for each route.
Rate of reaction
The change in concentration of a reactant or a product in a given time.
Mole
The amount of any substance containing as many elementary particles as there are carbon atoms in exactly 2g of the carbon-12 isotope, that is 6.02x10^23 particles.
Catalyst
A substance that increase the rate of a chemical reaction without being used up in the process; a catalyst provides an alternative route for the reaction with a lower activation energy.
Metallic bonding
The electrostatic attraction between positive metal ions and delocalised electrons
Sub shell
A group of orbitals of the same type within a shell
Homolytic fission
The breaking of covalent bond with one of the bonded electrons going to each atom, forming two radicals
