Definitions Flashcards
(26 cards)
Homogenous mixture
A mixture of uniform composition and in which all components are in the same phase
Heterogenous mixture
A mixture of non-uniform composition and of which the components can be easily identified
Electrical conductor
A material that allows the flow of charge
Electrical insulator
A material that prevents the flow of charge
Thermal conductor
A material that allows heat to pass through easily
Thermal insulator
A material that does not allow heat to pass through it
Diffusion
The movement of atoms or molecules from an area of higher concentration to an area of lower concentration
Boiling point
The temperature of a liquid at which its vapour pressure equals the external (atmospheric) pressure
Melting point
The temperature at which a solid, given sufficient heat, becomes a liquid
Isotope
Atoms of the same element having the same number of protons but a different number of neutrons
Valence electrons
The electrons found in the outermost orbital of an atom
Pauli’s Exclusion Principle
Maximum of two electrons per orbital provided that they spin in opposite directions
Atomic orbitals
The most probable regions in space where electrons that have the specific energy corresponding to the orbital are found
Hund’s Rule
No pairing in p-orbitals before there is at least one electron in each of them
Heisenberg’s Uncertainty Principle
It is impossible to determine both the velocity and the position of an electron at the same time
Atomic radius
The mean distance from the nucleus to the border of the outer orbital
First Ionisation energy
The energy needed per mole to remove the first electron from an atom in the gaseous phase
Electron-affinity
The energy released when an electron is attached to an atom or molecule to form a negative ion
Electronegativity
A measure of the tendency of an atom in a molecule to attract bonding electrons
Mole
Amount of substance having the same number of particles there are atoms in 12g of carbon-12
Relative atomic mass
Mass of a particle on a scale where an atom of carbon-12 has a mass of 12
Molar mass
The mass of one mole of a substance measured in g.mol⁻¹
Empirical formula
The simplest whole-number ratio of atoms in a compound
Water of crystallisation
Water that is stoichiometrically bound into a crystal
