Important definitions

The list of definitions in these flashcards are important to know verbatim for tests and exams. All definitions are according to the CAPS Document.

Element

The simplest pure substance which cannot be broken down further by chemical means.

Compound

A pure substance consisting of more than one element that can be broken down by chemical means.

Pure Substance

A substance consisting of more than one element or one compound.

Atomic Number

The position of an element on the Periodic Table.

Isotopes

Atoms of the same element with different numbers of neutrons.

Ionization Energy

The amount of energy required to remove an electron from an atom or molecule.

Electron Affinity

The amount of energy released when an electron is added to a neutral atom to form an ion.

Electronegativity

A measure of the tendency of an atom to attract a bonding pair of electrons.

Pulse

A single disturbance in a medium.

Transverse wave

The particles of the medium move at right angles to the direction of propagation of the pulse.

Constructive interference

The result of superposition of pulses causing an increase in the amplitude of the disturbance.

Deconstructive interference

The result of superposition of the pulses causing a decrease in the amplitude of the disturbance.

Wavelength of a wave

The disturbance between two adjacent points in phase.

Frequency of a wave

The number of full cycles a wave completes per second, measured in hertz (Hz).

Period of a wave

The time taken for a wave to complete one full cycle.

Crest of a wave

The highest point on a wave.

Trough of a wave

The lowest point on a wave.

Amplitude of a longitudinal wave

The maximum disturbance of a particle from its rest (equilibrium) position.

Compression

A region of high pressure where particles are close together.

Rarefaction

A region of low pressure where particles are spread apart.

Hund’s rule

Electrons would rather be in a subshell on their own than share an orbital.

Pauli’s (exclusion) principle

Electrons have a property known as spin.

Two electrons in an orbital will spin in opposite directions.

The principle of conservation of charge

The net charge of an isolated system remains constant during any physical process.

The principle of charge quantization

The charge of any object is an integer multiple of the elementary charge qe = 1,6 × 10^ -19C

Melting point

The temperature at which a solid changes phase to become a liquid.

Boiling point

The temperature of a liquid where its vapour pressure is equal to the external atmospheric pressure.