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Key Words
Elements of Life.
Absorption Spectrum
This is produced when electrons move from a lower energy level
to a higher one. It looks like a rainbow with black lines on it.
Acid
Has a pH less than 7. Acid and alkali  salt + water
Alkali
Has a pH great than 7 Alkali + acid  salt + water
Alloy
A mixture of metals e.g. brass is a mixture of copper and zinc.
Alpha radiation ()
The particle produced when the nucleus breaks down is an .
particle or helium nucleus. It is composed of 2 protons and 2
neutrons
The amount of a substance is the number of moles of a substance.
Amount
Atomic number
Atomic volume
Avogadro constant (L)
Beta radiation ()
Covalent bonds
Dative covalent bond
Electronegativity
Emission spectrum
Empirical formula
This is sometimes called the proton number. It tells you the
number of protons in the nucleus. All atoms of a particular
element have the same atomic number
The volume occupied by 1 mole of an element.
This is the number of particles in a mole of a substance L = 6.02 x
1023 mol –1.
When a nucleus emits beta radiation, the particle lost from the
nucleus is an electron. To produce the electron, a neutron is first
converted into a proton and an electron.
These are formed between two non-metal atoms. Noble gas
configuration (full outer shell) is attained by sharing pairs of
electrons. The electrostatic attraction between both nuclei and
the pair of electrons holds the atoms together.
A covalent bond in which both of the shared pair of electrons
come from the same atom.
A measure of an atom’s attraction for bonding electrons – it’s
‘electron pulling power’. The more electronegative of a pair of
atoms will gain the - charge.
This is produced when electrons move from a higher to a lower
energy level. It is coloured lines on a dark background
The empirical formula tells you the simplest ratio of the
different atoms in a compound.
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First ionisation
enthalpy
Frequency (
Fusion
Gamma radiation ()
Group
Half life
Ionising radiation
Isomers
Isotopes
Mass number
Metallic bond
Molar mass
Mole (mol)
Molecular formula
The energy needed to remove one electron from every atom
in 1 mole of a gaseous element
X(g)  X+(g) +eThis is the number of vibrations per second. The units are
Hertz (Hz). E=h. h is the Planck constant and is 6.6.3 x
10-34 J Hz-1.. E is energy in joules (J).
The joining together of 2 small nuclei to make one larger
one. Approach is at high speed to overcome repulsion
between positive nuclei.
When alpha or beta radiation are emitted, often gamma
radiation is emitted too. Gamma radiation is not made of
particles; it is part of the electromagnetic spectrum.
A vertical column in the periodic table. The elements in a
group show similarities since they have the same number of
electrons in the outer shell.
The time taken for half of the nuclei in a sample to decay.
Sometimes alpha, beta or gamma radiations are called
ionising radiations. If one of these emissions hits an atom
(in air for instance), an electron is knocked off. A positive
ion is made.
Two compounds with the same molecular formula but
different structural formulae.
Atoms of the same element which have different mass
numbers/numbers of neutrons. The atomic number of the 2
atoms is the same.
This is the total of the numbers of protons and numbers of
neutrons in the nucleus.
These are found in metallic elements. Delocalised outer shell
electrons are attracted to the positive nuclei in the lattice.
The molar mass of a substance is the mass of 1 mole of it.
For elements, the molar mass = relative atomic mass (in g).
For compounds, the molar mass = relative formula mass (in g)
A mole of a substance is 6.02 x 1023 particles of it.
The molecular formula tells you the actual numbers of the
different atoms in a compound.
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Period
Periodicity
pH
Polar bond
Radioactive
Radioactive decay
Relative atomic mass
(Ar)
Relative molecular
mass (Mr)
Thermal decomposition
Thermal stability
A horizontal row in the periodic table. Elements change
from metallic to non-metallic across a period.
If a property varies in a fairly regular way across a period
and this same regular variation is shown in each period then
we have periodic patterns or periodicity.
This indicates how strongly acidic or alkaline a solution is.
pH1 is a very strong acid, pH7 is neutral and pH14 is a very
strong alkali.
A bond formed between two atoms with different
electronegativity values. One atom is +, the other -.
Radioactive isotopes have nuclei which spontaneously break
down. The nucleus is unstable.
The spontaneous breakdown of an isotope’s nucleus. It can
be fast or slow.
This is the mass of the atoms of an element relative to an
atom of carbon – 12.
This is the mass of a molecule of a compound relative to an
atom of carbon –12. It is sometimes called relative formula
mass. To work it out, add up the relative atomic masses for
each atom in the formula.
This is the breaking down of a compound using heat.
A compound with the greatest thermal stability is the one
which needs the highest temperature to decompose it.