atom
The smallest object that retains properties of
an element. Composed of electrons and a nucleus (containing protons and
neutrons).
atomic number
Number of protons in an element.
charge
Describes an object's ability to repel or
attract other objects. Protons have positive charges while electrons have
negative charges. Like charges repel each other while opposite charges, such as
protons and electrons, attract one another.
compound
Two or more atoms joined together chemically,
with covalent or ionic bonds.
covalent bonds
When two atoms share at least one pair of
electrons.
double bond
When an atom is bonded to another atom by two
sets of electron pairs.
electron
One of the parts of the atom having a negative
charge. Indivisible particle with a charge of -1.
electronegativity
Measure of a substance's ability to attract
electrons.
Substance consisting of only one type of atom.
empirical formula
Formula showing the simplest ratio of elements
in a compound.
ion
Removing or adding electrons to an atom creates
an ion (a charged object very similar to an atom).
ionic bonds
When two oppositely charged atoms share at least
one pair of electrons but the electrons spend more time near one of the atoms
than the other.
Elements with the same number of protons but
have different numbers of neutrons, and thus different masses.
Lewis structures
A way of representing molecular structures based
on valence electrons.
mass number
The number of protons and neutrons in an atom.
molecular formula
Shows the number of atoms of each element
present in a molecule.
molecule
Two or more atoms chemically combined.
neutral
An object that does not have a positive or
negative charge.
neutron
A particle found in the nucleus of an atom. It
is almost identical in mass to a proton, but carries no electric charge.
orbitals
An energy state in the atomic model which
describes where an electron will likely be.
oxidation number
A number assigned to each atom to help keep
track of the electrons during a redox-reaction.
oxidation reaction
A reaction where a substance loses electrons.
oxidation-reduction-reaction
A reaction involving the transfer of electrons.
periodic table
Grouping of the known elements by their number
of protons. There are many other trends such as size of elements and
electronegativity that are easily expressed in terms of the periodic table.
proton
Particle found in a nucleus with a positive
charge. Number of these gives atomic number.
reduction reaction
A reaction in which a substance gains at least
one electron.
shells
Where the electrons generally are. These shells
are composed of 4 types of electron subshells: s, p, d and f subshells.
single bond
When an electron pair is shared by two atoms.
valence electrons
The electrons in the outermost shell of an atom.
