Category 1
A substance that cannot be further divided into simpler substances by chemical methods
Element
the central region of an atom that is made up of the protons and neutrons of the atom; the electrons orbit this
nucleus
a model of the atom in which electrons can only occupy certain shells (or energy levels) moving outwards from the nucleus of an atom
Atomic theory
elements in Group VIII; a group of stable, very unreactive gases
noble gases
molecules containing two atoms
Example: H2
diatomic molecules
A substance formed by the chemical combination of two or more elements in fixed proportions
Compound
An uncharged subatomic particle present in the nucleus of atoms; same relative mass as a proton
neutron
The allowed energies of electrons in atoms; electrons fill these starting with the one closest to the nucleus
electron shells (energy levels)
a shorthand method of representing chemical elements and compounds using the symbols of the elements
chemical formula
chemical bonding formed by the sharing of one or more Paris of electrons between atoms
covalent bonding
Two or more elements or molecules mixed together without being chemically bonded
Mixture
very small particles - protons, neutrons, and electrons - from which all atoms are made
subatomic particles
a shorthand method of describing the arrangement of electrons within the electron shell (or energy levels) of an atom; also referred to as electronic structure
electronic configuration
the strong forces that hold atoms (or ions) together in the various structures that chemical substances can form; this includes metallic bonding, covalent bonding and ionic bonding
chemical bonding
a diagram drawn to represent the bonding in a molecule, or the electrons in an ion; usually, only the outer electrons are shown and they are represented by dots or crosses depending on which atom they are from
dot-and-cross diagram
Electron
the number of protons in the nucleus of an atom
Proton number (or atomic number) (Z)
the number of the vertical column that an element is on the periodic table
group number
a strong electrostatic force of attraction between oppositely charged ions
Ionic bonding
anything that occupies space and has mass
matter
A subatomic particle with a relative atomic mass of 1 and a charge of +1 found in the nucleus of all atoms
Proton
mass number (or nucleon number) (A)
the horizontal row of the periodic table that an element is in
period number
charged particles made from an atom, or groups of atoms (compound ions), but the loss or gain of electrons
ions
a gas or a liquid; able to flow
fluid