Matter

 is anything that occupies space and has mass

mass

is the quantity of matter an object has

Element

are substances that cannot be broken down chemically into simpler kinds of matter

Atom

the simplest particle of an element that retains all of the properties of that element 

Nucleus

makes up the bulk of the mass of the atom and consists of two kinds of subatomic particles, a proton and a neutron

Atomic number

 the number of protons in an atom

electrons

in an atom, the number of positively charged protons is balanced by an equal number of small,negatively charged particles

orbital

is a three dimensional region around a nucleus that indicates the probable location of an electron

isotopes

Atoms of the same element that have a different number of neutrons

compounds

are made up of atoms of two or more elements in fixed proportions

chemical bonds

are the attractive forces that hold atoms together

covalent bond

forms when two atoms share one or more pairs of electrons

molecule

is the simplest part of a substance that retains all of the properties of tat substance and can exist and can exist in a  free state

ion

an atom or molecule with an electrical charge

ionic bond

Because positive and negative electrical charges attract each other, the sodium ion and chloride ion attract each other