Atoms and Molecules


Matter is made up of elements


Atom is the smallest piece of an element.  It contains:






            Atomic number

            Mass number



Forming chemical bonds -- 7 simple rules to understanding chemical reactivity

Not all atoms are equally reactive (that is, elements differ)

Reactivity is based on the arrangement of electrons (not MP, BP)

Only valence electrons matter (valence electrons are in the outer orbital)

Atoms whose outer shell is full are non-reactive

In larger orbitals, 8 valence electrons is non-reactive

Chemical reactions lead to all atoms having stable electron configurations

Atoms form chemical bonds by gaining, losing, or sharing electrons