ISOTOPES

ATOMIC NUCLEUS HAS POSITIVELY CHARGED PROTONS (p) AND NEUTRALLY CHARGED NEUTRONS (n) ORBITED BY NEGATIVELY CHARGED ELECTRONS (e)

ELEMENT DEFINED BY ATOMIC NUMBER - NUMBER OF PROTONS

DIFFERENT ISOTOPES HAVE DIFFERENT NUMBERS OF NEUTRONS

AND SO DIFFERENT ATOMIC WEIGHTS (# n + p)

EXAMPLE: CARBON - ATOMIC NUMBER 6

CARBON 12 CARBON 13 CARBON 14

SOME ISOTOPES ARE RADIOACTIVE OR UNSTABLE -

NEUTRON DECAYS INTO PROTON PLUS ELECTRON

CARBON 14 -> NITROGEN 14 + ELECTRON

6p, 8n 7p, 7n e