•
•Atoms
contain 3 kinds of particles:
–Electrons – in orbits Negatively charged Very low mass (1/1836 mp)
–Protons -- in
nucleus Positively
charged
More “massive”
–Neutrons – in nucleus Electrically neutral mn » mp
–
•# of
protons (Z) determines charge of nucleus Þ electrical properties Þ element
–Chemical reactions involve sharing/exchanging
electrons (See periodic table A-16)
–Hydrogen:
Z=1
–Helium: Z=2
–Lithium: Z=3
–Carbon: Z=6
–
•# of
protons and # of neutrons determines mass and nuclear
properties
–Same element (same Z) but different # of neutrons Þ isotope of same element
–Isotopes behave same chemically, but have different
nuclear properties
– 1H =
1 proton, 0 neutrons (regular hydrogen)
– 2H =
1 proton, 1 neutron (deuterium)
– 3H =
1 proton, 2 neutrons (tritium)
–4He= 2 protons, 2 neutrons (regular helium)
–12C = 6 protons, 6 neutrons (regular carbon) 14C = ???