Periodic Table Information
Periodic Table of Elements- tool used to help us study the composition of matter.
Groups/Families- Vertical Columns
1A-8A= Representative Elements
B Elements= Transitional Metals
-Elements within the same group have similar physical and chemical properties.
Periods- Horizontal Rows
-Period number is equal to the number of energy levels (orbitals) within the atom
of that element.
Metals- left of stair step (excluding H)
Nonmetals- right of the stair step
Metalloids- have properties of both metals and nonmetals
-B, Si, Ge, As, Sb, Te, Po, At
Group 1A- Alkali Metals- most reactive metals, 1 valence electron, readily react with the
halogens (explosive in water)
Group 2A- Alkaline Earth Metals- very reactive, 2 valence electrons, readily reacts with
group 6A metals
Group 7A- Halogens- most reactive nonmetals, react readily with the alkali metals, 7
valence electrons
Group 8A- Noble Gases- very stable, will not react with other elements, 8 valence
electrons (outer energy level is full) Octet Rule
Transitional Metals- can change valence counts (B metals)
Lanthanide Series- rare heavy earth metals
Actinide Series- Synthetic metals, mostly radioactive
14
Si
28.09
14= atomic number
Si= chemical symbol
28.09= atomic mass average
Atomic number = number of protons in the atom of that element
The number of electron equals the number of protons (atoms are always electrically
neutral)
The number of neutrons equals the atomic mass number (round atomic mass average to
whole number) – atomic number.
# of neutrons = atomic mass – atomic number
Proton- positive charged particle located within the nucleus of the atom.
Neutron- particle within nucleus of the atom with no charge.
Electron- negatively charged particle located with the electron cloud (orbiting around the
nucleus within energy levels (shells))
For representative elements (A’s) the valence electron count is equal to the group
number.