period: a row of the periodic table. Properties of the elements are periodic, meaning that they repeat after a specific interval. Elements in the same period have their highest energy electrons in the same principal energy level.
group (family): a column of the periodic table. Elements in the same group have the same number of valence electrons, and therefore have similar chemical and physical properties.
metals: elements to the left of and below the “stairstep line.”
non-metals: elements to the right of and above the “stairstep line.”
metalloids: most of the elements that touch the “stairstep line”. (All except for Al and Po).
metals:
· shiny
· high density
· good conductors of heat & electricity
· malleable & ductile (can be reshaped by hammering, bending and stretching)
· high melting & boiling points
· most have 3 or fewer valence electrons
· tend to form positive ions
non-metals:
· dull
· low density
· poor conductors of heat & electricity
· brittle
· low melting & boiling points
· most have 4 or more valence electrons
· tend to form negative ions
metalloids: can have properties “in between” or can have some properties like metals and others like non-metals.
alkali metals: elements in group IA of the periodic table.
· 1 valence electron (form +1 ions)
· very reactive
· soft
· very high melting & boiling points
· ions are soluble in water
alkaline earth metals: elements in group IIA of the periodic table.
· 2 valence electrons (form +2 ions)
· reactive, though not as much as group I metals
· very high melting & boiling points
· ions are not soluble in water
transition metals: elements in the center section of the periodic table.
· have a partially-filled d sub-level
· form colored ions when dissolved in water
· officially have 2 valence electrons, but can shift electrons into and out of s and d sub-levels. Often form more than one kind of ion.
· most are shiny, hard metals with high melting & boiling points
inner transition metals: elements in the “f block” of the periodic table.
· are part of the transition metals
· have a partially-filled f sub-level
· officially have 2 valence electrons, but can shift electrons between s, d, and f sub-levels. Usually form ions with +3 charges.
· are rare
halogens: elements in group VIIA of the periodic table.
· 7 valence electrons (form −1 ions)
· reactive
· diatomic (atoms in pairs) in their natural state: F2, Cl2, Br2, I2
· low melting & boiling points. (F & Cl are gases at room temp; Br is a liquid, and I is a solid, but will melt in your hand.)
· form salts that are soluble in water (except for fluorine—flouoride salts are not soluble in water.)
noble gases: elements in group VIIIA of the periodic table.
· 8 valence electrons (except for He which has 2)—full valence shells
· do not form ions
· do not react with other compounds
· gases
· extremely low melting & boiling points. (In fact, helium cannot be made into a solid even at absolute zero, except at extremely high pressures.)