The Alkali Metals
The alkali metals are the group IA (1) elements in the table.
They form hydroxides which are strongly basic (i.e., potassium hydroxide--KOH), hence the term "alkaline" being applied in basic substances.
They have a very high metallic behavior and are good reducing agents.
The alkali metals crystallize with a body-centered cubic lattice in which the points are occupied by +1 ions.
The sea of valence electrons throughout the entire lattice can wander throughout the metal and produce high electrical conductivity.
The high electrical conductivity is accompanied by a high heat conductivity.
Their high luster is due to the highly mobile electrons of the lattice.
Light beams hit the electrons into oscillations, reflecting back electromagnetic energy as light.
The softness, malleability, and ductility of the metals are due to the nature of the forces holding the lattice together.
Since there is no net force or attraction between the ions, they can be moved from one lattice site to another.
The Alkaline Earth Metals
The alkaline earth metals are the group IIA (2) elements in the table.
They are called alkaline earth metals because the "earths" of this group, lime (CaO), and magnesia (MgO), give alkaline reactions.
They have good metallic properties, including conductivity, reduction ability, luster, softness, malleability, and ductility, but not as well as the alkali metals.
There ions have an oxidation state of +2.
Like alkali metals, they form soluble sulfides, but unlike them, they
form insoluble carbonates (calcium carbonate -- CaCO3 -- in hard water).
The Post-Transition Metals
The post-transition metals include the lower elements of group IIIA (13), IVA (14), and VA (15), arranged in a staircase like fashion.
There properties have the same relationship to the alkaline earth metals as the alkaline earth metals have to the alkali metals.
The metals in group IIIA (13) are aluminum, gallium, indium, and thallium.
The metals in group IVA (14) are tin and lead, and the metal in group VA (15) is bismuth.
As you go up the group, their metallic character gets less and less.
For example: boron, which is above aluminum in group IIIA (13), is not a metal but a metalloid.