The groups
Alkali metals
The alkali metals, found in group 1 of the periodic table, are highly reactive metals that do not occur freely in nature. These metals have only one electron in their outer shell. Therefore, they are ready to lose that one electron in ionic bonding with other elements. As with all metals, the alkali metals are malleable, ductile, and are good conductors of heat and electricity. The alkali metals are softer than most other metals.
alkali earth metals
The alkaline earth elements are metallic elements found in the second group of the periodic table. All alkaline earth elements have an electron configuration number of +2, making them very reactive.
transition metals
The transition elements are both ductile and malleable, and conduct electricity and heat.
Lanthanides
Noble gases
halogens
metalloids
non metals
Non-metals are the elements in groups 14-16 of the periodic table. Non-metals are not able to conduct electricity or heat very well. As opposed to metals, non-metallic elements are very brittle. The non-metals can be gases, such as oxygen and solids, such as carbon. The non-metals have no metallic luster, and do not reflect light. They have oxidation numbers of ±4, -3, and -2.
A contrast in elements: sodium and argon
Being two very different elements, Sodium and Argon lie on the opposite sides of the periodic table. On one hand, Sodium is part of the alkali metals and is extremely reactive because of the one electron on its outer shell. Its melting point is 96 degrees Celsius, and is therefore a solid in room temperature, while Argon’s melting point is -189.4 degrees Celsius, making it a gas in room temperature. Both elements have different electron configurations (hence why they are on opposite sides of the periodic table) and react very differently. On the other hand of Sodium is Argon, which, as a part of the noble gas group, has its valence shell full of electrons and does not find the need to react with anything. This makes it a very stable gas. Despite this, however, it can still be seen that both elements lie on the same period, and can both be found in common objects.