Periodic table of Elements

• The modern periodic table that we know today is arranged based on atomic number
• The rows in the table are called periods
• The columns are known as groups or families
• Elements in groups 1, 2, and 3-17 are the representative elements or the main group elements. 
•  group 1 is known as the alkali metals
• alkali metals. Elements under this family are highly reactive and possess a single electron in their outermost shell. As a result, these elements readily lose one electron to form ions with a +1 charge. 
• Group 2, on the other hand, is known as alkaline earth metals. Elements under this family have two electrons in their valence shell which they readily lose to form cations with +2 charges.
• Together with the alkali metals, groups 1 and 2 (except H and Be) form strong inorganic bases when bonded with hydroxide ions. Furthermore, these two groups are sometimes referred to as the s block elements.
• Group 18 (noble gases) have filled p subshells (except He). Aside from helium, all members of the group have 8 electrons in their valence shell. As a result, noble gases are chemically inert. They are also colorless, although ionizing them may cause these gases to emit bright colors. This is why noble gases (except Rn) are commonly used in neon signs.
• Groups 3-12 comprise the transition metals. Elements belonging to these groups are generally characterized by partially filled d subshells or those which can give rise to cations with an incomplete d subshell. Because of this, transition metals are sometimes called the d block elements.