Question

Explain why alkali metals always form +1 ions?

Answer 1

You should know that group 1 elements are known as alkali metals. Here, in the question it is asked why alkali metals always form +1 ions and to answer this, refer to the general valence electron configuration of alkali metals.

Complete answer:
Group 1 of the periodic table consists of the elements: lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs), and francium (Fr). These elements are collectively known as the alkali metals. These are so called because they form hydroxides in reaction with water, which are strongly alkaline in nature.
Group 1 of the periodic table belongs to s-block and general electronic configuration of s-block elements is [noble gas] $n{s^1}$ for alkali metals. Thus, all the alkali metals have one valence electron, $n{s^1}$ outside the noble gas core. They readily lose this one electron to attain more stable noble gas configuration and give monovalent ${M^ + }$ ions, where M is any alkali metal. Hence, we can say that alkali metals always form +1 ions.
Additional information: The alkali metals tarnish in air due to formation of their oxides which in turn react with the present moisture in the atmosphere to form hydroxides. They burn vigorously in atmospheric oxygen to form oxides.

Note:
It should be noted that alkali metals are never found in free state in nature because they readily lose their valence electrons to give monovalent ${M^ + }$ ions. Also, they are highly reactive because of their large size and low ionization enthalpies. Because of their high reactivity towards air and water, they are generally kept in kerosene oil.