Question

Name or state the following
Metal with valency one

Answer 1

Hint: valency of any substance is its ability to combine by sharing, donating or gaining electrons. It is determined by the outer electronic configuration or the valence configuration of any element. Metals are the substances found at the extreme left of the periodic table. A valency is the same for the elements in the same group.

Complete answer:
Valency of any element tells us about its capacity to form molecules. This is the combining ability of atoms to form bonds and thus molecules. The valency of any element can be detected in the molecular state when it is bonded with other atoms, or by the valence electronic configuration. The electronic configuration tells the valency by the ability of an atom to complete its octet.
We have been given to name the metal that has valency of one. Metals are the elements that have 1 or 2 electrons in their outer shell. So, metals that will have a valency of 1 will be those having 1 valence electron and the configuration will be $n{{s}^{1}}$.
As we know, metals of the group 1 that are the alkali metals consist of only one electron that they lose to form bonds in a compound and to achieve a stable configuration. These metals have a valency of 1 and these metals are lithium, sodium, potassium, rubidium, cesium and francium.
Hence, group 1 alkali metals that are Li, Na, K, Rb, Cs, and Fr have a valency of 1.

Note:
Due to the presence of 1 electron in their outer shell the group 1 alkali metals are highly reactive. Valency tells the capacity of an atom to bond and it can vary in various molecules with the number of electrons present in the outer shell. Valency does not contain a sign of positive or negative as it is the combining ability.