Question

Elements with valency 1 are

• A. Always metals
• B. Always metalloids
• C. Either metals or non-metals
• D. Always non-metals

Answer 1

The correct option is C

Either metals or non-metals

The explanation for the correct option

Valency is defined as the combining power of an element.

option (C): Metal: Metal is any of a class of substances characterized by high electrical and thermal conductivity as well as by malleability, ductility, and high reflectivity of light.

• Metal donates the electron.
• Alkali group metals or group $1$ metals have one electron in their valence shell and hence they will lose these electrons to attain noble gas configuration. They have valency:$1$.
• Example:sodium has atomic number 11.Electronic configuration:$2,8,1$Hence valency=1..

Nonmetal is any of a class of substances characterized by high electrical and thermal conductivity as well as by malleability, ductility, and high reflectivity of light.

• Halogen group have one electron less than noble gas configuration and hence they have valency $1$
• Example:fluorine has atomic number 9.Electronic configuration:$2,7$.Hence valency=$1$
• Nonmetal accepts the electron.
• Metals and non-metals both can have valency $1$.

The explanation for the incorrect option:

Options A and D:

As option (C) Either metals or non-metals is correct, so always metals and always non-metals are not the correct options.

Option (B):

• Elements with valency $1$ for example sodium has atomic number 11. Electronic configuration$2,8,1$. It is easier to lose the outermost electron and become stable and it is metal while for example chlorine with an electronic configuration $2,8,7$ it accepts one electron to form $C{l}^{-}$ and attain a stable configuration. It is a non-metal.
• Hence elements with valency $1$can be metals or nonmetals but not metalloids.
• The valence shell of metalloids contains $3,4,5,6$ as elements starting from period $2to5$.

Therefore, option (C) is correct.