Question

The valence shell of element X contains $2$electrons in a $5\mathrm{s}$sub-shell. Below that shell, element X has a partially filled $4\mathrm{d}$subshell. What type of element is X?

Answer 1

Shell:

• Electrons, inside an atom, follow a certain pathway. This pathway is known as a shell.
• Shells have energy levels and the energy of each shell is constant.
• These shells are named K, L, M, N, etc.

Subshell:

• A subshell is a division of an electron shell and each subshell has its shape.
• In each subshell, electrons are grouped into orbitals, regions of space within an atom where the specific electrons are most likely to be found.
• The first shell contains only one subshell which is '$\mathrm{s}$‘ and the second subshell contains two subshells ’$\mathrm{s}$‘ and ’$\mathrm{p}$' and so on.

Analyzation of the problem:

• The element X consists of two electrons in the subshell$5\mathrm{s}$.
• This means $5\mathrm{s}$ orbital is completely filled.
• The element X is of the fifth principal shell, which means it lies in the fifth period.
• The element X has a partially filled$4\mathrm{d}$ and hence the element should be of a fifth-period transition element.

Hence, element X is the 5th-period transition element.