Question

Which of the following atoms has seven valence electrons?

chlorine (Cl)
nitrogen (N)
manganese (Mn)
oxygen (O)

Answer 1

Chlorine (CI) has seven valence electron. It is one of the most active non metals.

Answer 2

Answer: Chlorine and manganese have seven valence electrons.

Step-by-step explanation:

Valence electrons are defined as the electrons which are present in outermost shell of an element. It is determined by the electronic configuration of an element.

For the given options:

Option 1: Chlorine (Cl)

The atomic number of this element is 17.

Electronic configuration of Cl:
`[Ne]3s^23p^5`

This element has 7 electrons in the outermost shell and thus it has 7 valence electrons.

Option 2: Nitrogen (N)

The atomic number of this element is 7.

Electronic configuration of N:
`[He]2s^22p^3`

This element has 5 electrons in the outermost shell and thus it has 5 valence electrons.

Option 3: Manganese (Mn)

The atomic number of this element is 25.

Electronic configuration of Mn:
`[Ar]4s^23d^5`

In transition elements, the number of ns and (n-1) d electrons are considered as valence electrons. Thus, it has 7 valence electrons.

Option 4: Oxygen (O)

The atomic number of this element is 8.

Electronic configuration of O:
`[He]2s^22p^4`

This element has 6 electrons in the outermost shell and thus it has 6 valence electrons.

From the above information, chlorine and manganese have seven valence electrons.