How many valence electrons does a nickel atom (Ni) have?
The Correct Answer and Explanation is :
A nickel atom (Ni) has 10 valence electrons.
Explanation:
To understand why nickel has 10 valence electrons, we first need to consider its electron configuration. Nickel (Ni) has an atomic number of 28, meaning it has 28 electrons. The electron configuration for nickel is as follows:
[ \text{Ni: } 1s^2 2s^2 2p^6 3s^2 3p^6 3d^8 4s^2 ]
This configuration shows the distribution of electrons in various energy levels or shells. The key to determining the number of valence electrons is to focus on the electrons in the outermost energy level (the highest principal quantum number).
The outermost shell of a nickel atom is the 4th shell, which contains the 4s^2 electrons. Additionally, there are electrons in the 3d^8 subshell. However, for the purpose of counting valence electrons, we focus on the electrons in the highest energy shell that can participate in bonding.
- 4s^2 contributes 2 valence electrons.
- 3d^8 contributes 8 valence electrons, as these electrons are in the third shell, which is also considered part of the valence shell in transition metals like nickel.
Thus, nickel has a total of 2 (from 4s) + 8 (from 3d) = 10 valence electrons.
This is characteristic of transition metals, which can have more than 8 electrons in their valence shell due to the involvement of d orbitals in bonding. These 10 valence electrons enable nickel to form various types of chemical bonds, such as covalent and metallic bonds, and to exhibit a range of oxidation states, which is a hallmark of transition metals.