Question

Suppose the mass number of an element is$27$. Find valence shell of this element, if it has $14$ neutrons:
A. L
B. K
C. N
D. M

Answer 1

In order to answer this question first we know about the distribution of electrons on valence shells. According to electronic configuration, we calculate shell by using this formula: $2{{n}^{2}}$

Complete step-by-step solution:
As indicated by the hypothesis of Neils Bohr, "electrons spin around the focal point of an atom in an anticipated pathway named orbits". The portrayal of the orbit is finished by letters and numbers like K, L, M, N, O…furthermore, $1,2,3,4$… .individually.
The most extreme number of electrons present in a specific shell is determined by the equation
$2{{n}^{2}}$, where "n" addresses the shell number. For example, K shell is the primary shell and it can hold up
to $2{{\left( 1 \right)}^{2}}=2$electrons. Additionally, L shell is the subsequent shell and it can hold up to $2{{\left( 2 \right)}^{2}}=8$
electrons. This equation assists with figuring the most extreme number of electrons that a circle can oblige.
The greatest ability to hold electrons in the furthest shell is$8$.
The electrons will fill the inward shells before the external shells. First electrons will fill the K-shell and afterward L shell, etc. Accordingly, electronic design of components follows a rising request.
In this question element have neutron $14$and mass number is $27$
Therefore, no of electron

& \Rightarrow \left( Z-n \right) \\\ & \Rightarrow (27-14)=13 \\\ \end{aligned}$$ So, the electron distribution according to shells is$$2\left( K \right),8\left( L \right),3\left( M \right)$$. **Therefore, option D. M is the right answer.** **Note:** Elements which are present in the same group in the periodic table having the same configuration. As per the laws of quantum mechanics, for frameworks with only one electron, a degree of energy is related with every electron design and in specific conditions, electrons can move starting with one arrangement then onto the next by the discharge or retention of a quantum of energy, as a photon.