Question

1. effective nuclear charge is the relative force of attraction experience by a valence electron towards the nucleus of an atom. it includes both attractive forces and repulsive forces. using fundamental charge values (ie. an electron is -1, each proton is +1 & the nuclear charge is the sum of all protons) calculate the effective nuclear charge experienced by a valence electron in each atom.

Explanation:

Step1: Recall effective nuclear charge formula

The effective nuclear charge ($Z_{eff}$) is calculated as $Z_{eff}=Z - S$, where $Z$ is the atomic number (number of protons) and $S$ is the shielding constant. For a simple approximation in a one - electron atom or for the outermost electron in a multi - electron atom, we consider the inner electrons as shielding the outer electron from the full nuclear charge. In a simple case, if we assume that the inner electrons completely shield the outer electron from the nuclear charge, and there are no other complicating factors. For example, in a sodium atom ($Na$) with atomic number $Z = 11$. The electron configuration is $1s^{2}2s^{2}2p^{6}3s^{1}$. The 10 inner electrons ($1s^{2}2s^{2}2p^{6}$) shield the 3s valence electron. So, $Z_{eff}=11 - 10=1$. But in general, we need to know the electron configuration of the atom.
Let's assume a general atom with atomic number $Z$ and $n$ inner electrons that shield the valence electron.
$Z_{eff}=Z - n$

However, since no specific atom is given in the problem statement, we can't calculate a numerical value. But the general formula for calculating the effective nuclear charge of a valence electron is $Z_{eff}=Z - S$, where $S$ is the shielding constant which can be estimated based on the electron - shell structure of the atom.

Answer:

The formula for calculating the effective nuclear charge experienced by a valence electron is $Z_{eff}=Z - S$, where $Z$ is the atomic number (number of protons) and $S$ is the shielding constant. Without a specific atom given, a numerical value can't be determined.