Question

consider the following 3 sets of protons and electrons. which set has the weakest force of attraction? set a b c number of protons 14 12 16 number of valence electrons 4 2 6 number of shields between the protons and valence electrons 2 2 2

Explanation:

Step1: Recall force - attraction concept

The force of attraction between protons and valence electrons is influenced by the number of protons and the shielding effect. The effective nuclear charge ($Z_{eff}$) experienced by valence electrons is given by $Z_{eff}=Z - S$, where $Z$ is the number of protons and $S$ is the number of shielding electrons. Here, the number of shielding electrons between protons and valence electrons is the same ($S = 2$) for all sets. So, the force of attraction depends on the number of protons and valence - electrons ratio.

Step2: Calculate the ratio for each set

For set A: The number of protons $Z_A=14$ and the number of valence electrons $n_A = 4$. The ratio of protons to valence electrons is $\frac{Z_A}{n_A}=\frac{14}{4}=3.5$.
For set B: The number of protons $Z_B = 12$ and the number of valence electrons $n_B=2$. The ratio of protons to valence electrons is $\frac{Z_B}{n_B}=\frac{12}{2}=6$.
For set C: The number of protons $Z_C=16$ and the number of valence electrons $n_C = 6$. The ratio of protons to valence electrons is $\frac{Z_C}{n_C}=\frac{16}{6}\approx2.67$.

Step3: Determine the set with the weakest force

The lower the ratio of protons to valence electrons (when the shielding is the same), the weaker the force of attraction. Since set C has the lowest ratio of protons to valence electrons among the three sets, it has the weakest force of attraction.

Answer:

C