Question

1. consider group 1 of the periodic table.

describe how the nuclear charge (number of protons in the nucleus)
and number of occupied principal energy levels changes down the
group from top to bottom.
nuclear charge
(number of protons)
number of occupied
principal energy levels
change down group
increases
increases
affect on attraction strength
has a stronger attraction
has a weaker attraction

Explanation:

• Nuclear charge (number of protons): As we move down group 1 of the periodic table, each element has one more proton in its nucleus than the one above it. For example, hydrogen (\(H\)) has 1 proton, lithium (\(Li\)) has 3 protons, sodium (\(Na\)) has 11 protons, etc. An increase in the number of protons (nuclear charge) would, on its own, tend to increase the attraction between the nucleus and the outermost electrons (since protons are positively - charged and electrons are negatively - charged).
• Number of occupied principal energy levels: The principal energy levels (\(n = 1,2,3,\cdots\)) are like "shells" around the nucleus. As we move down group 1, the elements add more energy levels. Hydrogen (\(n = 1\)), lithium (\(n=2\)), sodium (\(n = 3\)), etc. As the number of occupied principal energy levels increases, the outermost electrons are further away from the nucleus. The force of attraction between two charged particles (Coulomb's law \(F=\frac{kq_1q_2}{r^{2}}\), where \(q_1\) is the charge of the nucleus, \(q_2\) is the charge of the electron, and \(r\) is the distance between them) decreases with the square of the distance (\(r\)). So, the increased distance (due to more energy levels) weakens the attraction between the nucleus and the outermost electrons.

Answer:

• Nuclear charge (number of protons): Increases. The effect on attraction strength: Has a stronger attraction (in theory, if only considering the increase in nuclear charge). But in reality, the shielding effect (due to inner - shell electrons) and the increase in distance (from more energy levels) also play a role, but based on the question's requirement to consider the change in nuclear charge alone for this part of the analysis.
• Number of occupied principal energy levels: Increases. The effect on attraction strength: Has a weaker attraction (because the outermost electrons are further from the nucleus).