Phosphorus has a __________ ionization energy than magnesium because __________. (LO 6.5, 6.6) (a) larger; the electron in phosphorus is in a higher n level than the electron in magnesium (b) larger; the electron in phosphorus has a higher Zeff than the electron in magnesium (c) smaller; the electron in phosphorus is in a lower n level than the electron in magnesium (d) smaller; the electron in phosphorus has a lower Zeff than the electron in magnesium

Verified step by step guidance

1. Step 1: Understand the concept of ionization energy, which is the energy required to remove an electron from an atom in the gaseous state.
2. Step 2: Recall that effective nuclear charge (Zeff) is the net positive charge experienced by an electron in a multi-electron atom, influencing ionization energy.
3. Step 3: Consider the periodic trends: Ionization energy generally increases across a period from left to right due to increasing Zeff and decreases down a group due to increasing atomic size.
4. Step 4: Compare the positions of phosphorus and magnesium on the periodic table. Phosphorus is to the right of magnesium in the same period, suggesting a higher Zeff for phosphorus.
5. Step 5: Evaluate the options: Since phosphorus has a higher Zeff than magnesium, it will have a larger ionization energy, making option (b) the correct choice.

Key Concepts

Ionization Energy

Ionization energy is the energy required to remove an electron from an atom in its gaseous state. It generally increases across a period due to increasing nuclear charge, which attracts electrons more strongly, and decreases down a group as electrons are added to higher energy levels, which are further from the nucleus.

Effective Nuclear Charge (Zeff)

Effective nuclear charge (Zeff) is the net positive charge experienced by an electron in a multi-electron atom. It accounts for the shielding effect of inner electrons, meaning that outer electrons feel a reduced attraction to the nucleus. A higher Zeff leads to a stronger attraction between the nucleus and the outer electrons, resulting in higher ionization energy.

Principal Quantum Number (n)

The principal quantum number (n) indicates the main energy level occupied by an electron in an atom. As n increases, the electron is located further from the nucleus, which generally results in a weaker attraction to the nucleus and lower ionization energy. Thus, electrons in higher n levels are easier to remove compared to those in lower n levels.