Why is it easier to remove an electron from a sodium (Na) atom than from a magnesium (Mg) atom?

• A. Sodium has a lower ionization energy because its outer electron is in a higher energy level and experiences less effective nuclear charge than magnesium.
• B. Magnesium has a lower ionization energy because it has more protons than sodium.
• C. Magnesium's outer electron is more shielded, making it easier to remove than sodium's.
• D. Sodium has a higher ionization energy because it has fewer electrons than magnesium.

Answer: (A)

Verified step by step guidance

1. Understand that ionization energy is the energy required to remove an electron from an atom in its gaseous state.
2. Recognize that sodium (Na) has an electron configuration of \$1s^2 2s^2 2p^6 3s^1$, meaning its outermost electron is in the 3rd energy level (3s orbital).
3. Magnesium (Mg) has an electron configuration of \$1s^2 2s^2 2p^6 3s^2$, so its outermost electrons are also in the 3rd energy level but it has one more proton in the nucleus than sodium.
4. Consider the concept of effective nuclear charge (\(Z_{eff}\)), which is the net positive charge experienced by an electron after accounting for shielding by inner electrons. Magnesium's higher nuclear charge pulls its outer electrons more strongly, increasing ionization energy.
5. Conclude that because sodium's outer electron is in the same energy level but experiences less effective nuclear charge and less attraction from the nucleus, it requires less energy to remove compared to magnesium.