Question

which of the following has a larger radius than zinc
magnesium
gallium
strontium
aluminum

Explanation:

To determine which element has a larger atomic radius than Zinc (Zn), we use the trends of atomic radius in the periodic table:

• Atomic Radius Trend 1 (Same Group): Atomic radius increases as we move down a group because each subsequent element has an additional electron shell.
• Atomic Radius Trend 2 (Same Period): Atomic radius decreases as we move from left to right across a period because the effective nuclear charge increases, pulling electrons closer to the nucleus.

Step 1: Analyze Magnesium (Mg)

Magnesium is in Group 2, Period 3. Zinc is in Group 12, Period 4.

• Mg is in a period above Zn (Period 3 vs. Period 4) and in a group to the left. But when comparing, Mg has fewer electron shells (3) than Zn (4). So, the atomic radius of Mg ($r_{\text{Mg}}$) is smaller than Zn ($r_{\text{Zn}}$) because the number of electron shells is a major factor. So, $r_{\text{Mg}} < r_{\text{Zn}}$.

Step 2: Analyze Gallium (Ga)

Gallium is in Group 13, Period 4 (same period as Zn).

• As we move from left to right across a period (from Zn in Group 12 to Ga in Group 13), the atomic radius decreases due to increasing effective nuclear charge. So, $r_{\text{Ga}} < r_{\text{Zn}}$.

Step 3: Analyze Strontium (Sr)

Strontium is in Group 2, Period 5.

• Sr is in a group (Group 2) and a period (Period 5) below Zn (Group 12, Period 4). Moving down a group, the number of electron shells increases (Sr has 5 shells, Zn has 4 shells). Even though Sr is in a different group, the increase in electron shells dominates, so the atomic radius of Sr is larger than Zn. So, $r_{\text{Sr}} > r_{\text{Zn}}$.

Step 4: Analyze Aluminum (Al)

Aluminum is in Group 13, Period 3.

• Al is in a period above Zn (Period 3 vs. Period 4) and has fewer electron shells (3) than Zn (4). So, $r_{\text{Al}} < r_{\text{Zn}}$.

Answer:

Strontium (the option with "Strontium" text) has a larger radius than Zinc.