Given the electronegativities calcium 1 point 0, fluorine 4 point 0, hydrogen 2 point 2 and sodium 0 point 93, which pair of atoms has the highest electronegativity difference?

Introduction / Context:
Electronegativity is a measure of how strongly an atom attracts shared electrons in a chemical bond. The difference in electronegativity between two bonding atoms helps predict whether a bond will be nonpolar covalent, polar covalent or ionic. Larger differences usually indicate more ionic character. This question gives electronegativity values for calcium, fluorine, hydrogen and sodium and asks you to identify the pair of atoms that has the highest electronegativity difference.

Given Data / Assumptions:

• Electronegativity of calcium is 1 point 0.
• Electronegativity of fluorine is 4 point 0.
• Electronegativity of hydrogen is 2 point 2.
• Electronegativity of sodium is 0 point 93.
• We assume simple subtraction of values to find electronegativity differences.

Concept / Approach:
To find the pair with the highest difference, we subtract the electronegativity values for each given pair and compare the results. The pair with the largest numerical difference will have the most polar or most ionic bond character. Pairs of identical atoms, such as F and F, will have a difference of zero. We therefore expect that a metal with very low electronegativity combined with fluorine, the most electronegative element, will yield the highest difference.

Step-by-Step Solution:
Step 1: For F and F, difference equals 4 point 0 minus 4 point 0, which is 0. Step 2: For Ca and F, difference equals 4 point 0 minus 1 point 0, which is 3 point 0. Step 3: For H and F, difference equals 4 point 0 minus 2 point 2, which is 1 point 8. Step 4: For Na and F, difference equals 4 point 0 minus 0 point 93, which is 3 point 07. Step 5: Compare the values and see that 3 point 07 for Na and F is the highest electronegativity difference.

Verification / Alternative check:
We can verify our result qualitatively. Sodium is a highly electropositive metal with very low electronegativity, while fluorine is the most electronegative element in the periodic table. The bond between sodium and fluorine in sodium fluoride is strongly ionic, which is consistent with a very large electronegativity difference. Calcium is also a metal with low electronegativity, but it is slightly higher than that of sodium, so the calcium fluorine difference is a bit smaller. This qualitative reasoning matches the numerical calculation and confirms that sodium and fluorine have the greatest difference.

Why Other Options Are Wrong:
The pair F and F has no difference in electronegativity because it consists of identical atoms.
Calcium and fluorine have a large difference, but it is smaller than the sodium fluorine difference.
Hydrogen and fluorine have a moderate difference that leads to a polar covalent bond but not the largest difference among the given pairs.
The pair hydrogen and sodium shows a difference between a non metal and a metal, but this difference is still less than that between sodium and fluorine.

Common Pitfalls:
Students sometimes choose calcium and fluorine due to the clear contrast between a metal and an extremely electronegative non metal, without carefully calculating the exact values. Another pitfall is to overlook that sodium has slightly lower electronegativity than calcium, making the sodium fluorine difference slightly larger. Always perform the simple subtraction for all options instead of relying purely on intuition.

Final Answer:
The pair of atoms with the highest electronegativity difference is sodium and fluorine, that is Na and F.