To determine which pair of atoms has the highest electronegativity difference, we first need to calculate the absolute differences in electronegativity for each pair listed.
Given the electronegativity values:
- Calcium (Ca) = 1.0
- Carbon (C) = 2.55
- Fluorine (F) = 4.0
- Hydrogen (H) = 2.2
- Phosphorus (P) = 2.19
- Sodium (Na) = 0.93
Let's compute the electronegativity differences for each specified pair:
1. Na and F:
[tex]\[
|\chi_{\text{Na}} - \chi_{\text{F}}| = |0.93 - 4.0| = 3.07
\][/tex]
2. Ca and F:
[tex]\[
|\chi_{\text{Ca}} - \chi_{\text{F}}| = |1.0 - 4.0| = 3.0
\][/tex]
3. H and F:
[tex]\[
|\chi_{\text{H}} - \chi_{\text{F}}| = |2.2 - 4.0| = 1.8
\][/tex]
4. C and F:
[tex]\[
|\chi_{\text{C}} - \chi_{\text{F}}| = |2.55 - 4.0| = 1.45
\][/tex]
5. F and F (this would always be zero since it's the same element):
[tex]\[
|\chi_{\text{F}} - \chi_{\text{F}}| = |4.0 - 4.0| = 0.0
\][/tex]
Now, let's compare the absolute differences:
- Na - F: 3.07
- Ca - F: 3.0
- H - F: 1.8
- C - F: 1.45
- F - F: 0.0
Among these, the highest electronegativity difference is clearly between sodium (Na) and fluorine (F), with a difference of 3.07.
Thus, the pair of atoms with the highest electronegativity difference is:
[tex]\[
\boxed{Na - F}
\][/tex]
