To determine which pairs of elements will form polar covalent bonds together, we need to consider the electronegativity differences between the pairs. A bond is considered polar covalent if the electronegativity difference between the two elements is between 0.4 and 2.0.
1. Electronegativity Differences:
- For [tex]\( \text{Na} - \text{F} \)[/tex]: The electronegativity difference is 3.05.
- For [tex]\( \text{H} - \text{H} \)[/tex]: The electronegativity difference is 0.0.
- For [tex]\( \text{H} - \text{F} \)[/tex]: The electronegativity difference is 1.78.
- For [tex]\( \text{N} - \text{F} \)[/tex]: The electronegativity difference is 0.94.
2. Determining Polarity:
- For the [tex]\( \text{Na} - \text{F} \)[/tex] pair, the electronegativity difference is 3.05, which is outside the polar covalent range (0.4 to 2.0).
- For the [tex]\( \text{H} - \text{H} \)[/tex] pair, the electronegativity difference is 0.0, which is less than 0.4, so it is not polar covalent.
- For the [tex]\( \text{H} - \text{F} \)[/tex] pair, the electronegativity difference is 1.78, which is within the range for polar covalent bonds (0.4 to 2.0).
- For the [tex]\( \text{N} - \text{F} \)[/tex] pair, the electronegativity difference is 0.94, which also falls within the range for polar covalent bonds (0.4 to 2.0).
Conclusion:
The pairs that will form polar covalent bonds are:
- [tex]\( \text{H} - \text{F} \)[/tex]
- [tex]\( \text{N} - \text{F} \)[/tex]
