Why is one covalent bond stronger than other? AS chemistry

In bonds of the same type i.e. single covalent bonds, double bonds, triple bonds etc there will only be a relatively small difference in the bond enthalpy (the energy needed to break the bond). This is due to electronegativity differences between the two atoms involved, so H-F will be a slightly stronger bond than C-H because hydrogen is not very electronegative and flourine is the most electronegative atom of the element.

The main differences in covalent bond strengths depend on how many electron pairs are shared between the two atoms. A double bond is stronger than a single bond, and likewise a triple bond is even stronger than both a single and double covalent bond.

Ohhh, thank you that really cleared it up. Also, I just saw in my textbook that the bond enthalpy for H-H is stronger than the bond enthalpy for C-H, do you know why that is?

Ohhh, thank you that really cleared it up. Also, I just saw in my textbook that the bond enthalpy for H-H is stronger than the bond enthalpy for C-H, do you know why that is?

They're both single bonds, so they're similar in that respect, however the hydrogen atom is much much smaller than the carbon atom, and so has a smaller covalent radius and therefore there's much greater attraction at this small distance.

There are more factors that can influence the strength of a bond, way beyond the scope of the AS/A level course. Atomic radii, the polarity, the electronegativity and more, but you really don't need to worry about all of that stuff, just about the order of triple as the strongest, then double, then single. But in the H-H bond, both H atoms are very small, with only one proton and one electron, meaning there is very little effect of shielding between the two atoms, and so the bond is stable, also because of hydrogen's very low electronegativity. In real life as it were, a single C-H bond doesn't exist in a molecule, whereas of course the H-H bond does, so it's likely that the C-H bond enthalpy value is an average of common or all of the C-H bonds found in molecules.