Do different isotopes of the same element bond differently?

So, at the most basic level, the main difference is the energies of the bonds themselves, especially the vibrational energies. Since isotopes are either slightly larger or smaller than the standard atom, bonds to them vibrate at slightly different energies then they would if it were to a standard atom, and this changes the energy of the bond, and makes a difference in terms of cleavage and formation energies. This can actually be fantastically useful in determining chemical mechanisms, and is known as the ‘kinetic isotope effect’, usually primary and secondary isotope effects.

Hydrogen is, naturally, the one that is used most often in these types of experiments, as the isotopes are essentially double and triple the mass of the standard atom, but these effects are still seen for heavier atoms, though you naturally need better and better equipment to tell the difference.

Yes, a Ca^-2 is showing that it has to more electrons that normal so it could bond with C and satisfy the octet. 2Ca normal with carbon would satisfy octet

@SaveTheRhinos Those aren’t the sort of isotopes that I was talking about. Two different isotopes of a specific element are two forms of the element that have a different number of neutrons. This does not affect the number of protons or electrons.

The Wikipedia article on isotope discusses the kinetic isotope effect mentioned above by @BhacSsylan. ”...heavier isotopes tend to react somewhat more slowly than lighter isotopes of the same element.”

The same article also notes that ”...isotopologues will have different sets of vibrational modes. Since vibrational modes allow a molecule to absorb photons of corresponding energies, isotopologues have different optical properties in the infrared range.”

Otherwise I don’t think there’s any chemical difference. Electron orbitals, which determine chemical bonding properties and atomic size, are indifferent to the mass of the nucleus & depend only on proton number.

Great Question :)