When are larger atoms least likely to be reactive?

Answer 1

It's hard to say how far to go with this. But let's think of it intuitively and see what emerges. So atoms react when they're not completely happy with their current selves.

1. If they have too much energy, they try and lose some (energy is released upon bond formation).

2. If they have not filled their valance shell, they will want to fill it.

So conversely, we can see that atoms with very little energy will not react. At ground state (low energy) they are very stable.

And again, conversely, when their valance shell is filled (see; Noble Gases) they are stable and unreactive....inert even!

This is true of molecules, too. Carbon with no bonds has 4 valance e-....meaning 4 are missing to complete the valance shell. So C on it's own would be incredibly reactive, in fact you'll never see it.

But CH4 means both C and H have filled their valance shells and so it's much more stable and unreactive. Of course, CH4 will react with some things but you can see how filling those valance shells has made a big difference to the stability.

So those are the two big points. Other things, like being a solid, increase stability in some ways. Especially if dissociation is required before a further reaction occurs.

Like H2O in solution is constantly converting to and from H+ and OH-. In ice, this doesn't really occur so much....but again, we have a potential temperature argument. So probably a point best ignored as it becomes something of a semantic argument.

Other things such as whether a reaction is symmetry allowed, sterics and conformation can be very important...but again more to do with specific reactivities than general stability.

Answer 2

When its valence orbitals are fully filled.

Answer 3

atom is likely to react when it has a pair of electrons for bonding.............

Answer 4

When they have 8 valence electrons.