How do we know which element is diatomic?

Question

for .i.e F is diatomic when by itself, but how do we know that which one is?

Answer 1

well some gasses naturally exist in diatomic form, like O2, Br2, Cl2, N2, H2...

they would be unstable if the two atoms seperated

Answer 2

You have to remember that the elements H, N, O, and the halogens (F, Cl, Br, I) are diatomic (in all three phases, too.)

In addition, all elements which are not found at the right end of a block on the Periodic table (s-block, p-block, d-block, f-block) are in principle capable of forming diatomic molecules in the gas phase. For example, phosphorus forms P2 molecules in the gas phase at high temperatures (at lower temperatures it is in tetrahedral P4 molecules.) However, for certain reasons this may not be achieved. For example, tungsten boils at 5800 K, and the entropy factor is so influential at this high temperature that tungsten may go directly to atoms in the gas phase (and not W2 molecules) - perhaps the scientific literature has some data.