Potential Energy of atoms and molecules

[Fusilli_Jerry89]

which has more potential energy, a Br2 molecule or two separate bromine atoms? I put the molecule because the fact that it is both attracted and repelled by the charges increases its potential energy. I just want to confirm if I'm right.

 

[geoffjb]

which has more potential energy, a Br2 molecule or two separate bromine atoms? I put the molecule because the fact that it is both attracted and repelled by the charges increases its potential energy. I just want to confirm if I'm right.

The two Br atoms are most stable when they are a certain distance from each other, where electron-electron and proton-proton repulsions are best matched by electron-proton attractions. This distance, known as the bond length, has a lower potential energy than if the atoms were closer together or farther apart.

Consider the following image, obtained from Chemicool.com (used for educational purposes only).

 

[mrjeffy321]

Bromine is a diatomic element.
In its elemental state, Bromine will naturally form a covalent bond with itself to form Br2 as opposed to two Br atoms.
Why does it do this? The simple answer (which can apply to a wide range of physical phenomenon) is that there is a decrease in the free energy when this occurs...Br2 is more stable than 2Br.
Energy is given off when bonds are formed and atoms are always looking for ways to reduce their energy level in order to achieve their most stable states.