Why is flourine so reactive? If it is because it has one spare electron space close to the nucleus, why isn't hydrodgen more reactive?

Fluorine has the unique postion of having 9 protons in the nucleus and 9 electrons in the neutral atom. but by accepting and extra electron to have 9 protons and a now 10 electrons and form a negativley charged ion ( -1 charge valence ) which now configures the electrons to filled energy levels similar to the noble gas Neon. So fluorine wants to gain this electron and so its reactivity is very high. The ability to want an electron and keep the electron is referred to the electron affinity and elctronegativity respectfuly of the ion which for fluorine is the highest. So fluroine is reactive.

 

Ag

It's due to effective nuclear charge and the also its small size.

Agaubr, I'm a bit confused. I was under the impression that flourine anions are less stable than bromine, chlorine, or iodine anions simply because the small nucleus does not distribute the charge as well.

 

Thats why its a horrid leaving group (in organic chemistry) in aprotic solvents. However, in a protic solvent, hydrogen bonds can quickly stabilize the small ion, making it a great leaving group.

You're right. Flourine is the most electronegative.

One reason for Fluorine being a poorer leaving group is the bond energy for say C-F bond versus C-Cl or C-Br or C-I isvery much larger meaning it takes more enegry to break the bond.

 

Ag