Why atomic hydrogen is more active than molecular hydrogen?
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Atomic hydrogen it has one valence electron, whereas molecular hydrogen has none. In chemistry in order for an element or a molecule to be stable (non - reactive) it must satisfy the Octet Rule, where an atom has 8 valence electrons in its outer shell (or 2 for molecular hydrogen and helium).
So in atomic hydrogen, that atom wants to rid of that lonely electron so it can be stable. Hydrogen is classified in group 1, any element in group 1 is highly reactive, this is due to the lone electrons they all have. Take for example chlorine, it is a group 7 element (halogen), this means it has 7 valence electrons! OH SO CLOSE! IT NEEDS ONE MORE! And can you guess who can give up that electron? Oh yes, hydrogen can. So they will bond together and form hydrogen monochloride (aqueous: hydrochloric acid).
Molecular hydrogen on the other hand is two hydrogen atoms bonded together. They share their two electrons and this satisfies the quantum principle number. It fills the 1s orbital with two electrons and it gives molecular hydrogen the electronic configuration of helium. In this ‘noble gas state’ it is almost impossible to react with anything, as it has satisfied the Octet Rule, however you can with plenty of energy, this is referred to as ionization energy. But thats for another time ;)
So in atomic hydrogen, that atom wants to rid of that lonely electron so it can be stable. Hydrogen is classified in group 1, any element in group 1 is highly reactive, this is due to the lone electrons they all have. Take for example chlorine, it is a group 7 element (halogen), this means it has 7 valence electrons! OH SO CLOSE! IT NEEDS ONE MORE! And can you guess who can give up that electron? Oh yes, hydrogen can. So they will bond together and form hydrogen monochloride (aqueous: hydrochloric acid).
Molecular hydrogen on the other hand is two hydrogen atoms bonded together. They share their two electrons and this satisfies the quantum principle number. It fills the 1s orbital with two electrons and it gives molecular hydrogen the electronic configuration of helium. In this ‘noble gas state’ it is almost impossible to react with anything, as it has satisfied the Octet Rule, however you can with plenty of energy, this is referred to as ionization energy. But thats for another time ;)
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