for o level it was enough to write H-O-O-H
kinda OK for Dalton 1804 - hydrogen can bond with one other atom, and oxygen with two.
then further along a chemistry course, you wonder if they are strung along or whether the atoms are differently place
and that is where Mama's diagram comes in useful
O-O is in the plance of the page - the crossed bond is into the page and the black thick one is out of the page
further along you wonder if the black lines H-O-O-H are all the same energy - they arent. o-o is stronger than H-O and when broken gives off energy - bond energy and that explains which H2O2 will product oxygen easily and erm water wont
it also explains why I wont go near the explosive Mother of Satan - (triacteone peroxide) - full of O-O bonds just waiting to off. BANG! No wonder bombers spontaneously combust
Thanks, I can see how water, (H2 O) is 2 atoms of hydrogen and 1 atom of oxygen, making a 3 part, 2 to 1 molecule - what I'm wondering (and I'm sure it's a dumb question) what is the difference from 1 atom each of hydrogen and oxygen, why two of each?
My simple mind tells me that two teaspoons each of salt and sugar tastes, and is, the same as one teaspoon of each, it's just half the quantity.
Bear with me please, I have my reasons for asking :0)
Well, that's chemistry for you.
Water is very stable...H2O is a perfectly "balanced" stable molecule.
But, it can be made to accept another oxygen atom, making it hydrogen PERoxide...but this is quite unstable - kept in a dark bottle and kept cool it very slowly loses the extra oxygen atom. In bright light and warm conditions, it decomposes more quickly. The ability to lose the extra oxygen atom makes it a good oxidising-agent...hence, it's bleaching ability.
You are aware that atoms are comprise a central nucleus with electrons whizzing round it. These electrons are in fixed orbits called shells, with differing numbers in each orbit - max 2 in the inner orbit, then 8, then 8 again etc. For a given element the number of electrons in the outer orbit determines its valency which defines how it combines with other elements. Hydrogen has valency =1, oxygen has valency =2; think of them as hands available to hold the hand of another element. Oxygen can hold hands with 2 hydrogen atoms and then both will have their hands full. If an oxygen combines with 1 hydrogen it has a spare hand and becomes an OH molecule with a valency of 1. Because they don't like having empty hands, if another OH molecule comes along it will combine with the first one to form H2O2 with each oxygen atom holding hands with 1 hydrogen and the other oxygen. Now all atoms have all their hands full and they're happy.
P.S. So of the two elements, hydrogen is the more, can I say, 'dominant', and the oxygen is 'fugitive'?
If I get you right, left to stand open and in sunlight, hydrogen peroxide will turn into water?
Sorry Khandro, it's almost 60 years since I last studied chemistry and you last question is taking me beyond my memory. Perhaps ginge or Peter will come back and explain that bit for you.
yes it will - ( go off if left in sunlight ) that is why it is stored in brown bottles
I am no chemist - there is a professor of chemistry knocking around - I dont know if he still posts - some intellects give up faced with the invincible ignorance.
what was the supplementary question ? why does H2O2 exist ? because it can I suppose ....
You might well call me Someone Who Knows, Peter but having spent the last few minutes thinking about how to explain this, I'm unable to do so.
The reason for this is that firstly, fairly complex mathematical symbols and formulae are needed to put this down in writing and there are no means to do so on AB. Secondly, each step assumes an understanding of the previous step and I don't think it's possible to do so without a good understanding of thermodynamics as well as the maths - I can't explain as I go along. Quickly jotting down how hydrogen peroxide photolysis occurs has just consumed six A4 sheets in my notepad.
On top of this, the thermodynamics of the four key steps, namely light absorption initiation, propagation, termination and water regeneration require knowledge of quantum yield to be understood.
Sit in front of me in a lecture theatre and I'll knock it all out in front of you on the blackboard (Chalk remains my favourite medium!). However, it can't be done on AB. Apologies if it sounds like a cop-out.
Happy New Year Bazile. I did a bit of stargazing in my youth but nowadays, I leave astronomy and the universe to others - I find it hard enough to get around the adventures of Captain Picard and his crew!
Thank you prof. and everyone, it is surprising how a simple naive question can need such a complicated answer.
In case anyone is interested, I ask because I'm involved in a project which is vaguely like that of Primo Levi's, 'The Periodic Table' a description of which you can see here;
To anyone who isn't familiar with him, Levi was an Italian Jewish writer, an erstwhile chemist, and a survivor of Auschwitz, I can highly recommend this book.