Hydrogen, literally meaning “generated from water” (2 H2 O –> 2 H2 + O2) is the simplest and the most abundant of all atoms in this universe (74% of all matter).
They fuse together (nuclear fusion) and make all the stars shine. This makes it the basic raw material of all the other ‘matter’: element, compound molecules and life in general.
More on that awesomeness later. Let’s first see it’s chemistry. Trust me it’s no less wonderful!
Hydrogen atom has one proton and one electron.
When two hydrogen atoms bond with each other, they form an explosive gas H2. The ‘explosion’ in the air is basically oxidation of H2 by oxygen gas, and the product being water and heat.
- But why did the heat come out ?
Heat coming out is an indication that some excess energy in the system has finally found it’s ‘release’ in the form of heat, so the product formed will have lesser potential energy than the reactant. Well water is pretty darn stable.
- What makes water stable ?
Water is a polar compound with polar bonds. As in, oxygen and hydrogen in them don’t share electrons equally. Oxygen pulls electrons away from hydrogen, thus creating a small ‘+ive’ charge on hydrogen atoms and a small ‘-ive’ charge onto itself. Not only is the bond polar, even the whole compound retains ‘polarity’ in electric charge. Since oxygen itself has two pairs of its own electrons to accommodate, the hydrogen bonded to it are not exactly opposite to each other, thus making the entire molecule polar.
- Why oxygen pull electrons from hydrogen in the water molecule ? Who else can also do that ?
Nitrogen, Oxygen and Fluorine have 3, 2 and 1 vacant spaces in the in the 2nd shell p-orbital. 2p is pretty close to the nucleus having 7,8, and 9 protons for N, O and F respectively. So whenever N, O and F bonds with other elements, especially metals or metal-like like atoms which are ready to give electrons away, they pull the electrons more than their ‘fair’ equal share.
- Did oxygen pull the electron or hydrogen gave it away to nitrogen, oxygen or fluorine seeing their peculiar desperation to bond and still keep electrons towards themselves? What’s in it for hydrogen?
Well, whether oxygen pulled it or hydrogen gave the electron away can be a matter of debate, but one can surely say that the atoms now got close to each other due to the attraction between the opposite charges. Now H and O are closer to each other and together happily, so it must have been a mutual decision.
In fact it makes hydrogen so happy that, for example breaking oxygen and hydrogen apart from water would take quite some energy (241 kJ/mol for water vapour and 285 kJ/mol for liquid water).
That’s hydrogen bond for you;
making water’s property unique, uniquely bonding with each other;
making it’s liquid state quite stable over a good range of temperature and pressure.
And luckily, our earth seems to be situated at the ‘Goldilock Zone’ from the Sun. (Sun again is where hydrogen is busy fusing and forming all other elements, the star-stuff).
Not only that, the earth thankfully has the right atmosphere (so far, unless we mess around too much), so unique that water in it’s surface at 273 to 323 K is in a liquid medium. A stable ‘polar’ solvent like water serves as a perfect breeding ground for formation and transformation of millions of molecules, ions, ligands and metal complexes, including all those involved playing ‘life/death’.
Hydrogen is an integral part of all living beings known so far; not only just flowing in them as water molecules. It forms myriads of molecules by bonding with carbon thereby creating a huge family of hydrocarbons. Branching out from these hydrocarbons are those who have ‘changed their lineage’ or we can say got ‘functionalized’ by groups of atoms containing nitrogen, oxygen, sulphur etc; at one spot in the chain or many; and thus generating the whole organic universe.
Understanding and solving hydrogen spectrum paved way to the birth of quantum physics and connected fundamental physics and chemistry.
Generating energy by capturing and storing hydrogen can pave way as an alternative to carbon based fossil fuels.