hydrogen     Key Data

 (Image: www.webelements.com)

Element Name

Hydrogen

Element Symbol

H

Atomic Mass

1.00794 amu

Atomic Number

1

Melting Point

-259.2 degrees °C

Boiling Point

-252.8 degrees °C

Natural State

Gas

Density in Natural State

Density as Solid

.08 g/ml  

Natural Abundance

Hydrogen ranks ninth of all the elements abundant on Earth and make up about ,76% of the weight of the Earth's crust. According to the latest estimate, Hydrogen makes up more than 90% of all the atoms or three-quarters of the mass of the universe.

Number of Isotopes

3
Name of Isotope Mass of Isotope (amu) Natural Abundance (%) Notes
Protium 1.000794 99.985 (70) STABLE Occurs in nature; proportions roughly 6,000:1
Deuterium 2.0140 0.0115 (70) STABLE Occurs in nature; proportions roughly 6,000:1. This isotope of hydrogen when combined with oxygen forms D2O, what is familiarly known as heavy water. 
Tritium 3.01605 Doesn't occur in natural H2 in detectable amounts, but can be made by atomic bombardments (of deuterium by deuterons). This heaviest isotope of Hydrogen is a radioactive gas with a half life of about 12 1/4 years. It is used in luminous paints, in the hydrogen bomb and as a tracer.

Chemical Properties/Reaction Tendencies:

  At room temperature, Hydrogen is a colorless, odorless, tasteless gas. Hydrogen is inactive at room temperature, only able to react with the halogen Fluorine in the dark at room temperature forming hydrogen (1) flouride.

H2(g) + F2(g) --> 2HF(g)

 Hydrogen is non toxic and non corrosive. An exposure to ultraviolet light will allow a reaction between Hydrogen and Chlorine to occur. Hydrogen reacts with many elements upon heating. When ignited it burns with air combining with Oxygen to form water. It produces a very pale blue and very hot flame. The mixture with Oxygen in the mole ratio 1:2, O2:H2 reaction upon ignition is violently explosive. A reaction between Hydrogen and air (oxygen in the air) will take place with prior ignition by a flame or spark leading to a resulting fire or explosion with a characteristic blue flame. While Hydrogen's flame is very hot, it's flame burns out quickly and there is little heat radiation. You would have to stand directly in the fire to get burned. The flame dissipates so quickly compared to natural gas. In a vehicle fire, hydrogen would stop burning after about two minutes, while natural gas would continue burning to about twenty or thirty minutes (IEA). The only product of the dangerous reaction is water. This reaction would be similar to what you get in the lab mixing O2:H2 together because both are violent. 

Click here to see the reaction of Hydrogen with Oxygen 

 The explosion of the Hindenberg balloon was an event in history that experienced this type of reaction. Check out the history page to see a ray tracing image of the Hindenberg balloon..

2H2(g) + O2(g) --> 2H2O(l)

While Hydrogen combined with Oxygen forms water, Hydrogen does not react with water. Hydrogen also doesn't react with dilute acids or dilute bases.

Natural Abundance of Hydrogen:
Abundance parts per billion (109) by weight parts per billion (109) by atoms
Universe 750,000,000 930,000,000
Sun 750,000,000 930,000,000
Meteorite (carbonaceous) 24,000,000 170,000,000
Crustal rocks 1,500,000 31,000,000
Sea Water 107,800,000 662,000,000
Stream 115,000,000 110,000,000
Human 100,000,000 620,000,000