The Chemistry of the Atomic Bomb (Level 4)

Level 4: Comparison between Atomic and Hydrogen Bombs

For atoms lighter than Nickel-62, the stability of the nucleus increases as atomic mass (nucleon number) increases. Hydrogen bombs derive their energy from nuclear fusion when two light atomic nuclei fuse to form a heavier, more stable nucleus. (Refer to Level 4 of Physics for more information on nuclear fusion) 

As you have learnt in level of chemistry, the nucleus of an atom contains the positively charged protons and electrically neutral neutrons. This thus makes nuclei positively charged. Extremely high temperatures are required for the positively charged nuclei to overcome their mutual repulsion and gain enough kinetic energy to fuse. Deuterium (hydrogen-2) and tritium (hydrogen-3) are isotopes of hydrogen, and carry weak positive charges due to them only having 1 positively charged proton, making it easier to overcome their mutual repulsion and fuse into helium. 

As seen from the diagram above, hydrogen bombs rely on a fission reaction to compress the fusion fuel lithium-6 deuteride of chemical formula ⁶Li²H. Neutrons produced in the fission reaction bombard lithium-6 deuteride to produce tritium. The deuterium and tritium then fuse to produce helium-4 which has a more stable nucleus.

	Atomic Bombs	Hydrogen Bombs
Mechanism	Nuclear Fission: splitting of heavy isotopes into smaller atoms	Nuclear fusion (fusion of nuclei of lighter atoms into larger, more stable ones) caused by fission
Cost	Expensive: rare isotopes used require enrichment to obtain a supercritical mass.	Expensive: needs both fission and fusion components.
Energy needed	Less	More as a high density & high temperature environment is required for nuclear fusion
Energy produced	Less: about 20 kilotons of TNT	More: about 10 megatons of TNT