Natural gas (CH₄) and methanol (CH₃OH) provide much of the raw material for hydrogen today. Another source is water (H₂O). The hydrogen and oxygen in water can be dissociated by an electric current in a process called electrolysis.

Hydrogen may someday replace heavier compounds as a carrier of energy for transportation and many other applications. Low-cost technology that allows this odorless, colorless, diffuse gas to be collected and used may be decades away. But hydrogen's potential to provide clean energy has some people hopeful about a future “hydrogen economy” that would not rely on fossil fuels.

Figure 2 Rutherford model of a hydrogen atom