Hydrocarbon, any of a class of organic chemical compounds composed only of the elements carbon (C) and hydrogen (H). The carbon atoms join together to form the framework of the compound; the hydrogen atoms attach to them in many different configurations. Hydrocarbons are the principal constituents of petroleum and natural gas.
Use slab in a sentence. 1  a piece that is flat, broad, and fairly thick: a slab of concrete, a slab of bread.  any of the rough, outer pieces cut from a log, as in sawing it into lumber.
In geologic terms, a plate is a large, rigid slab of solid rock. Putting these two words together, we get the term plate tectonics, which refers to how the Earth's surface is built of plates.