Final answer:
Allotropes are the different types of carbon atoms, such as diamond, graphite, and fullerenes, that have different properties but still form four bonds.
Step-by-step explanation:
The term for the different types of carbon atoms is allotropes. Allotropes are different structural modifications of an element. Carbon, for example, exists in several allotropic forms like diamond, graphite, and fullerenes.
These allotropes have different physical and chemical properties, but the carbon atoms in all three forms still form four bonds.