chemistry (elements)

Carbon dioxide is the compound of carbon, but NOT the gaseous form of carbon.

Carbon exists in different forms. For example, diamond is a form of carbon. The melting point (m.p.) and boiling point (b.p.) of diamond are 3527 degrees C and 4027 degrees C respectively.
This means: Between the m.p. and b.p. of diamond, carbon exists in liquid form. Above the b.p. of diamond, carbon exists as gaseous form.
Note that the heating process must be in the absence of oxygen. If not, carbon will reaction with oxygen in high temperatures to give the compound of carbon dioxide.

All common elements have liquid forms and gaseous forms. An element exists as its solid form below its m.p., as its liquid form between the m.p. and b.p., and as its gaseous form above its b.p. The m.p. and b.p. of carbon can be found in the reference webpage. The m.p. and b.p. of other elements can be found in the same website.