Helium and nickel are examples of . These
are pure substances that can not be broken
down into simpler materials.

Elements, in turn, are pure substances—such as nickel, hydrogen, and helium—that make up all kinds of matter.

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conduction is the transfer of thermal energy (heat in transfer) due to collisions between the molecules in the object. collisions between adjacent atoms and molecules transfer kinetic energy from the warmer to the cooler object. the objects must be in physical contact.