a chemical change
As a compound
An element occur in nature as a pure element or as a compound.
Element
That's because of the way "compound" is defined. If atoms of an element combine with other atoms of the SAME element, then it's not called a "compound".
Cobalt, the transition metal, is an element. It's element number 27, and it does not occur naturally as an element or as a mixture, but rather as a compound. Links are provided.
Rearranged
When one element replaces another element in a compound during a chemical reaction
Physical Change
the answer is that it occurs as a compound, not an element
When a compound is mixed with an element. KCl is more than one element put together, thus it is a compound. Sodium (Na) is an element, so if you combine the two, it is a single replacement reaction.
When energy is removed from a gas, condensation occurs. When energy is removed from a liquid, freezing occurs.
A new compound must be obtained.