Question

A molecule is two or more atoms that are bonded together. For instance, oxygen is rarely found as just an O atom, but instead is found as two atoms bonded together in one molecule, O₂. Both O and O₂ are elements because they are composed of only one type of element. A compound is composed of two different types of elements. Can you have an atom of a compound like you can an element, or can you only have a molecule of a compound?

Answer 1

oxygen can exists as O and O₂ in that case O is known as element

and O₂ is known as Molecule of Element

Molecules are two types 1) = Molecule of Element

                                           2) = Molecule of Compound

1) => Molecule of Element = composed of same element

examples are H₂ (from hydrogen)

                       X₂ (from halogen) like F₂ ,Cl₂ ,Br₂ , I₂

                      N₂ (from nitrogen)

2) => Molecule of Compound = two or more different elements forms

   example = H₂O (from one oxygen and 2 hydrogens)

                   = CO₂ (from one carbon and 2 oxygens)