Question

Elements are pure substances made up of _____. atoms molecules compounds neutrons

Answer 1

Atoms

Step-by-step explanation:

Atoms are the smallest particle that can be identified from a chemical element and participate in chemical reactions.

All atoms are composed (at least) of a proton and an electron, and may also have neutrons (the hydrogen atom has no neutron).

Elements are substances composed of atoms of a certain type.

A molecule is formed when atoms of the same or different elements combine. A molecule is the smallest particle of a substance that can normally exist independently.

Example: A carbon atom combines with two oxygen atoms to form a carbon dioxide molecule [CO₂]

A compound is formed when atoms or molecules of different elements combine. In a compound, the elements are chemically combined in a fixed ratio.

Example: Hydrogen and oxygen are combined at a fixed ratio of 2: 1 to form the water compound [H₂O].

Answer 2

Answer: atoms

Step-by-step explanation:

An atom is smallest unit of a matter or substance.It consist of three subatomic particles : electrons, protons, neutrons. It may or may not have independent existence.

A molecule of element is formed by combination of atoms of similar elements.
`H_2`

A molecule of compound is formed by combination of atoms from different elements.Example:
`CuCO_3`

Element is a pure substance which is composed of atoms of similar elements. Example:
`Cu`

Compound is a pure substance which is made from atoms of different elements combined together in a fixed ratio by mass. Example:
`CuO`