What is an atom, element, molecule, and compound? What is an example of each?

Question

What is an atom, element, molecule, and compound?   What is an example of each?

Olivia Anton · Accepted Answer

Atom is a particle of matter that characterizes a chemical element.

An atom is a particle of matter that characterizes a chemical element. It is the smallest part of ordinary matter. It is made from particles called protons, neutrons and electrons called the subatomic particles. An element is a substance that is made entirely of one type of atom. For example, the element sodium is made up of only sodium atoms. A molecule is a substance that contains two or more atoms chemically joined, such as #H_2, O_2# A compound is a substance that is made up of two or more different elements that are chemically joined, such as #H_2O, CO, NaCl#. Note: All compounds are molecules, but not all molecules are compounds.

Wyatt Atkins · Answer

undefined An atom is the smallest unit of matter that retains the properties of an element. Example: Hydrogen atom (H).

An element is a substance made up of only one type of atom. Example: Oxygen (O2).

A molecule is a group of atoms bonded together. Example: Water molecule (H2O).

A compound is a substance composed of two or more different elements chemically bonded together. Example: Sodium chloride (NaCl).