​What are Atoms

​The atom is considered the basic building block of matter. Anything that has a mass—in other words, anything that occupies space—is composed of atoms. While its name originally referred to a particle that couldn't be divided any more—the smallest thing possible—we now know that each atom is generally made up of smaller particles. Given that these particles make up atoms, they are often referred to as subatomic particles. There are three subatomic particles: protons, neutrons and electrons

​Examples of Atoms

​ Neon (Ne)

• Hydrogen (H)Argon (Ar)

• Iron (Fe)

• Calcium (Ca)

• Deuterium, an isotope of hydrogen that has one proton and one neutron

• Plutonium (Pu)

• F^-, a fluorine anion

• Protium, an isotope of hydrogen

​Molecules

​A molecule is an electrically neutral group of two or more atoms held together by chemical bonds. Molecules are distinguished from ions by their lack of electrical charge . In quantum physics, organic chemistry, and biochemistry, the distinction from ions is dropped and molecule is often used when referring to polyatomic ions .

​Examples of Molecules

​Water - H₂O

• Ammonia - NH₃

• Sulfur dioxide - SO₂

• Hydrogen sulfide - H₂S

• Ethanol - C₂H₆O