Atoms, molecules, elements and compounds. Early Greek philosopher who coined the term atom

Atoms, molecules, elements and compounds

Democritus

Early Greek philosopher who coined the term atom.

John Dalton and atomic theory

It was in the early 1800s that John Dalton, an observer of weather and discoverer of color blindness among other things, came up with his atomic theory. Less than twenty years earlier, in the 1780's, Lavoisier ushered in a new chemical era by making careful quantitative measurements which allowed the compositions of compounds to be determined with accuracy. . .

Atoms are the smallest particle of matter that retains all the characteristics of the matter.

ElectronsElectrons are the negatively

charged particles of atom. Together, all of the electrons of an atom create a negative charge that balances the positive charge of the protons in the atomic nucleus. Electrons are extremely small compared to all of the other parts of the atom. The mass of an electron is almost 1,000 times smaller than the mass of a proton.

Protons

A proton is a subatomic particle found in the nucleus of all conventional atoms. The only place you can find matter without protons is in a neutron star or the core of powerful particle accelerators. The proton has a positive charge, which balances out the negative charge in atoms, electrons. If an atom has an imbalance of protons or neutrons, it is no longer neutral and becomes a charged particle, also known as an ion.

Neutrons

Subatomic particle that has no charge.

Molecules

A molecule is an electrically neutral group of two or more atoms held together by covalent chemical bonds. Molecules are distinguished from ions by their lack of electrical charge.

ELEMENTSElements are

substances made of only one type of atom.

Compounds

TWO OR MORE ELEMENTS CHEMICALLY COMBINED