ATOMS

1. Atomic Structure

1.1. Atomic Mass

1.2. Atomic Number

1.3. Inside The Nucleus

1.3.1. Protons

1.3.1.1. Neutrons

1.4. Outside the Nucleus

1.4.1. Electrons

1.5. Isotopes

2. What is Atom?

2.1. An atom is the basic unit of an element. An atom is a form of matter which may not be further broken down using any chemical means. A typical atom consists of protons, neutrons, and electrons.

3. What is Element?

3.1. In chemistry, an element is a pure substance consisting only of atoms that all have the same numbers of protons in their atomic nuclei

3.1.1. Metals

3.1.1.1. Alkali metals

3.1.1.1.1. Alkine Earth metals

3.1.2. Metalloids

3.1.3. Non-Metals

3.1.3.1. Noble gases

3.1.3.1.1. Halogens

4. Electronegativity

4.1. Electronegativity, symbol x measures the tendency of an atom to attract a shared pair of electrons (or electron density).

5. In 1932, Chadwick found out that the mass of the atoms is concentrated with the nucleus of the atom.

6. Democritus

6.1. Democritus stated that all matter is made of tiny indestructible units call atoms.

7. Aristotle and Plato

7.1. Until Aristotle and Plato completely disagreed with Democritus' statement. They say that all matter is made of Earth, Fire, Water and Air.

8. John Dalton

8.1. Early 1800, Dalton considered Democritus' idea of atoms. He invented his own atom ball model.

9. J.J. Thomson

9.1. In 1897, J.J. Thomson discovered the Electron. He used cathode ray tube to deduce the presence of a negative charged particle.

10. Ernest Rutherford

10.1. Years after, Rutherford reasoned that all of an atom's positively charged particles were contained of nucleus. He also invented his own Nuclear Atom

11. Niels Bohr

11.1. 2 years after, Niels Bohr proposed an improvement in his model which he placed each electron in a specific energy level called shells or orbit.

12. James Chadwick