Notes on "Atom Notes"

* Supplemental notes

- The existence of atoms was first proposed by philosophers in
  ancient Greece (Leucippus, Democritus (c. 460 - c. 370 BC)) and India.

- The existence of atoms was proven by Einstein in 1905.

- The number of protons in an atom can change under the extreme
  conditions studied in nuclear physics, such as in an atomic bomb, a
  nuclear power plant, or the inside of a star.

* Quiz

- What is the atomic number of Helium? {2}

- What is the mass number of the Helium atom in the drawing? {4}

- * If the helium atom in the drawing loses an electron, what will
  happen to the atom's electric charge? {Will become +1 since there
  are two positively-charged protons but only one negative electron.}