Answer:
-Why is Democritus important with regard to atomic theory? Democritus developed his atomic philosophy as a middle ground between two opposing Greek theories about reality and the illusion of change. He argued that matter was subdivided into indivisible and immutable particles that created the appearance of change when they joined and separated from others.
-Dalton's atomic theory was the first complete attempt to describe all matter in terms of atoms and their properties.
-What subatomic particle did JJ Thomson discover? He discovered the electron in 1897.
-In 1913, Neils Bohr proposed a new atomic model known as the Bohr's model, which is patterned after the solar system.
- List the principles of Bohr's model:
a. An electron moves around the nucleus in a circular orbit.
b. An electron's angular momentum in the orbit is quantisized.
c. The change in an electron's energy as it makes a quantum jump from one orbit to another is always accompanied by the emission or absorption of a photon.
- In 1926, Erwin Schrödinger used mathematical equations to describe the likelihood of finding an electron in a certain position. This model is known as the Rutherford Model of an atom.
-In 1932, James Chadwick discovered the neutron.
-Since 1932, the atomic theory has been further enhanced by the concepts that protons and neutrons are made of even smaller units called quarks. The quarks themselves are in turn made of vibrating strings of energy.
-Everything in the universe (except energy) is made up of matter.
-Therefore everything in the universe is made up of atoms.
-An atom itself is made up of three tiny kinds of particles called subatomic particles: protons, neutrons and electrons.
The protons and the neutrons make up the centre called the nucleus.
The electrons fly around above the nucleus in a small cloud.
The electrons carry a negative charge and the protons carry a positive charge.
In a normal (neutral) atom the number of protons is the same number of electrons.
