Atomic History and Atomic Subparticles

Atom: the basic particle of the chemical elements.

Isotope: atoms with the same number of protons but different numbers of neutrons and thus different masses

Ion: an atom or molecule with a positive or negative electrical charge

Atomic number: the number of protons in the nucleus of an atom

Mass number: the total number of protons and neutrons in an atomic nucleus

Atomic mass unit (amu or μ): a unit for expressing masses of atoms, molecules, or subatomic particles

Average atomic mass: average mass of all natural isotopes

Symbol for proton: p⁺

Symbol for neutron: n⁰

Symbol for electron: e⁻

Proton mass in amu: 1

Neutron mass in amu: 1

Electron mass in amu: .000548

Protons and neutrons are located in the nucleus.

Electrons are located in the electron cloud.

The number of protons can be found by the atomic number

The number of neutrons can be found by subtracting the atomic number from atomic mass

The number of electrons can be found by the atomic number or number of protons

A = # of p⁺ + # of n⁰: Mass number

Z = # of p⁺: Atomic number

A is always above Z.

Democritus theorized the Atom Theory, where the world is a vertex where atoms link together

John Dalton proved atoms have fixed proportions and atoms of the same element are identical. He also created the Laws of conservation of mass, definite proportion, and multiple proportion

Dalton believed atoms were spheres

JJ Thompson discovered the electron and that all atoms contained negatively charged particles

The Cathode Ray Experiment was a cone where electricity on the narrow side passed through one (-) cathode to a (+) anode. It passes through a small hole on the (+) anode and went to a battery.

Ernest Rutherford discovered alpha and beta radiation through the Gold foil experiment.

In the Gold foil experiment, a radioactive source is shot to gold foil and it reflects, passes, or deflects to detectors.

Niels Bohr contributed to atomic structure and quantum theory. He made a basic model of the atom.

In Bohr’s model, electrons can only occupy certain spaces outside the nucleus and quantum leaps jump energy.

Average atomic mass is found by each mass of the isotope being multiplied by it’s corresponding abundance. These products are added together and divided by 100.

Electromagnetic Spectrum: RMIVUXG

R: Radio

M: Microwave

I: Infared

V: Visible

U: Ultraviolet

X: X-Ray

G: Gamma Ray

Frequency and wavelength are inversely related. Higher frequency means lower wavelength.

The higher the frequency, the higher the energy

The speed of light (C) = wavelength x frequency

Energy (E) = Planck’s constant (h) x frequency

Planck’s constant = 6.63 × 10^-34 J/sec

C = 3.0 × 10^8 m/s