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

The 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

Where protons and neutrons located

Nucleus

Where electrons are located

Electron cloud

Number of neutrons can be found by

Subtracting atomic number from atomic mass

A = # of p+ + # of n0

Mass number

Z = # of p+

Atomic number

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

Dalton believed

atoms were spheres.

JJ Thompson

discovered the electron and that all atoms contained negatively charged particles.

The Cathode Ray Experiment

a cone where electricity on the narrow side passed through one (-) cathode to a (+) anode

Ernest Rutherford

discovered alpha and beta radiation through the Gold foil experiment.

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

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 its corresponding abundance, added together, and divided by 100

Electromagnetic Spectrum

RMIVUXG

R

Radio

M

Microwave

I

Infrared

V

Visible

U

Ultraviolet

X

X-Ray

G

Gamma Ray

Frequency and wavelength are

inversely related

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 value

3.0 × 10^8 m/s.

Atomic Emission Spectrum

the pattern of lines formed when light passes through a prism to separate it into the different frequencies of light it contains