Comprehensive Atomic Theory and Experiments: Dalton, Thomson, Rutherford, Chadwick

What is incoreect about Daltons atomic theory

Atoms are NOT all identicle, because isotopeve diffrnet number if neutrons

Who was the first person to describe an atom

Democritus

Atoms

A fundamental unit of matter

What is matter made of

Small particles of atoms (Democritus said this)

Dalton

Studied ratios in which elements combine in chemical reactions.

John Joseph Thomson

Discovered negative particles using a cathode ray tube

Cathode Ray Tube

An experiment, in a tube with metal plates on both ends and an electric charge flowing through the gas inside.

What did the cathode ray tube determine and how

Determined electrons were all atoms, and were negative by showing they'd repel a negative plate (the metal plates)

Who made the plum pudding model

Jhon Joseph Thomson

What is the Plum Pudding Model

Positive charge spread over the entire spear, with electrons throughout

Crookes Tube

Put a spinning wheel in a cathode ray tube

What did the Crookes Tube determine.

Determined electrons have mass because they could push the pinwheel

Millikan

Did the oil drop experiment, and determine the value of the charge of the electron?

Millikan

Used Thomson's charge-to-mass ratio for electrons to calculate the mass of a single electron

The Oil Drop experiment

A tube with a metal plate, and an oil drop with electrons on it.

RUTHERFORD

Did the GOLD FOIL EXPERIMENT in order to support the Plum Pudding Model of the atom

Gold Foil Experiment

Gold Foil, tried to put alpha particles through the foil. Instead SOME of the particles bounced off

What did the Gold Foil Experiment determine

concluded that the nucleus must be very small compared to the entire atom

What is a alpha particle

positively charged particles made of 2 protons and 2 neutrons

CHADWICK

Compared the number of protons and mass of hydrogen and helium and realized there was potentially missing mass

Hydrogen Atom

1 proton, 1 electron, Mass: 1 amu

Helium atom

2 protons, 2 electrons, Mass 4 amu

What did Chadwick Devise

an experiment hitting lithium, beryllium, and boron with alpha particles to release a neutral subatomic particle, the neutron

What is the Mass of a proton approximately equal to

mass of a neutron (neutron slightly heavier)

How much heavier is a proton then electron

A proton is about 1840x heavier

What charge does a neutron have

no charge

The numerical charges of a proton and electron are perfectly opposite of each other

A=

mass number=number of protons + nuetrons

X=

Element Symbols

Z=

Atomic Number=Number of protons

Isotopes

Atoms of the same element with different numbers of neutrons

What does A-Z=

Neutrons

Average Isotopic Mass:

Atomic Mass x (Percent Abundance/100)

Average isotopic Mass, measure unit

g/mol

Rutherford's Model of the Atom

NUCLEUS IS EXTREMELY SMALL

Are atoms indestructible

They are NOT