History of the Atom

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Significance of Aristotle and problem

States matter is continuous and not made of smaller particles

Didn't have evidence

Significance of Democritius and problem

Says the world is made of two things: empty space and tiny particles called atoms (atomus → invisible)

Didn't have evidence

Law of Conservation of Matter

Matter is not created nor destroyed. It's only rearranged

Mass of reactants= Mass of products

Law of Electrical Charges

Opposite charges attract and like charges repel.

Law of Definite Proportions

Atoms must combine in whole number ratios

Father of Modern Atomic Theory

John Dalton

(Dalton’s Atomic Theory) TRUE OR FALSE:

All matter is made up of atoms. Atoms are the smallest fundamental units of matter.

True

(Dalton’s Atomic Theory) TRUE OR FALSE:

All elements consist of atoms which are indivisible and indestructible. 

False. Evidence: Nuclear Reactions

(Dalton’s Atomic Theory) TRUE OR FALSE:

All atoms of the same element are identical in size, shape, and mass

False. Evidence: Isotopes

(Dalton’s Atomic Theory) TRUE OR FALSE:

Atoms of different elements are different in size, shape, and mass. 

True. 

(Dalton’s Atomic Theory) TRUE OR FALSE:

In a chemical reaction, atoms are rearranged, never created nor destroyed and they combine in whole number ratios. 

True

A solid sphere, everything else is empty space. Who’s atomic model fits this description?

John Dalton

Who theorized the atom structure MIGHT be related to electricity… it might have a charge,

Michael Faraday

Who discovered there are positive charges and negative charges

Benjamin Franklin

Who’s responsible for the plum pudding model

JJ Thomson 

All atoms contain electrons. Since all atoms were neutral, there must be some positive charge spread throughout the atom to balance the negative and keep the atom neutral. 

This conclusion was drawn from the ______ experiment

Cathode Ray Tube

Who’s atomic model?

Ernest Rutherford

The ______ experiment proved all protons aren’t spread throughout the atom, they’re clumped together in the middle (nucleus).

Gold Foil

Provide the explanation for the following observation from the Gold Foil Experiment:

Most positive charges passed through because…

the atom is mostly empty space

Provide the explanation for the following observation from the Gold Foil Experiment:

Some of the positive charges deflected because…

the atom contains some positive charge

Provide the explanation for the following observation from the Gold Foil Experiment:

Some of the positive charges deflected straight back because…

there is a concentrated area of positive charge

Who is responsible for the Solar System Model

Niels Bohr

Problem with the Solar System Model

It only worked for hydrogen, all other elements failed

the more precisely the location of an electron is determined the less precisely speed is known

Heisenberg’s Uncertainty Principle

Found that electrons sometimes act like waves or particles. aka ______

Lous de Brogile, wave particle duality

lamda (𝜆), distance from crest to crest or trough to trough (meters or nanometers)

Wavelength

nu, the # of wave cycles that pass a given point (hertz or 1/s or s^-1)

Frequency

The _______ spectrum

electromagnetic

Shorter wavelength = _____ frequency, _____ energy

higher frequency, higher energy

Longer wavelength = _____ frequency, ______ energy

lower frequency, lower energy

λ x 𝜈 = c

(lambda x nu = speed of wave)

what does c =

c= speed of light = 2.99 × 10⁸m/s

Outermost electrons in an atom

Valence electrons

• Any amount of E(energy) could be gained or lost by any object

• This would result in a continuous line spectrum

What is this theory called?

Classical Theory Physic

• Any amount of E(energy) could be gained or lost by any object

• This would result in a continuous line spectrum

True or false, If false what theory disproves

False, Quantum Theory

_______ Theory

When atoms or molecules absorbs or emits energy, it must be a specific amount called a quanta

Quantum