Atomic TheoryHistory of the Discoveries Related to the Atom

Mrs. Paul

Main Contributors To Atomic Theory 450 BC 1800 1897 1901 1910 1911 1913

Democritus: Matter made of tiny things

called ATOMS

Dalton: Wrote an Atomic

Theory with 4 main ideas

Thompsonnegative charge in the atom

Planck: Quanta,

predictable packets of

energy

Millikan: Charge on

the electron of -1

Rutherford: atoms have a nucleus

Bohr: Proposed a model of an

atom

1924 1926 1926 1932 1962

Debroglie: Matter has a

wave-like nature

Schrödinger: E- travel in

waves

Heisenberg: E- are waves and particles

Chadwick: neutrons

Gell-Mann: Quarks

Timeline of Atomic Theory 450 BC 1800’s

_________________________________________________________

Democritus:

matter was made of “atoms”

Dalton:

proposed 4 components to an

Atomic Theory.

Dalton’s Theory: Foundation of Future Investigations

• All matter consists of tiny particles. • Atoms are indestructible and

unchangeable (Has been modified with recent discoveries in nuclear chemistry)

• Elements are characterized by the mass of their atoms.

• When elements react, their atoms combine in simple, whole-number ratios. Their atoms sometimes combine in more than one simple, whole-number ratio.

Click the picture to explore more about experiments

related to Dalton’s theory.

Atomic Theory 1897-1962Sub-Atomic Particles

___1897________ 1910________ 1911_________1913________1932________1962___

Thomson Cathode Ray Experiment

Negative charge in the atom

RutherfordGold Foil Experiment

Alpha Particles and Nucleus Animation

Nucleus

Bohr Bohr Model

Bohr’s Discovery

Quantum Model

Millikan Oil Drop Experiment

Charge on e- is 1-

ChadwickHistory of Chadwick

Neutron

Gell-MannWhat are p+ and n0?

Quarks

3 Basic Parts of the Atom. Click on this link and participate in the interactive questions

Types of Quarks Determine Charge http://nobelprize.org/educational_games/physics/matter/1.html

Quarks = up (+2/3) and down (-1/3) p+ = 2ups and 1 down n0 = 2 down and 1 up

+2 +2 -1 = +1 -1 -1 +2 = 0

3 3 3 3 3 3

Gluon forces between quarks

Energy Nature of Matter 1900-1926

____________1905______1924_____1926______1926__

De Broglie Wave

nature of matter

Heisenberg

Uncertainty

e- acts as a wave and a

particle

Schrodinger

e- orbits as a wave

1900

Planck

Quantum Hypothesis

Atoms Absorb and Emit Light

Photo Electric Animation

Quanta

EinsteinMatter and Energy different forms of the same thing

E=mc2 Explained

E=mc2

Electrons……..

Are they a particle or a wave?

Electrons travel in wavesClick this link for explanation

Electrons as Waves Electrons travel in discreet packets called photons which

travel in waves. • To describe these unique packets or quantities of

energy the term “quanta” is used. • Every element on the periodic table is made up of atoms

with a unique signature of spectral lines. Click the picture below

Electron behavior as it moves to other energy levels.

• This emitted energy is equal to the difference between the high and low energy levels, and may be seen as light.

Click the picture for animation

Electrons as a Particle having position in an Atom

• Electrons are particles with a charge of 1- , it has mass, and its position can be predicted with reliability.

Bohr proposed 4 characteristics to predict the position of an electron.

l = the distance from the nucleus

m = the shape of the orbital in which the e- occupies. (s,p,d,f)

n = axis the orbital occupies. (x, y, z)

s =spin of the e- (+1/2 , -1/2)

1. Distance from the nucleus

• Levels 1-7: When looking at the periodic table, can be determined by the period number. Elementary Connections

12

34

56

7

2. Shape of the Orbital

3. On the x,y,z Axis

The # of electrons in a particular region determines the shape. s shape 2e- p shape 6 e- d shape 10 e-

f shape 14 e-

Atom with overlapping orbitals

4. Spin of the Electron

Electrons exhibit particle and wave like behavior called “Duality”

Click here for animation

Einstein vs BohrEinstein: causality Bohr: Predictability

If you know all the initial conditions of

your system and you know the laws of

physics, you can figure out exactly what’s going to happen

If you know the initial

conditions and you know the

laws of physics, you

can figure out the probability

of various outcomes

happening, but you can never know which

one will definitely occur until after it’s

over.

Particles of the Atom to date:• Nucleus

– Protons = p+ = 3 quarks

– Neutrons= n0 = 3 quarks

• Electron Cloud

– Electrons =e- (particle/wave)• http://www.youtube.com/watch?v=ol_FrffMoQ8• http://www.youtube.com/watch?v=45KGS1Ro-sc• http://www.youtube.com/watch?v=fm7oGOdsaQk• http://www.teachersdomain.org/asset/lsps07_vid_stability/

 

Held together by a force called :

Gluon