History of Atomic Structure

Atoms: their parts & pieces

History of the atom

The atom starts not with the ________ of the atom, but the ______ of the atom.

More than ______ years ago, (around ____ BC) Greek philosophers ___________ and ____________ debated the nature of the universe.

historyidea

2000

Aristotle Democritus400

History of the Atom

Aristotle believed that all matter was made of ___ elements: ______, ____, ______ and _______.

4 EarthAir Fire Water

Democritus believed that matter was made of small particles called ______ that cannot be ___________.

atomssubdivided

Early Theories…

Who WON the Debate?Democritus based his theory on ____________, Aristotle based his on __________. Neither of them really did Neither of them really did _____________._____________.

observationphilosophy

__________ argued louder, so he won.Aristotle

Aristotle Democritus

experiments

Who Was Right?Aristotle’s ideas carried through until the Aristotle’s ideas carried through until the _____________._____________.

A branch of ‘science’ called _________ A branch of ‘science’ called _________ was introduced in Europe the was introduced in Europe the 1200’s1200’s AD AD

Alchemists tried to change ______ to Alchemists tried to change ______ to ______.______.

Middle Ages

alchemy

leadgold

____________was actually RIGHT!!Democritus

Alchemy

In 1661, a chemist named ________ In 1661, a chemist named ________ _______ believed that all matter was _______ believed that all matter was made of simple substances called made of simple substances called _________ that could not be _________ that could not be ____________ or _____________.____________ or _____________.

RobertBoyle

elementsdecomposed broken down

Boyle’s theory was not _________ for Boyle’s theory was not _________ for more than ____ years, since he had no more than ____ years, since he had no way to ______ his theory.way to ______ his theory.

accepted100

prove

Father of Atomic TheoryModern atomic theory was developed in Modern atomic theory was developed in 1809 by an English scientist named _____ 1809 by an English scientist named _____ ________.________.

His theories were based on His theories were based on ___________ and ___________ and ____________.____________.

John Dalton

observations experiments

Dalton’s Atomic Theory1. _______ is made of small particles or 1. _______ is made of small particles or ______.______.

Matter atoms

2. Atoms cannot be ________ or 2. Atoms cannot be ________ or _________._________.

createddestroyed3. All atoms of an element are ________ 3. All atoms of an element are ________ and have the same _____.and have the same _____.

identicalmass

4. Atoms of different elements have 4. Atoms of different elements have different _______. different _______. masses5. ___________ are formed by combining 5. ___________ are formed by combining different elements. different elements.

Compounds

Dalton’s Atomic Theory

In _____, an English physicist named In _____, an English physicist named ______________ did experiments to ______________ did experiments to determine the parts that make up the determine the parts that make up the atom.atom.

1897J.J. Thomson

He created a ________ ray tube: a He created a ________ ray tube: a _______ tube where all the ____ has _______ tube where all the ____ has been pumped out and a limited amount of been pumped out and a limited amount of other ______ is pumped in.other ______ is pumped in.

cathode vacuum air

gases

Who’s Next?

Thomson’s Experiment

Voltage source

+-

Metal Disks

Passing an electric ________ makes a Passing an electric ________ makes a beam appear to move from the beam appear to move from the ________ to the ________ end________ to the ________ end

Thomson’s ExperimentThomson’s Experiment

Voltage source

+-

current

negative positive

Voltage source

Thomson’s ExperimentThomson’s Experiment

By adding an electric field to the By adding an electric field to the _______ of the tube, he discovered that _______ of the tube, he discovered that the moving pieces were _________.the moving pieces were _________.

+

-

outsidenegative

Thomson’s Model

The negatively charged particles were _________electrons

plum pudding

positive

removed

Said the atom was like Said the atom was like ________________________

A bunch of ________ A bunch of ________ stuff, with the stuff, with the electrons able to be electrons able to be ________.________.

Rutherford’s ExperimentIn _____, an English physicist named In _____, an English physicist named _________________ continued _________________ continued Thomson’s work.Thomson’s work.

1910Ernest Rutherford

He believed the plum pudding model was He believed the plum pudding model was correct, and he wanted to discover the correct, and he wanted to discover the _____ of atoms._____ of atoms.size

Rutherford used thin __________ sheets Rutherford used thin __________ sheets and ___________ material.and ___________ material.

gold foilradioactive

Rutherford’s experiment

The radioactive material released ______ The radioactive material released ______ particles, which connected with a fluorescent particles, which connected with a fluorescent screen and caused it to _____.screen and caused it to _____.

alpha

glow

This is what it looked like:This is what it looked like:

Lead block

Uranium

Gold Foil

Fluorescent Screen

He Expected:

The alpha particles to pass through without ________ _________ very much.changing direction

positiveevenly

Because…Because…

The ________ charges were spread out The ________ charges were spread out _______, and were not enough to stop the _______, and were not enough to stop the positively-charged alpha particles.positively-charged alpha particles.

What he expected

Because

Rutherford thought the mass was evenly distributed in the atom

Rutherford thought the mass was evenly distributed in the atom

What he got

How he explained it:

+

Atoms are mostly Atoms are mostly ______ ______.______ ______.empty space

There is a ______, There is a ______, _______, ________ _______, ________ piece at the center of piece at the center of the atom – called the the atom – called the ________.________.

smalldense positive

nucleus

Positive alpha particles are _________ by Positive alpha particles are _________ by the nucleus if they get close enough…the nucleus if they get close enough…

deflected

Nucleus

+

The Bohr ModelOur modern model of the atom comes from Our modern model of the atom comes from a Danish chemist named _____ _____, a Danish chemist named _____ _____, who developed it in _____.who developed it in _____.

Niels Bohr

_________ and _________ and _________ are _________ are located in the nucleus.located in the nucleus.

Protonsneutrons

_________ are _________ are located in orbit around located in orbit around the nucleus.the nucleus.

Electrons

1913

Modern View of the AtomThere are _____ different types of particles There are _____ different types of particles that make up the atom.that make up the atom.

three

Make a TIMELINE!

• Using your notes, make a timeline of Atomic Events in History!

• Use the paper provided and the colored pencils!

• Make it creative, but ACCURATE!

• Include pictures, too!