History of Atomic Structure. Democritus Ancient Philosophy Who: Democritus When: 400 B.C. Where:...

History of Atomic Structure

Democritus

Ancient Philosophy• Who: Democritus

• When: 400 B.C.

• Where: Greece

• What: Democritus believed that matter was made of small, indivisible particles he named “atoms”.

• Why: Democritus used observation and inference to explain the existence of everything.

At this time in history, science was:

“What you see is what you get.”

John Dalton

Particle Theory• Who: John Dalton• When: 1803-1808• Where: England• What: Described atoms as tiny particles that

could not be divided (like billiard balls). Thought each atom of a given substance were identical.

• Why: Building on the ideas of Democritus in ancient Greece.

Solid Spheres

Dalton’s Atomic Theory1. All matter is composed of atoms

2. Atoms of same element are identical AND atoms of different elements are different

3. Atoms can’t be divided, created, or destroyed

4. Atoms of different elements combine to form compounds

5. In chemical reactions, atoms are combined, separated, or rearranged.

Does Dalton’s Atomic Theory Still Hold True Today???

• Dalton didn’t know about isotopes. All identical atoms are NOT identical because we have different forms of them.

• Dalton didn’t know about parts of an atom! They CAN be divided into parts! We now know about proton, neutron, electrons, nucleus etc.

J. J. Thompson

Discovery of Electrons• Who: J. J. Thompson

• When: 1904

• Where: England

• What: Thompson used Cathode Rays to discover that electrons were smaller particles of an atom and were negatively charged.

• Why: theorized that the neutral particles called atoms have no charge because it is actually made up of two types of charged parts, one positive and one negative so the charge cancels out.

J.J. Thompson’s Plum Pudding Model

NOTICE: NO nucleus!

Cathode Ray Tube

J.J. Thomson

Discovered mass/charge of e-

1906 Nobel Prize in Physics

Ernest Rutherford

Atomic Structure I• Who: Ernest Rutherford

• When: 1909

• Where: England

• What: Conducted a Gold Foil experiment to isolate the positive particles in an atom. Decided that the atoms were mostly empty space, but had a dense central core.

• Why: He knew that atoms had positive and negative particles, but could not decide how they were arranged.

• Rutherford’s Results:1.Most of the large positive particles went straight

through! (hit nothing)

2. Some were totally bounced back, hit something very hard and dense.

3. Some were deflected. In entirely different directions from each other!

Meant there were positive

AND negative particles/areas

inside!

The Nuclear Model: Extremely small, dense and positively charged nucleus surrounded by empty space sparsely occupied by electrons.

Niels Bohr

Atomic Structure II• Who: Niels Bohr

• When: 1913

• Where: England

• What: Proposed that electrons traveled in fixed paths around the nucleus. Scientists still use the Bohr model to show the number of electrons in each orbit around the nucleus.

• Why: Bohr was trying to show why the negative electrons were not sucked into the nucleus of the atom.

Planetary Model

• Electrons travel around the nucleus in orbits of that have a set energy level

• Scientists cannot predict where they will be at any given moment.

Planetary Model of Bohr’s atom

Bohr’s Atom

electrons in orbits

nucleus

• James Chadwick

• Who: James Chadwick

• When: 1932

• Where: England

• What: Identified third subatomic particle= the neutron

• Why: The earlier atomic models were missing mass

History of Atomic Structure. Democritus Ancient Philosophy Who: Democritus When: 400 B.C. Where:...

Documents

Timeline of Atomic Structure Marissa Kopelman. Democritus (460 B.C.-370 B.C.) Democritus, a Greek philosopher, believed that all matter was made up of

The Physics of Flight. Ancient Dreamers Legends of flight attempts date to 2000 B.C. Legends of flight attempts date to 2000 B.C. –Many believed flying

Models of the Atom a Historical Perspective Aristotle Early Greek Theories 400 B.C. - Democritus thought matter could not be divided indefinitely. 350

Atoms, Molecules, and Ions Defining the Atom The Greek philosopher Democritus (460 B.C. – 370 B.C.) was among the first to suggest the existence of atoms

Democritus Aristotle -400 B.C. - Coined the term “atom” -384-322 B.C. - Believed matter is continuous

Chapter 4 Atomic Structure. Democritus Greek Philosopher First to suggest the idea of atoms. Believed atoms were indivisible & indestructible

Chapter 4 “Atomic Structure”. Section 4.1 Defining the Atom Greek philosopher Democritus Greek philosopher Democritus (460 B.C. – 370 B.C.) suggested

FROM DEMOCRITUS ATOM TO QUARKS · 2018. 11. 12. · Democritus When Who Technology Theory 400 B.C. Democritus He took a seashell and broke it in half. He then took half of it and

The Atomic Model - d18n8r6t2iitwf.cloudfront.net · But First, Democritus! Democritus was a Greek philosopher (470-380 B.C.) who is the father of modern atomic thought. He proposed

Atoms and Their Structure History of the Atom n n Original idea (400 B.C.) came from Democritus, a Greek philosopher n n Democritus expressed the belief

“Atomic Structure -1” - Universitetet i oslofolk.uio.no/ravi/cutn/atomicphy/Atomic-Structure1.pdf · Defining the Atom The Greek philosopher Democritus (460 B.C. – 370 B.C.)

Atoms and their Structure History of the Atom n Original idea Ancient Greece (400 B.C..) n Democritus* and Leucippus: Greek philosophers

Atomic Theory - North Bergen School District · But before all these guys there was Democritus Democritus was a Greek philosopher (470-380 B.C.) who is the father of modern atomic

Chapter 4.1 Defining the Atom. Democritus (Greece 460 BCE) Believed that atoms were indivisible and indestructible. Believed that atoms were indivisible

Atoms and Their Structure Early Greek Theories 400 B.C. - Democritus crushed substances in400 B.C. - Democritus crushed substances in his mortar and

Atomic Theory. Defining the Atom The Greek philosopher Democritus (460 B.C. – 370 B.C.) was among the first to suggest the existence of atoms (from the

The Atomic Model - madeonamac.com · Dalton Thomson Rutherford Bohr Chadwick Modern. But First, Democritus! Democritus was a Greek philosopher (470-380 B.C.) who is the father of

Chapter Two The Atomic Theory of Matter Aristotle 400 B.C. - Democritus thought matter could not be divided indefinitely. 350 B.C - Aristotle modified

Development of Atomic Theory. Democritus GREECE around 400 b.c. Democritus said: –47 The material cause of all things that exist is the coming together

Development of Atomic Theory 400 B.C. -Democritus was first to use the word : atom atomos meaning “indivisible” Aristotle (famous philosopher) disputed