Atomic Theory Past and Present. A. Democritus (400 BCE) Matter is made up of particles called...

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Atomic Theory Past and Present

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Transcript of Atomic Theory Past and Present. A. Democritus (400 BCE) Matter is made up of particles called...

Page 1: Atomic Theory Past and Present. A. Democritus (400 BCE) Matter is made up of particles called “atomos” or atoms .

Atomic Theory

Past and Present

Page 2: Atomic Theory Past and Present. A. Democritus (400 BCE) Matter is made up of particles called “atomos” or atoms .

A. Democritus (400 BCE)

Matter is made up of particles called “atomos” or atoms

http://www.timelineindex.com/content/view/1228

I. Early Atomic Theory

Page 3: Atomic Theory Past and Present. A. Democritus (400 BCE) Matter is made up of particles called “atomos” or atoms .

B. John Dalton’s Atomic Model (1808)

•1) Atoms are hard spheres which cannot be further broken down.

•2) Atoms of one element are exactly alike, but different from atoms of another element.

Oxygen Hydrogen

Page 4: Atomic Theory Past and Present. A. Democritus (400 BCE) Matter is made up of particles called “atomos” or atoms .

•3)Law of Multiple Proportions

H2O

WaterH2O2

Hydrogen Peroxide2 grams H + 16 grams O2 grams H + 32 grams O

•Compounds always break down into simple ratios of elements by mass.

Page 5: Atomic Theory Past and Present. A. Democritus (400 BCE) Matter is made up of particles called “atomos” or atoms .

C. Thomson’s Atomic Model“Plum Pudding” (1897)

•JJ Thomson discovered all elements contain ELECTRONS by using the cathode ray tube; Electrons are small, negatively charged particles.

http://www.aip.org/history/electron/jjcrooke.htm

Page 6: Atomic Theory Past and Present. A. Democritus (400 BCE) Matter is made up of particles called “atomos” or atoms .

D. Eugene Goldstein (1900)

• Discovered the proton using the cathode ray tube. The “canal rays” traveled in the opposite direction of the electron beam.

• Protons are positively charged as compared to electrons but protons are much more massive.

Page 7: Atomic Theory Past and Present. A. Democritus (400 BCE) Matter is made up of particles called “atomos” or atoms .

E. Rutherford’s Atomic Model“Planetary” (1911)

•Rutherford discovered that all atoms contain a dense, positively-charged nucleus.

•Most of the atom is empty space.

Page 8: Atomic Theory Past and Present. A. Democritus (400 BCE) Matter is made up of particles called “atomos” or atoms .

Gold Foil Experiment

http://www.regentsprep.org/Regents/physics/phys05/catomodel/ruther.htm

Page 9: Atomic Theory Past and Present. A. Democritus (400 BCE) Matter is made up of particles called “atomos” or atoms .

F. Bohr’s Atomic Model“Quantized Electrons” (1913)

•Electrons are only allowed certain, specific energies.

•Electrons can be on the rings but not in-between.

For now, the electron pattern is

2: 8: 8: 2

Page 10: Atomic Theory Past and Present. A. Democritus (400 BCE) Matter is made up of particles called “atomos” or atoms .

Emission and Absorption Spectra

http://www.cbu.edu/~jvarrian/252/emspex.jpg

H

Hg

Ne

H

Page 11: Atomic Theory Past and Present. A. Democritus (400 BCE) Matter is made up of particles called “atomos” or atoms .

G. Sir James Chadwick (1932) Discovered the neutron

• Chadwick found that the particles given off by polonium increased the mass of the atoms but not their charge—evidence of the neutron (same mass as a proton but neutral)

Page 12: Atomic Theory Past and Present. A. Democritus (400 BCE) Matter is made up of particles called “atomos” or atoms .

IN SUMMARY• Atoms contain a dense nucleus with

protons and neutrons.• Atoms are mostly empty space.• The nucleus has electrons orbiting

around the nucleus in discrete energy levels.

• Electron-small mass, negative• Proton-much larger mass, positive• Neutron-about same mass as proton,

no charge

If this is your vision of an atom, you are back in the 1920’s!!

Page 13: Atomic Theory Past and Present. A. Democritus (400 BCE) Matter is made up of particles called “atomos” or atoms .

II. Atomic Model moves from the planetary view into

Quantum Theory (1920’s)

• Quantum Theory is based on waves (electrons behave like both particles and waves) and probabilities

Page 14: Atomic Theory Past and Present. A. Democritus (400 BCE) Matter is made up of particles called “atomos” or atoms .

Light as Waves

http://ircamera.as.arizona.edu/NatSci102/lectures/light.htm

Page 15: Atomic Theory Past and Present. A. Democritus (400 BCE) Matter is made up of particles called “atomos” or atoms .

Several scientists have contributed to Quantum

Theory

Page 16: Atomic Theory Past and Present. A. Democritus (400 BCE) Matter is made up of particles called “atomos” or atoms .

A. Max Planck (1900)• Light had been thought of as WAVES.

• Higher energy means higher frequency.• Light is composed of tiny packets (photons) of quantized energy.• Light can also act like particles!

Page 17: Atomic Theory Past and Present. A. Democritus (400 BCE) Matter is made up of particles called “atomos” or atoms .

B. Louis de Broglie (1923)

• Quantum numbers could describe BOTH the orbits of electrons and the spectral lines produced.

• Particles can act like waves

Page 18: Atomic Theory Past and Present. A. Democritus (400 BCE) Matter is made up of particles called “atomos” or atoms .

C. Werner Heisenberg (1925)

• Discovered that we can’t know exactly both speed and position of electrons—the “Uncertainty Principle”—because our methods of measuring atoms disturbs them.

Page 19: Atomic Theory Past and Present. A. Democritus (400 BCE) Matter is made up of particles called “atomos” or atoms .

D. Erwin Schrödinger (1926)

• Did “The Math” and put it all together• He treated electrons mathematically as waves

• We can’t know exactly where an electron is, but we can give a location of high probability

Page 20: Atomic Theory Past and Present. A. Democritus (400 BCE) Matter is made up of particles called “atomos” or atoms .

E. Max Born (1926)Electron Probability

http://www.regentsprep.org/Regents/physics/phys05/catomodel/ruther.htm

Born introduced the idea of probability in describing the atomic world—we don’t know exactly where the electron is but we have a pretty good idea where it probably is.

Page 21: Atomic Theory Past and Present. A. Democritus (400 BCE) Matter is made up of particles called “atomos” or atoms .

Modern Atomic ModelSummary—“Quantum Mechanics”

•Electrons are like waves.

•We can’t know exactly where electrons are, only where they are most likely.

Page 22: Atomic Theory Past and Present. A. Democritus (400 BCE) Matter is made up of particles called “atomos” or atoms .

Orbital Quantum Number

•Gives the shape of the orbital cloud (within 90% probability)

s orbital—

spherical

Page 23: Atomic Theory Past and Present. A. Democritus (400 BCE) Matter is made up of particles called “atomos” or atoms .

Orbital Quantum Numberp orbitals—”dumbbell” shaped or similar to a “figure 8”

Page 24: Atomic Theory Past and Present. A. Democritus (400 BCE) Matter is made up of particles called “atomos” or atoms .

Orbital Quantum Numberd orbitals—shape has 4 “lobes”

Page 25: Atomic Theory Past and Present. A. Democritus (400 BCE) Matter is made up of particles called “atomos” or atoms .

Orbital Quantum Numberf orbitals—some people describe a

“daisy-like”

http://www.d.umn.edu/~pkiprof/ChemWebV2/AOs/index.html www.chem.ous.ac.jp

Page 26: Atomic Theory Past and Present. A. Democritus (400 BCE) Matter is made up of particles called “atomos” or atoms .

III. What makes up protons and neutrons? Quarks!

• During the 1960’s various physicists discovered fundamental particles, known as quarks

• Protons and neutrons are made up of quarks

• Electrons are also fundamental particles

Page 27: Atomic Theory Past and Present. A. Democritus (400 BCE) Matter is made up of particles called “atomos” or atoms .

IV. What is the most recent theory? String Theory (late

20th Century to present)• All fundamental particles are made

of vibrating strings/strands of energy http://www.columbia.edu/cu/record/23/18/14.html


Physical Science CHEMICAL BONDS. Atomic Models in History Democritus, Greek philosopher, around 400 BC used the term “atomos” which means “indivisible-unbreakable”

Physical Science CHEMICAL BONDS. Atomic Models in History Democritus, Greek philosopher, around 400 BC used the term “atomos” which means “indivisible-unbreakable”

Basic Chemistry Atoms, Elements & Molecules. Atoms Around Us “To understand the very large, we must understand the very small” Democritus Atoms Atomos.

Basic Chemistry Atoms, Elements & Molecules. Atoms Around Us “To understand the very large, we must understand the very small” Democritus Atoms Atomos.

1 Chapter 5 Atoms, Molecules, and Ions 2 History n Greeks n Democritus and Leucippus - atomos n Aristotle- 4 elements. n Alchemy-experimentation n 1660.

1 Chapter 5 Atoms, Molecules, and Ions 2 History n Greeks n Democritus and Leucippus - atomos n Aristotle- 4 elements. n Alchemy-experimentation n 1660.

1.cdn.edl.io · Web viewBasic Overview of Atomic Theory Atomic Theory – History Democritus – “ Atomos ” – indivisible particles Lavoisier – Law of Conservation of Mass/Matter

1.cdn.edl.io · Web viewBasic Overview of Atomic Theory Atomic Theory – History Democritus – “ Atomos ” – indivisible particles Lavoisier – Law of Conservation of Mass/Matter

Atomic Theory-Democritus Greek philosopher, 400 BC Greek philosopher, 400 BC Named the smallest piece of matter “atomos,” meaning “not to be cut.” Named.

Atomic Theory-Democritus Greek philosopher, 400 BC Greek philosopher, 400 BC Named the smallest piece of matter “atomos,” meaning “not to be cut.” Named.

History of the Atom. Democritus (400 BC) Proposed that matter was composed of tiny, invisible particles. Gr. atomos.

History of the Atom. Democritus (400 BC) Proposed that matter was composed of tiny, invisible particles. Gr. atomos.

II. History of atomic structure A. Democritus – 500 BCE Theorized that matter is composed of small, indivisible particles = ATOMOS (Greek for indivisible)

II. History of atomic structure A. Democritus – 500 BCE Theorized that matter is composed of small, indivisible particles = ATOMOS (Greek for indivisible)

The History of Atomic Structure. Democritus Named the atom from the Greek word “atomos” meaning indivisible. Wrote that atoms were the smallest unit.

The History of Atomic Structure. Democritus Named the atom from the Greek word “atomos” meaning indivisible. Wrote that atoms were the smallest unit.

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

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

Atoms and the Periodic Table The Atom Ch. 4. Democritus (400 BC) Greek philosopher. All things are composed of tiny, indivisible particles: called: Atomos.

Atoms and the Periodic Table The Atom Ch. 4. Democritus (400 BC) Greek philosopher. All things are composed of tiny, indivisible particles: called: Atomos.

Chapter 2 (Part I) Atoms, Molecules, and Ions History n Greeks n Democritus and Leucippus - atomos n Aristotle- elements n Alchemy n 1660 - Robert Boyle-

Chapter 2 (Part I) Atoms, Molecules, and Ions History n Greeks n Democritus and Leucippus - atomos n Aristotle- elements n Alchemy n 1660 - Robert Boyle-

Atomic Structure Chapter 5 The Atomists: The first atomic theory 460 BCE: Greek Democritus suggested that matter is “ composed of minute, invisible,

Atomic Structure Chapter 5 The Atomists: The first atomic theory 460 BCE: Greek Democritus suggested that matter is “ composed of minute, invisible,

Atomic Structure The Idea of the Atom Early Models Greek philosophers – 450 B.C. what is the smallest particle? Democritus - Particles are atomos An.

Atomic Structure The Idea of the Atom Early Models Greek philosophers – 450 B.C. what is the smallest particle? Democritus - Particles are atomos An.

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

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

Chapter 2 Atoms, Molecules, and Ions History n Greeks n Democritus and Leucippus - atomos n Aristotle- elements n Alchemy n 1660 - Robert Boyle- experimental.

Chapter 2 Atoms, Molecules, and Ions History n Greeks n Democritus and Leucippus - atomos n Aristotle- elements n Alchemy n 1660 - Robert Boyle- experimental.

Chapter 4 The Structure of the Atom. Chapter 4 Democritus: Greek philosopher coined the word “atom”. Greek word comes from “atomos” meaning indivisible.

Chapter 4 The Structure of the Atom. Chapter 4 Democritus: Greek philosopher coined the word “atom”. Greek word comes from “atomos” meaning indivisible.

Chapter 2 Notes Atomic Structure. Atoms Democritus – Ancient Greek Science dude, 1 st proposed the idea of atoms, tiny indivisible particles Atomos –

Chapter 2 Notes Atomic Structure. Atoms Democritus – Ancient Greek Science dude, 1 st proposed the idea of atoms, tiny indivisible particles Atomos –

PreAP Chemistry Chapter 3. Democritus was the early Greek philosopher who is credited with the concept of the atom (atomos) –which means invisible.

PreAP Chemistry Chapter 3. Democritus was the early Greek philosopher who is credited with the concept of the atom (atomos) –which means invisible.

Electrons in Atoms. Democritus (400 B.C.) Proposed that matter was composed of tiny indivisible particles Not based on experimental data Greek: atomos.

Electrons in Atoms. Democritus (400 B.C.) Proposed that matter was composed of tiny indivisible particles Not based on experimental data Greek: atomos.

Chapter 2 Atoms, Molecules, and Ions. History Greeks Greeks Democritus and Leucippus - atomos Democritus and Leucippus - atomos Aristotle- elements Aristotle-

Chapter 2 Atoms, Molecules, and Ions. History Greeks Greeks Democritus and Leucippus - atomos Democritus and Leucippus - atomos Aristotle- elements Aristotle-