Atomic Theory Mr. Tollefson Chemistry Class. Introduction Students will be introduced to the atom and the development of the atomic theory from ancient.

Slides:

Advertisements

Similar presentations

A History of the Atom A long time to study a little thing.

Advertisements

Atomic Theories.

Section 4.1—Development of Atomic Theory

Atomic Structure. What is an Atom? The smallest part of an element.

Early Greeks to Present

THE ROAD TO THE ATOM.

Atomic Theory “History of. . . ”.

Ancient Greece Democritus: .

The History of the Atom.

Atomic Theory and the Atom

Atomic Structure Timeline

Chpt. 2: The Atom.

Atomic Structure.

By: Amina Al-Naama 7D. An atom a fundamental piece of matter. Everything in the universe except energy is made of matter, and, so, everything in the universe.

Chapter 4: Glow in the Dark

Chapter 4 Atomic Structure.

Atomic Structure and The Periodic Table

Chapter 4: Glow in the Dark

HW for Next Class:  Read pages  Worksheet: 5.2 (Structure of Nuclear Atom)  Quiz: Next time.

History of Atomic Theory

History of Atomic Structure

Unit: Atomic Structure

Chemistry Sheds Light on Our Lives Unit 4 Atoms and Light

Chapter 4: Discovery of Atomic Structure. Prentice Hall © 2003Chapter 2 The Discovery of Atomic Structure An ancient Greek named Democritus was the first.

PART ONE ATOMIC THEORY. Over the course of thousands of years our idea of what matter is made of and what the atom looks like has changed dramatically.

+ HAPPY HUMP DAY!!! Homework DUE now! Get ready for your element quiz!!! TEST TOMORROW chem nerds… STUDY!!!

Chapter 4: Atomic Structure

Atomic Structure.

Atomic Structure History and Theories. The Greeks 4 th century B.C. Democritus “Atomists” school of thought Matter is composed of tiny indivisible particles.

TITLE The Development of Atomic Theory. Early Ideas Democritus—Greece 400 B.C. His idea:  There was a limit to how far you could divide matter. You would.

NOTES – Introduction to Atomic Theory ( )

Atomic Theory: the beginning Chapter 3 Part I. Democritus An Ancient Greek Theorized about the existence of atoms. Did not use Scientific Method.

Atomic Structure. Way Early Theories Democritus ( BC) –First person to propose that matter is not infinitely divisible –Atomos –Matter is empty.

The Changing Models of the Atom

Atomic Theory 15,000 kilotons.  Dismissed idea of the atom. Early Greeks Two schools of thought:  Matter is made of indestructible particles called.

Atomic Structure. 1. Democritus: Around 300 BC, a Greek philosopher, Democritus stated that everything is made up of tiny, invisible particles He said.

Slide 1 of 18 © Copyright Pearson Prentice Hall Defining the Atom > Atomic Structure Chapter 4 Video 3.

1 The Atom, in a nutshell…. 2 Democritus (c. 460—370 BC) Greek philosopher  The name atom was his idea  Proposed matter is made up of small particles.

History of the Atom. What do you know about the atom? Put simply, the atom is the smallest particle of pure essence. For example, helium gas is made up.

Chapter 5 Notes Atomic Theory As Seen Through History.

The Chemical Behavior of Atoms Day 1. Curriculum  Big Idea: Atomic theory is the foundation for the study of chemistry.  Concept: Energy is absorbed.

Atomic Structure.

Solid, homogeneous, indestructible and indivisible (400 BC)

Do Now: Solve the following using the correct number of significant figures. 1)7.76 m m = 2)5.750 cg cg = 3)5555 kg kg = 4)1.23 m x 3.2.

Do Now: 1.On the blank side of an index card, draw a picture of an atom. 2.On the other side of the index card, write down things that you know about atoms.

Development of the Atom Chapter JOHN DALTON All matter is composed of atoms All atoms of a given element are identical Atoms of specific elements.

Scientists of Atomic Theory Unit 2 Democritus 460 B.C B.C. This Greek philosopher was among the first to suggest the existence of atoms. Democritus.

The Atom Chapters 4-5 Atomic Theories Democritus ~ 400 BC believed that atoms were indivisible and indestructible Dalton ~ 1800’s Developed through experiments.

The History of the Atom.

The Changing Model of the Atom

Brief History of Atomic Theory. 1 st atomic models In 400 BC, the model looked like a solid indivisible ball In 400 BC, the model looked like a solid.

Chemistry Chapter 4 Notes #1 09/10/10. Democritus Matter is composed of empty space where atoms move Atoms are solid, homogenous, indivisible, and indestructible.

Chapter 4. Atom Smallest particle of an element that retains its chemical identity Atoms of the same element cannot be separated chemically because they.

Models of the Atom. Ancient Greece 300 BC in Greece School of thought that matter is made up of tiny indivisible, invisible, indestructible, fundamental.

The Beginning of the Atomic Theory Democritus was a Greek philosopher who was among the first to suggest the existence of atoms. 460 BC – 370 BC.

Atomic Structure CHAPTER 4. Defining the Atom ✴ An atom is the smallest particle of an element that still has the chemical properties of that element.

Atomic Theorists and their Contributions

The Changing Model of the Atom From Democritus to Bohr.

Atomic Structure Section 4-1. Democritus Greek philosopher 4 th Century BC First to come up with “atom”. Matter is composed of tiny particles called atoms.

The Changing Model of the Atom. Aristotle 400 BCE claimed that there was no smallest part of matter different substances were made up of different proportions.

Atomic Theory Mr. Tollefson Chemistry Class. Introduction Students will be introduced to the atom and the development of the atomic theory from ancient.

1 The History of Atomic Theory A long and winding road Section 4.1.

Atomic Structure. Early Theories of Matter Democritus ( BCE) Democritus ( BCE) Greek philosopher Greek philosopher First to propose the.

Chapter 4: Glow in the Dark

Models of the Atom.

BELLWORK 9/11/17 What is the atom?

The Development of Atomic Theory

The atom Chapter 4.

Presentation transcript:

Atomic Theory Mr. Tollefson Chemistry Class

Introduction Students will be introduced to the atom and the development of the atomic theory from ancient times to the present day. It is your job to take notes on the pertinent information in this presentation.

The Atom Democritus, an Ancient Greek philosopher, first purposed the word ‘Atom’ around 375 BC. The atom was defined as a small round indivisible particle. Democritus described the atom by talking about the constant division of an object until the object could no longer be divided. The idea of the Atom had to wait for 2200 years to be proven.

Dalton and Atomic Theory John Dalton’s (d1844) Atomic Theory consists of 4 parts. It was the first departure from the ancient idea of the atom. Most of the elements of this theory are still true today.

Dalton and Atomic Theory –All elements are composed of indivisible particles called atoms. –Atoms of the same element are identical. Atoms of element are different from others. –Atoms can mix together in whole number ratios –Chemical reactions occur when atoms combine, separate or rearrange

Electron’s: Discovery 1897 The English physicist Sir JJ Thompson discovered the electron in He experimented with sealed tubes with gases in them. He passed high voltage electric current through the tubes. The glowing beam created is called a cathode ray.

Cathode Rays Thompson thus created CRT’s or Cathode Ray Tubes, the basis for televisions and computer monitors. Thompson found that the rays were attracted to metal plates that carry positive charges. Thompson proposed that a cathode ray is composed of tiny negatively charged particles about 1/2000 the mass of the hydrogen atom. He called them electrons.

Plum Pudding Thompson also worked with modified cathode ray tubes that gave rays traveling in the opposite direction. These particles were found to have the same amount of charge as electrons, just the opposite sign. These were later called protons.

PLUM PUDDING From what Thompson learned about protons and electrons he proposed his ‘Plum Pudding’ model of the atom. Protons and electrons are mixed together in a big blob with no particular order.

Nucleus Ernst Rutherford made a major advance in atomic theory with a simple experiment with complex results (1912). Sometimes called the ‘gold foil experiment’ it is the foundation of the modern atom.

Radioactive Source Gold Foil Phosphorescent Screen Alpha Radiation Diagram for gold foil experiment Deflected radiation

GOLD FOIL EXPERIMENT Using a radioactive source Rutherford fired alpha particles at a very thin piece of gold foil. He expected the alpha particle to easily pass through the foil and strike the screen on the opposite side. He found that some of the particles were deflected at small angles and some were reflected straight back.

Nucleus The results of Rutherford’s experiment was his proposal of the nuclear atom. He proposed that in the center of an atom was a very small and dense ‘nucleus’ and that the nucleus was composed of protons.

Rutherford Atom The electrons in the Rutherford atom hold no specific place in the atom, they are free to move about. So, the Rutherford model of the atom has a small dense nucleus with free roaming electrons.

BOAR? BOOR? BOHR? BAOR Neils Bohr worked with Lord Rutherford for a short while and came up with his own hypothesis for the structure of an atom. It is called the planetary model of the atom.

Planetary Atom The only difference between the planetary atom and the Rutherford atom is the placement of the electrons in orbitals. Electrons can only occupy specific orbits at specific energy levels around an atom. The farther away an electron is from the nucleus the higher it’s energy state.

Planetary atom Electrons in orbit, nucleus at center. Electrons = 2n 2

The Modern Atom Today’s atom is very similar to the Bohr atom. The modern atom is sometimes called the quantum mechanical atom. That is because the theory was based on a type of physics called quantum mechanics.

Quantum Mechanics Todays Atom is only different from Bohr’s Atom in that it does not actually occupy orbits. It has a probability of occupying certain places around the atom and 90% of the time it spends in the ‘Bohr Orbits’. The position of the electron is determined by it’s energy.

Schrodinger The main mathematics for the quantum atom were performed by Erwin Schrodinger in the 20’s and 30’s. The equation that describes the position of an electron around an atom is called Schrodinger’s Equation and deals in differential calculus.

Neutron The Final sub-atomic particle was found in the 1930’s by James Chadwick. He proposed this particle had no charge but was as massive as the proton and also resided in the nucleus. He called it the neutron, after it’s neutral charge.

Today Today we think there are sub-sub- atomic particles called ‘quarks’. Each Proton, neutron and electron is made up of 3 quarks. Quarks come in many different types and have partial charges of 2/3 and -1/3. Quarks also have other properties named, strangeness, charm, flavor, and color.