Section 2: Atomic Discoveries

Slides:

Advertisements

Similar presentations

Advertisements

Chapter 4 Atomic Structure

ATOMIC STRUCTURE AND HISTORY

Section 4.1 & 4.2 Defining the Atom & Structure of the Nuclear Atom

Subatomic Particles What are three kinds of subatomic particles? 4.2

Chapter 4 Atomic Structure 4.2 Structure of the Nuclear Atom

Unit 3 Atomic Structure 4.2 Structure of the Nuclear Atom

THE ROAD TO THE ATOM.

The History of the Atom.

Atomic Theory and the Atom

Chapter 4 Atomic Structure

The Gold Foil and the Nucleus

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, Section 2 Sub-Atomic Particles and Nuclear Atoms.

Structure of the Nuclear Atom

Early Theories & Subatomic Particles ( )

History of 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.

SCH4C UNIT 1: Matter and qualitative Analysis Atomic Theory

Atomic Structure.

Subatomic Particles Dalton, Democritus & other early chemists thought the atom was a homogeneous particle. Static electricity between objects made scientists.

The Parts of an Atom.

Chapter 4: Atomic Structure

EARLY Atomic theories.

Discovery of the Atom. Democritus  Democritus was an ancient Greek who had a philosophical idea of an atom.  His approach was not based on the scientific.

The History of the Atom…. went against, Aristotle, who believed that matter was composed of four qualities: earth, fire, air and water all matter is composed.

Atomic Theory “History of... ”. The Ancient Greeks Democritus and other Ancient Greeks were the first to describe the atom around 400 B.C. The atom was.

Atomic Theory. The Atom Recall the atom is the smallest particle making up an element.

Section Structure of the Nuclear Atom Cathode-ray tubes are found in TVs, computer monitors, and many other devices with electronic displays. 3.

Atomic Model History.

Chapter 4 Atomic Structure

Section 4.2 Defining the Atom.

The Structure of the Atom

History of Atomic Theory from Democritus to Rutherford

Ch. 4.2 Structure of the Nuclear Atom

3-2 Radioactivity and the nucleus (10.2 pg )

Atomic Structure.

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.

The Atomic Theory Democritus Dalton 440 B.C. – Thought matter was made of tiny particles – Believed these particles could not be cut into anything smaller.

Chapter 2-2 Atoms and Elements

Chapter 11 Introduction to Atoms. Section 1: Objectives  Describe some of the experiments that led to the current atomic theory.  Compare the different.

1.3 Early Models of the Atom pp Ancient Models of the Atom Democritus: he stated that there must be a smallest particle, which he called an.

The Changing Model of the Atom

Atomic Theory Democritus to Rutherford. Democritus - Ancient Greece w Philosophical question: Could matter be divided into smaller and smaller pieces.

Structure of an Atom Nucleus: Nucleus:Proton.

Slide 1 of 25 Chemistry 4.2. © Copyright Pearson Prentice Hall Slide 2 of 25 Structure of the Nuclear Atom Cathode-ray tubes are found in TVs, computer.

+ ATOMIC THEORY. + Democritus Atom He was said to be the first step toward the current atomic theory. Hypothesized all matter is composed of tiny particles.

Historical Development of an Atom. Democritus B.C Democritus was a Greek philosopher ( B.C.) who is the father of modern atomic thought.

The Atom - Scientists. Philosophers Democritus – believed matter was not infinitely divisible THERE WERE NO EXPERIMENTS TO TEST HIS IDEAS Matter is composed.

Subatomic Particles protons, neutrons and electrons.

THE STRUCTURE OF THE ATOM.  All atoms consist of 2 regions:  1) Nucleus: very small region located near the center of the atom  Proton: positively.

Ch 5: Atomic Structure. warmup All matter is composed of very small particles called atoms. In middle school science you learned about the atom. 1. Draw.

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.

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.

End Show © Copyright Pearson Prentice Hall Slide 1 of 25 Structure of the Nuclear Atom Cathode-ray tubes are found in TVs, computer monitors, and many.

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.

Ch. 3-2 Structure of the Nuclear Atom

Atomic Structure Scale of the Universe.

Chapter 4 Atomic Structure 4.2 Structure of the Nuclear Atom

Evolution of the atomic model

UNDERSTANDING THE PROPERTIES OF ELEMENTS

Section Structure of the Nuclear Atom

Atomic Theory The idea that matter is made up of atoms, the smallest pieces of matter.

Ch. 3-2 Structure of the Nuclear Atom

Presentation transcript:

Section 2: Atomic Discoveries Chapter 4: Atoms and Elements Section 2: Atomic Discoveries

Learning Goals Explain how the experiments of Thomson, Rutherford, and Chadwick led to the development of the nuclear theory of the atom. Describe early atomic models.

Solid Sphere Solid Sphere Model: Democritus Dalton

J. J. Thomson J. J. Thomson (1856–1940) In 1897, Thomson performed his famous cathode-ray tube experiments.

J. J. Thomson Electricity was passed through a vacuum sealed tube. When charged plates were brought close to the tube, the beam of electricity reacted. Moved towards the positively charged plate Moved away from the negatively charged plate

J. J. Thomson Based on his experiments, Thomson discovered the following: Electrons are negatively charged. Electrons are much smaller and lighter than atoms.

J. J. Thomson Electrons are uniformly present in many different kinds of substances. He proposed that atoms must contain positive charge that balances the negative charge of electrons.

J. J. Thomson Plum Pudding Model J.J. Thomson Negatively charged electrons were held in a sphere of positive charge

Ernest Rutherford Ernest Rutherford (1871-1937) In 1909, Rutherford performed his famous gold foil experiment.

Ernest Rutherford Tiny particles called alpha-particles were directed at a thin sheet of gold foil. Most particles passed straight through the foil, but some were deflected at large angles.

Ernest Rutherford Expected result of Rutherford’s gold foil experiment: If the plum pudding model were correct, the alpha- particles would pass right through the gold foil with minimal deflection.

Ernest Rutherford Actual result of Rutherford’s gold foil experiment: A small number of alpha- particles were deflected or bounced back.

Ernest Rutherford Based on his experiments, Rutherford discovered the following: Most of the atom’s mass and all of its positive charge are contained in a small core called the nucleus.

Ernest Rutherford Most of the volume of the atom is empty space through which the tiny, negatively charged electrons are dispersed. The number of negatively charged electrons outside the nucleus is equal to the number of positively charged particles (protons) inside the nucleus, so that the atom is electrically neutral.

Ernest Rutherford Planetary Model Ernest Rutherford A small, dense positively charged nucleus is orbited by electrons.

James Chadwick James Chadwick (1891-1974) In 1919, Chadwick and his mentor, Rutherford, kept finding that the atomic mass of an atom was larger than the atomic number of that atom.

James Chadwick Chadwick suggested that there could be an additional particle in the nucleus that had mass, but no charge. These particles were called neutrons

James Chadwick Nuclear Model Ernest Rutherford James Chadwick 99.9% of the atoms mass is concentrated in a small dense nucleus that contains protons and neutrons.

James Chadwick The dense nucleus makes up more than 99.9% of the mass of the atom but the nucleus occupies only a small fraction of an atoms volume The electrons are distributed through a much larger region but don’t have much mass.

James Chadwick A single grain of sand composed of solid atomic nuclei would have a mass of 5 million kg. Astronomers believe that black holes and neutron stars are composed of this kind of incredibly dense matter.