History of the Atom.

Slides:



Advertisements
Similar presentations
The History of the Atom.
Advertisements

History of Atomic Structure
Unit: Atomic Structure
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.
Introduction to Atomic Structure Chemistry Chemistry is the study of matter and the changes it undergoes. The type of matter that is changing and what.
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.
Chapter 3: Discovering the Atom and Subatomic Particles
Atomic Structure. Early Theories of Matter Democritus ( BCE) Democritus ( BCE) Greek philosopher Greek philosopher First to propose the.
Section 4.2 Defining the atom. The Atom What we know now: Definition: Atoms are the smallest particle of an element that retains the properties of that.
History of Atomic Theory
Atomic Structure.
History of Atomic Theory
Ch. 3-2 Structure of the Nuclear Atom
History of Atomic Theory
Atom Definition: the smallest particle of any element that retains the properties of that element.
Atomic History and Theories
Atomic Structure.
1803 John Dalton Father of the Modern Atomic Theory
4.1 NOTES The History of the Atom
THE ATOM.
Atomic Theory “History of. . . ”.
Chapter 4 The Structure of the Atom
Early Models of the Atom
Atomic Theory Label the 3 different particles that make up an atom
Scientists and Their Contribution to the Model of an Atom
Atomic History and Theories
1803 Key words John Dalton Father of the Modern Atomic Theory.
The Atom.
Structure of the Atom Chapter 4.
Old Dead Guys.
Chapter 4 Atomic Structure 4.2 Structure of the Nuclear Atom
Unit 2: Atomic Theory & Structure
Chapter 5 Atomic Structure and the Periodic Table
Atomic Structure (History & Background
The Development of the Atomic Theory
History of Atomic Theory
SCH3U Unit 1: Matter, Chemical Trends and Chemical Bonding
1.3 History of the Atom Objectives 3:a,c,d; 5
Atom Model History - Democritus a fifth century B.C. Greek philosopher proposed that all matter was composed of indivisible particles called atoms (Greek.
Warm-Up Draw a picture of an atom. Be as specific as you can!
History of Atomic Theory
ATOMIC HISTORY & ISOTOPES
Atomic Theory.
Chapter 3- Atomic Structure
1.3 Atomic Theory.
Atomic Theory.
Discovery of the Atom.
Who am I?.
Questions to answer: 1) What were the ancient elements?
BELLWORK 9/11/17 What is the atom?
Atomic Structure Ch. 4.
The History of the Atom.
Research Hypothesis Theory An educated guess based on an observation
Early History of the Atom
Development of Atomic Structure
The Building Blocks of Matter
Atomic history.
4.1 & 4.2 Early Theories & Subatomic Particles
The atom Chapter 4.
Atomic Structure Chp 4.
History of the atomic model (Part 1)
Atomic Structure An atom is the smallest particle of an element that retains its identity in a chemical reaction. Although early philosophers and scientists.
Development of Atomic Structure
SCH3U Unit 1: Matter, Chemical Trends and Chemical Bonding
Atomic Structure N5.
Ch. 3-2 Structure of the Nuclear Atom
Atomic Structure N5.
Honors Coordinated Science II Wheatley-Heckman
Presentation transcript:

History of the Atom

Compare and contrast the major models of the atom. Interpret the periodic table to describe an element’s atomic makeup.

John Dalton

John Dalton The Atom 1808 Studied chemical reactions and mass ratios Concluded that… Matter is composed of extremely small particles Atoms are indivisible and indestructible Atoms of a given element are identical in size, mass and properties Atoms of a specific element are different from those of another element

Dalton – Model of the Atom Dalton’s Model of the Atom is called the Solid Sphere Model

Dalton – Model of the Atom Now, what does this look like? Draw Dalton’s atomic model for hydrogen and oxygen Hydrogen Oxygen

Where did Dalton go wrong? Are atoms indivisible? No – atoms are made of smaller parts – protons, neutrons, & electrons Do atoms of the same element always have identical mass? No – isotopes same # p different #n  different mass Example: Ne – 20 & Ne- 22 Do atoms of the same element always have identical properties? No – allotropes Same element but different properties Example: diamond, coal, graphite

JJ Thomson – The Electron 1897

JJ Thomson – Cathode Ray Tube Used a Cathode-Ray Tube What is a vacuum? An enclosed space from which matter, esp. air, has been partially removed so that the matter or gas remaining in the space exerts less pressure than the atmosphere. Cathode-Ray Tube Tube with a vacuum inside Connect to anode & cathode power supply – electricity running through the tube

Cathode Ray Tube

Discovering Electrons Cathode ray deflected away from the negative pole of the magnetic field Since the rays were deflected away from a negatively charged object, the ray must also be NEGATIVE FOUND THE ELECTRONS – the negatively charged subatomic particle Studied charge-to-mass ratios The mass of the electrons is 2000 times smaller than the mass of a H atom

Plum Pudding Model What would Thomson’s model look like? Draw Thomson’s model of the atom for hydrogen and oxygen.. Hydrogen - 1 e- Oxygen – 8e-

Plum Pudding Model What element is represented in the plum pudding model shown? What would the overall charge of the particle be?

What is next? After Thomson, scientists inferred: Atoms must contain a positive charge. WHY? The overall charge of the atom is not negative bc net charge = 0 Atoms must contain other particles (regardless of charge). Electrons do not account for the entire mass of the atom

Ernest Rutherford positive proton dense positive nucleus Atom is mostly empty space 1911

Gold Foil Experiment Shot a beam of positively charged alpha particles at a piece of gold foil Expected the positive particles to pass through with little deflection

What Rutherford expected to see...

What Rutherford ACTUALLY observed

Gold Foil Experiment

What actually happened? Most particles passed through with no deflection Most of the atom is EMPTY SPACE Some particles were slightly deflected The atom contains negative electrons 1/8000 particles were deflected back towards the source Some positive alpha particles came near positive particles in the atom  densely packed protons

Rutherford’s Conclusion the atom is mostly empty space with a dense positively charged nucleus Still a problem though…Rutherford’s conclusion doesn’t account for the entire mass of the atom.

James Chadwick Discovered the neutron helped explain & account for the mass of the atom 1932

space surrounding nucleus Subatomic Particles Particle Symbol location in atom charge relative mass actual mass (g) electron e- space surrounding nucleus 1- 1/1840 9.11x10-28 proton p nucleus 1+ 1 1.673x10-24 neutron n 1.675x10-24

Nuclear Model of the Atom For the sake of simplicity when referencing the “Rutherford Model” we will include James Chadwick’s contribution as well. Steps in drawing Rutherford’s model: Determine the number of protons, neutrons and electrons in the atom Draw the nucleus with protons & neutrons Draw the electrons randomly around the outside of the nucleus

Nuclear Model Hydrogen Oxygen p+=1 n0=0 e-=1 p+=8 n0=8 e-=8 We are now going to draw the Rutherford/Chadwick Models for the elements in the table Do they give you any reason to think they are changed? NO – assume they are neutral  p=e Hydrogen Oxygen p+=1 n0=0 e-=1 p+=8 n0=8 e-=8 p=1 n=0 p=8 n=8

Summary Dalton Thomson Rutherford Started studying the atom & chemical reactions Mostly wrong Thomson Electrons Cathode Ray Tube Plum Pudding Model Rutherford Protons Gold Foil Experiment Model combined with Chadwick (neutrons)