Flashbacks 1. A place where an earthquake originates is called the __________. A Epicenter B Starting point C Quake zone D Shaking place 2. When only a small part of the moon is visible, the moon may be in its A. first-quarter phase B.. waning-crescent phase C. new moon phase D. last-quarter phase

Flashbacks 3 Earth has seasons because A. the temperature of the sun changes B. Earth rotates on its axis C. Earth's axis is tilted as it moves around the sun D. the distance between Earth and the sun changes 4 During what moon phase can a lunar eclipse occur?  A. waxing gibbous B. first quarter C. new moon D. full moon

Flashbacks 5 Tides are caused mainly by A. Earth's rotation on its axis, causing water to move B. strong winds blowing water onto coasts C. differences in how much the sun pulls on the different parts of Earth D. differences in how much the moon pulls on different parts of the Earth

Learning Targets: I will model/describe the various stages of atomic theories.

Before We Continue A = Agree D= Deny Before A or D StatementAfter A or D 1. Early philosophers studied atoms by doing experiments. 2. Atoms are made of mostly empty space. 3. Neutrons have no charge 4. Electrons travel in very predictable paths around the nucleus. 5. All atoms of an element have the same number of protons and neutrons. 6. Atoms of one element can change into atoms of another element through radioactive decay. 7. Radioactive isotopes are too dangerous to be of any benefit to humans.

Describing the Unseen  Early philosophers didn’t try to prove their theories by doing experiments as scientists now do.

Before the “Discover”  Chemists were learning about matter and how it changes.

The Break Down  When these chemists in the western world found out that some substances couldn’t be broken down any further, they named these substances elements.  An element is a matter made of atoms of only one kind.  Example: Iron is an element made up of only iron atoms.

Timeline  Along with taking notes, you are to make a timeline of all the events involving the history of the atom model.  Make a line all the way across your paper.  On your line mark decades like in the example below. Make room for notes about important years: Names of the scientists that worked on the theories. Picture of the atom theory accepted at the time

Dalton’s Concept Early 1800’s  John Dalton, an English schoolteacher in the early nineteenth century, combined the idea of elements with the earlier theory of the atom.  He proposed the following ideas about matter: Matter is made up of atoms. Atoms cannot be divided into smaller pieces All the atoms of an element are exactly alike Different elements are made of different kinds of atoms.

Discovery of Electrons 1897  In 1897, J.J. Thompson, an English physicist,.  By repeating Crooke’s experiments and eventually came up with the concept of electrons.

 Electrons are negatively charged particles.  One of the more surprising discoveries that came from Thompson’s experiments was the evidence that particles smaller than the atom do exist.

Timeline John DaltonJ.J. Thompson

Rutherford’s Experiments 1906  In 1906, Ernest Rutherford and his co- workers began an experiment to find out if Thomson’s model of the atom was correct.

Expected Results Rutherford was certain he knew what the results of this experiment would be His prediction was that most of the speeding alpha particles would pass right through the foil and hit the screen on the other side.

The Model Fails The positively charged alpha particles were moving with such high speed that it would take a large positive charge to cause them to bounce back.

 Rutherford hypothesized that almost all the mass of an atom and all of it’s positive charge are crammed into an incredibly small region of space at the center of the atom, called the nucleus.  The nucleus is what makes up the center of an atom.  Eventually, his prediction proved true. Rutherford’s Model With a Nucleus 1920’s

 Scientists, later, identified the positive charges in the nucleus as protons.  A proton is a positively charged particle present in the nucleus of all atoms.  The rest of each atom is empty space occupied by the atom’s almost mass less electrons.

Rutherford’s New Model

Timeline John DaltonJ.J. ThompsonRutherford

The Neutron  Rutherford’s nuclear model was applauded among scientist. However, some data still didn’t fit.  It was proposed that another particle must be in the nucleus to account for the extra mass.  The particle was called the neutron.

The Neutron  The neutron has the same mass as a proton and is electrically neutral.  Proving the existence of neutrons was difficult through, because a neutron has no charge.

The Revised Model

Electron Cloud Model 1900’s  Electron Cloud - electrons travel in a region surrounding the nucleus.  This is the most current, accepted, model of the atom.

The blueprints of the modern atom:  There are two regions of the atom: 1. The Nucleus 2. Electron Cloud

The Nucleus  It contains two kinds of particles: 1. Protons (which have a positive charge) 2. Neutrons (which are neutral)

The Electron Cloud  The Electron Cloud contains electrons.  Electrons have a negative charge.

Timeline John DaltonJ.J. ThompsonRutherford ’s Electron Cloud Model= 

Size and Scale  Because all of the models are drawings for the eye to see, it is hard to comprehend how “vastly” an atom is spread out.

The Challenge  Now try and draw all of the stages the atom went through:  1800  1870  1896  1920  2000’s

The Challenge  Now try and draw all of the stages the atom went through:  1800 The singular ball  1870 The ball with nodes.  1896 The nucleus  1920 The nucleus, neutrons, and protons  The nucleus, neutrons, protons, and electron cloud.

Jigsaw  Individually, you will read and summarize the main points of the section you’ve been given (put these notes on a loose leaf sheet of paper).  Once you have done your research, you will share your findings with a group. Things to present to your group Important years. (Important for timeline) Names of the scientists. Short summary of what they did. Picture of the atom theory accepted at the time if presented in the chapter (look at figures). Picture of experiments – if they did any (look at figures).

Numbers 1. Pg 405 “A Model of The Atom” 2. Pg 407 “ Discovering Charged Particles” 3. Pg 408 “Rutherford’s Experiments” 4. Pg 410 “A Model with a Nucleus” 5. Pg 412 “Further Developments”