Warm-Up: Atom ProbeClasswork: Atom notes; Create a Timeline

Homework: The Atoms Family Album (Glue In)

All matter is composed of particles called atoms.small, fast

movingCombination of thousands of individual theories that provide evidence

Scientists rely Scientists rely upon models to upon models to help us to help us to understand the understand the atom.atom.

Believe it or not this is a Believe it or not this is a microscope. microscope.

May not always look like the actual object

Attempts to use familiar ideas to describe unfamiliar things in a visual way.

This is a painting of a This is a painting of a young woman by Pablo young woman by Pablo

Picasso. Does it actually Picasso. Does it actually look like a young look like a young

woman?woman?

The model above represents the most modern version of the atom.

Many of the models that you have seen may look like the one below. It shows the parts and structure of the atom.

Gathered without being able to directly observe the object.

Each new bit of information gives us a better understanding of atoms.

As new information is collected. From the early Greek concept to the modern

atomic theory, scientists have built upon and modified existing models of the atom.

Today, you will make a visual representation of these changes over time ….

Who: Aristotle, Democritus When: More than 2000 years ago Where: Greece What: Aristotle believed in 4 elements: Earth,

Air, Fire, and Water. Democritus believed that matter was made of small particles he named “atoms”.

Why: Observation and inference explains the existence of everything.

Aristotle

Democritus

Who: European Scientists When: 800 – 900 years ago Where: Europe What: Their work developed into what is

now modern chemistry. Why: Trying to change ordinary

materials into gold.

Alchemic Symbols

Who: John Dalton When: 1808 Where: England What: Described atoms as tiny particles

that could not be divided. Thought each element was made of its own kind of atom.

Why: Building on the ideas of Democritus in ancient Greece.

John Dalton

Who: J. J. Thompson When: 1897 Where: England What: Thompson discovered that electrons were

smaller particles of an atom and were negatively charged.

Why: Thought an atom was like a jigsaw puzzle made of smaller pieces.

Future: Thompson knew atoms were neutrally charged, but couldn’t find the positive particle.

J. J. Thompson

Who: Ernest Rutherford When: 1911 Where: England What: Conducted an experiment to isolate

the positive particles in an atom. Why: Theorized that the atoms were mostly

empty space, but had a dense central core. Future: He knew that atoms had positive and

negative particles, but could not decide how they were arranged.

Ernest Rutherford

Who: Niels Bohr When: 1913 Where: England What: Proposed that electrons traveled in fixed

paths around the nucleus. Why: Bohr was trying to show why the negative

electrons were not sucked into the nucleus of the atom.

Future: Scientists still use the Bohr model to show the number of electrons in each orbit.

Niels Bohr

Who: James Chadwick When: 1932 Where: England What: Proposed that since electrons have almost no

mass, something besides the protons in the nucleus were adding to the mass.

Why: Chadwick was trying to show a neutral particle -- one with the same mass as a proton, but with zero charge. He called this particle a neutron.

Future: The discovery of the neutron led to discoveries relating to splitting an atom.

Who: Schrödinger, Born, Heisenberg When: 1920’s Where: Austria, German What: Electrons travel around the

nucleus in random orbits. Electrons travel so fast, they appear to form a “cloud” around the nucleus.

Why: No experiment can measure the position and momentum of an electron so mathematics and physics make models.

Must include a title. Must have accurate time intervals. Must include a spot for each of the 8 items. Must include a brief description of the model (in

your own words!!!). Must have a picture of the model (color is

preferred) for each item. Must be completed by the end of class. Must have rubric attached to the back with

names.