If we can’t see atoms, how do we know they exist? What are atoms? Do now Agenda Do Now Objectives Intro to Atoms Science of atoms Parts of the atom Redesigning the Atom Closing Please take 2 minutes to answer these: If we can’t see atoms, how do we know they exist? What are atoms?

Objectives By the end of today, you will be able to: Content: Agenda Do Now Objectives Intro to Atoms Science of atoms Parts of the atom Redesigning the Atom Closing By the end of today, you will be able to: Content: Compare the different ways (theories) of understanding atoms (matter) Language: Describe the steps (people) that were required to figure out the current understanding of atoms.

Together http://www.bbc.co.uk/schools/gcsebitesi ze/science/add_aqa_pre_2011/atomic /atomstrucact.shtml After the video clip, make sure you ask me at least 1 good question!!! Sample project from student

History of Atomic Theory Introduction: in the past…!

What are atoms? Agenda Do Now Objectives Intro to Atoms Science of atoms Parts of the atom Redesigning the Atom Closing Atoms are… Just how small are they? 1 cm3 of air = 45 000 000 000 000 000 000 atoms

Why do we care so much about atoms? Agenda Do Now Objectives Intro to Atoms Science of atoms Parts of the atom Redesigning the Atom Closing ATOMS MAKE UP ALL MATTER! So… the more we can understand atoms, what they look like, and how they behave, the more we can understand the world around us.

Key question Who were the first people to think about the atom (this is a trick question – really think about it)?

Democritus – A Philosophy of Atoms Part One Democritus – A Philosophy of Atoms

First Atomic Theory WRONG! Agenda Do Now Objectives Intro to Atoms Science of atoms Parts of the atom Redesigning the Atom Closing Think that it was fancy scientists with fancy equipment that discovered atoms? WRONG! Some of the first people to think about atoms were actually early Greeks!

Early Greek Philosophers Democritus Everything is made of small, indivisible, atoms. Not just matter – space and time too!!! Atoms never change, but they combine to make different substances. Different atoms have different shapes, sizes, and temperatures.

Properties of Atoms Small, pointy atoms  Solids Agenda Do Now Objectives Intro to Atoms Science of atoms Parts of the atom Redesigning the Atom Closing Small, pointy atoms  Solids Large, round atoms  Liquids Sharp Atoms  Bitter Taste Round Atoms  Sweet Taste

Key question What was wrong with the Greek view of the atoms?

Part 2 The Science of Atoms

Antoine Lavoisier French chemist, 1700’s. Agenda Do Now Objectives Intro to Atoms Science of atoms Parts of the atom Redesigning the Atom Closing French chemist, 1700’s. Executed during the French Revolution! One of the first people to quantitatively study chemistry! Didn’t do a whole lot of work investigating atoms, but he set the path for scientifically studying chemistry.

John Dalton English Chemist and Physicist, 1800’s. Agenda Do Now Objectives Intro to Atoms Science of atoms Parts of the atom Redesigning the Atom Closing English Chemist and Physicist, 1800’s. Humble, independent, awkward. First scientific atomic theory. 1808: “A New System of Chemical Philosophy” Work on colorblindness (“Daltonism”) Welcomed into the Royal Society 40 000 in funeral procession

Dalton’s Model of the Atom – Nothing New? Agenda Do Now Objectives Intro to Atoms Science of atoms Parts of the atom Redesigning the Atom Closing

Playing with Gas Dalton became famous by mixing gases and taking down observations… Lots and lots of observations! Dalton took over 200 000 observations of gases reacting with each other.

Dalton’s Experiment Oxygen Water Hydrogen

Dalton’s Experiment Carbon Hydrogen Agenda Carburetted Hydrogen Do Now Objectives Intro to Atoms Science of atoms Parts of the atom Redesigning the Atom Closing Carbon Carburetted Hydrogen Hydrogen

Dalton’s Experiment Hydrogen Nitrogen Agenda Ammonium Do Now Objectives Intro to Atoms Science of atoms Parts of the atom Redesigning the Atom Closing Hydrogen Ammonium Nitrogen

Nitrous Gas Nitric Acid Oxygen Nitrous Gas Nitrous Acid Oxygen Agenda Do Now Objectives Intro to Atoms Science of atoms Parts of the atom Redesigning the Atom Closing Oxygen Nitrous Gas Nitrous Acid Oxygen

What does it all mean? Agenda Do Now Objectives Intro to Atoms Science of atoms Parts of the atom Redesigning the Atom Closing “Why does not water admit its bulk of every kind of gas alike? This question I have duly considered, and though I am not able to satisfy myself completely I am nearly persuaded that the circumstance depends on the weight and number of the ultimate particles of the several gases.” Absorption of Gases, 1805

Dalton’s “Atomism” All matter is composed of extremely small particles called atoms. All atoms of a given element are identical, having the same size, mass, and chemical properties. Atoms of a specific element are different from those of any other element. Atoms cannot be created, divided into smaller particles, or destroyed. Different atoms combine in simple whole-number ratios to form compounds. In a chemical reaction, atoms are separated, combined, or rearranged.

Dalton’s Atomism (true/false) All matter is composed of extremely small particles called atoms.

Dalton’s Atomism (true/false) 2. All atoms of a given element are identical, having the same size, mass, and chemical properties. Atoms of a specific element are different from those of any other element.

Dalton’s Atomism (true/false) Agenda Do Now Objectives Intro to Atoms Science of atoms Parts of the atom Redesigning the Atom Closing 3. Atoms cannot be created, divided into smaller particles, or destroyed. “We may as well attempt to introduce a new planet into the solar system or annihilate one in existence, as to create or destroy a particle of hydrogen.”

Dalton’s Atomism (true/false) Agenda Do Now Objectives Intro to Atoms Science of atoms Parts of the atom Redesigning the Atom Closing 4. Different atoms combine in simple whole- number ratios to form compounds. Atoms mix together to make molecules. Can only mix whole numbers of atoms. All of Dalton’s gas experiments helped him figure out what elements different molecules were made of.

Dalton’s Atomism (true/false) 5. In a chemical reaction, atoms are separated, combined, or rearranged.

Did everyone believe Dalton? Agenda Do Now Objectives Intro to Atoms Science of atoms Parts of the atom Redesigning the Atom Closing No! Many scientists didn’t believe in “atomism.” Ernst Mach – famous physicist Thought that since you can’t actually watch and observe atoms, that Dalton’s theory was unscientific.

NECAP Q Agenda Do Now Objectives Intro to Atoms Science of atoms Parts of the atom Redesigning the Atom Closing

Which model demonstrates the Law of Conservation of Matter?

With a partner One of you please talk how the Greeks understood the atom The other person, please discuss how Dalton understood the atom Between the two of you, please discuss what was wrong with each “model” (theory).