Big Idea #8: Properties of Matter Big #1: Nature of Science Essential Content: Atoms, Elements, & Theories in Science Illustration From October 2011 Issue of Scientific American “Atom Power” Article

Key Concepts for this Unit Neutral, atom, model, molecule, element, proton, neutron, electron, nucleus, energy level, electron cloud, solid, liquid, gas, state, phase, kinetic energy, change of state, melting, freezing, evaporation, vaporization, condensation, sublimation, subatomic particle, atomic theory, atomic number, mass number, atomic mass.

Daily Objectives: Describe the development of the current model of the atom. Illustrate how and why the model of the atom has changed over time. Differentiate between the building blocks of matter the atom and building blocks of life the cell.

Essential Questions: 1. How did Democritus describe atoms? 2. How did John Dalton further Democritus’ ideas on atoms? 3. What instruments are used to observe individual atoms?

“Would you find it difficult to believe in something you couldn’t see? Using your unaided eyes, you cannot see the tiny fundamental particles that make up matter. Yet all matter is composed of such particles, which are called atoms. An atom is the smallest particle of an element that retains its identity in a chemical reaction” (Wilbraham, Staley, & Matta, 2005).

Definition of an Atom An atom is the smallest particle of an element that retains its identity in a chemical reaction. Because chemical reactions produce a substance with a new identity (new physical and chemical properties), when atoms of the same kind combine to form elements, the same thing occurs—a new product is formed.

Class Notes: Who was Democritus? How is he involved with the atom? He was a Greek philosopher who started the discovery of the atom by claiming that they were the indivisible building block of matter.

Who is John Dalton? John Dalton continued Democritus’ research by developing the Atomic Theory. This theory is based off the 4 “rules” that all atoms follow.

Class Notes: Dalton’s Atomic Theory 1. All elements are made up of atoms that are indivisible. 2. Atoms of the same element are identical. 3. Atoms of different elements combine in ratios to form compounds. 4. Atoms of one element can never turn into another element’s atom.

Instrument Used to See the Atoms This is called a Scanning Tunneling Microscope Electron micrographs showing inactive (left) and active (right) catalysts consisting of gold particles absorbed on iron oxide. The red circles indicate the presence of individual gold atoms. The yellow circles show the location of subnanometer gold clusters that can effectively catalyze the conversion of carbon monoxide to carbon dioxide. One nanometer is about half the size of a DNA molecule. (Color added for clarity) (Credit: Lehigh University Center for Advanced Materials and Nanotechnology)

CW: History of the Atom Review Part 1: Answer questions 1 &2 from the notes 1. Who is Democritus and how is he involved with the history of the atom? 2. Explain John Dalton’s contribution to the science of the atom. Part 2: Read pgs in your Reading Essentials Wkbk. Answer Reading Check questions #3, 4, 5, & 6