Transcript Slide 1
Warm-Up Fold your warm-up paper in half. Continue folding your paper in half as many times as possible. How many folds can you make? If you were cutting your paper instead of folding, predict how many times it could be cut in half. Democritus Ancient Greece – 440 BCE If you keep cutting a coin in half, eventually an “uncuttable” particle remains. - An atom (“atomos” in Greek means indivisible) The smallest particle into which an element can be divided and still be the same substance Discovering the Scale and Structure of Atoms How small is an atom? What’s inside an atom? Write-Pair-Share What do you already know about atoms? What is something you would like to know about atoms? How Small is an Atom? An average atom has a diameter of 0.00000003 cm! (three hundred-millionths of a centimeter) 50,000 atoms to equal the thickness of aluminum foil! 20,000,000,000,000,000,000,000 atoms in a penny! (twenty thousand billion billion) * Over 3 trillion times more atoms than people on Earth. If a penny were enlarged to the size of the continental U.S., each atom would only be the size of a ping-pong ball. What’s Inside an Atom? Atoms consist of protons, neutrons, and electrons. The Nucleus – the tiny, extremely dense region at the center of an atom (positively charged) Protons – positively-charged particles of the nucleus Neutrons – particles of the nucleus with no charge Atomic particles so small, they have their own unit Atomic Mass Unit (amu) – SI unit of mass for atomic particles Protons = 1 amu Neutrons = 1 amu What’s Inside an Atom? Outside the Nucleus – Electrons – negatively-charged particles in atoms - Located around the nucleus in electron clouds - So small that mass is considered 0 amu 1,800 times smaller than a proton/neutron Atoms have neutral charges because positive protons and negative electrons cancel out. - When an atom is charged because of a proton/electron imbalance – it’s called an ion Atomic Particles Protons – positively-charged particles of the nucleus Neutrons – Electrons – particles of nucleus with no charge (neutral) negatively-charged particles in electron clouds around the nucleus Just How Small is an Atom? TED Talk by Jonathan Bergmann Atomic Structure – PhET Simulation What’s in the Bag? If atoms are so small, how do we know what’s inside? How can indirect evidence be used to build a model? DO NOT OPEN your bag!! CHALLENGE: Make as many observations about the contents of your bag as possible without looking inside. 3-2-1 Summary 3 – List and describe the 3 atomic particles. 2 – Identify 2 questions you have about atoms. 1 – Share the fact that most surprised you about the size or structure of atoms.