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DO NOW

DO NOW. Object A at 40ºC and Object B at 80ºC are placed in contact with each other. Which statement describes the heat flow between the objects? Heat flows from object A to object B. Heat flows from object B to object A. Heat flows in both directions between the objects.

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DO NOW

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  1. DO NOW • Object A at 40ºC and Object B at 80ºC are placed in contact with each other. Which statement describes the heat flow between the objects? • Heat flows from object A to object B. • Heat flows from object B to object A. • Heat flows in both directions between the objects. • No heat flow occurs between the objects.

  2. Introduction to Atomic Theory Williamsburg High School for Architecture and Design Mr. Quinn and Ms. Tom 9/17/13

  3. AIM: What are atoms made of? What Do We Already Know?

  4. AIM: What are atoms made of? Origins of Atomic Theory • Atomic theory was developed by John Dalton in the mid 1800s • He used a combination of laws from chemical reactions

  5. AIM: What are atoms made of? Origins of Atomic Theory • J. J. Thompson developed the first model of the atom • Developed from cathode ray tubes • “Plum pudding model:” a positive cloud with negative particles in it

  6. AIM: What are atoms made of? Origins of Atomic Theory • Rutherford came up with the next model of the atom • Gold foil experiment • Atoms are mostly empty space

  7. AIM: What are atoms made of? Origins of Atomic Theory

  8. AIM: What are atoms made of? Parts of the Atom

  9. AIM: What are atoms made of? WAIT! Are you ready?

  10. AIM: What are atoms made of? Exploring Atomic Theory • Atoms start with a charge of zero. What does that mean for the number of protons and electrons in an atom? • They are the same! • Each element is identified by a unique atomic number. The atomic number is equal to the number of protons. What is the relationship between the atomic number and the number of electrons? • They are the same!

  11. AIM: What are atoms made of? Exploring Atomic Theory • Do positive and negative charges attract or repel each other? • Electrons orbit the nucleus like the earth orbits the sun. Why doesn’t the earth fall into the sun? • Electrons don’t fall into the nucleus for the same reason • They are orbiting too quickly

  12. AIM: What are atoms made of? Exploring Atomic Theory • The other number in each box on the periodic table is the atomic mass. For the small elements, what do you notice about its relationship to the atomic number? • It is about double • If the atomic number is set and electrons don’t have a mass, what makes up the balance? • Neutrons • What is the relationship between the number of protons and neutrons for most elements? • They are about equal

  13. AIM: What are atoms made of? Exploring Atomic Theory • Do similar charges attract or repel each other? • Repel • So would a bunch of protons in the nucleus attract or repel each other? • Repel • It is neutrons that hold them together.

  14. AIM: What are atoms made of? WAIT! Are you ready?

  15. AIM: What are atoms made of? Problem #1 • The mass of a proton is approximately equal to the mass of • an alpha particle • an electron • a neutron • a positron

  16. AIM: What are atoms made of? Problem #2 • What is the mass number of a carbon atom that contains six protons, eight neutrons, and six electrons? • 6 • 8 • 14 • 20

  17. AIM: What are atoms made of? Problem #3 • Which two particles make up most of the mass of a hydrogen-2 atom? • electron and neutron • electron and proton • proton and neutron • proton and positron

  18. AIM: What are atoms made of? Problem #4 • Which statement about one atom of an element identifies the element? • The atom has 1 proton. • The atom has 2 neutrons. • The sum of the number of protons and neutrons in the atom is 3. • The difference between the number of neutrons and protons in the atom is 1.

  19. AIM: What are atoms made of? Problem #5 • What is the charge of the nucleus of an oxygen atom? • 0 • –2 • +8 • +16

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