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Bell Work: Tuesday 2/7/12

Bell Work: Tuesday 2/7/12. On the front table there is a stack of papers titled “Mercury: Mysterious and Deadly”. Get one of these papers It is an article that you will read silently There are 7 questions you will answer by yourself on the back.

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Bell Work: Tuesday 2/7/12

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  1. Bell Work: Tuesday 2/7/12 • On the front table there is a stack of papers titled “Mercury: Mysterious and Deadly”. • Get one of these papers • It is an article that you will read silently • There are 7 questions you will answer by yourself on the back. • On your Bell Work for “Tuesday” you need to write “ARTICLE”

  2. Mercury: Mysterious and Deadly Questions • How did Mercury get the nickname “quicksilver”? • What did alchemists struggle to make using mercury and sulfur? • Many people over time were found to have health problems. What was eventually found to be the cause of it? • What type of effects happen to people surrounded by mercury? • High School Chemistry Story • Why is vacuuming a mercury spill not the best way to clean up a mercury spill? • Middle School Story • What does this article have to do with Chemistry? • Why would your teacher have you read an article like this?

  3. …describe how the elements are arranged on the Periodic Table of Elements …describe the atom as the basic building block of matter …identify substances based on their physical and chemical properties …sort elements based on their physical & chemical properties By the end of this unit, you will be able to… …identify the bonds that hold atoms together and describe properties associated with these bonds …separate mixtures into their basic components

  4. Setting Goals Questions to Consider: • What do you hope to accomplish throughout the upcoming Chemistry unit? • What goals do you have for the rest of the 2nd semester? • What long-term goals do you have for science?

  5. What is an Atom?- page 1 • 5.1 - TSW explain that matter is composed of tiny particles called atoms. • Atom- basic building block of all matter • All substances are made up of matter • Smallest particle of an element that has the properties of that element

  6. Structure of an Atom • Nucleus- tiny, central core of an atom • Contains protons (positively-charged) • Containing neutrons (with no/neutral charge) • Electrons move around the nucleus in electron cloud

  7. BellWork: Wednesday 2/8/12 • Get a book off the front table and the pink packet. • Begin working on page 1 – the Nature of Science Vocab. • Be sure to have the definition of each word written down • You will only be given 10 minutes to work on this. • Whatever is not finished today will be done as homework.

  8. Subatomic Particles- particles that make up an atom • Proton- positively charged; located in nucleus • Neutron- neutrally charged; located in nucleus • Electron- negatively charged; located outside of the nucleus; negligible mass (very small) • Electrons revolve around nucleus in imaginary paths called orbits or shells • Valence electrons- electrons that are the farthest away from the nucleus (in the outside shell)

  9. The Role of Electrons Electrons… • …move around the nucleus very fast • …have a HUGE space to move around in • …are different distances from the nucleus • …form a negatively charged cloud around the nucleus • …travel in paths called orbitals • …cannot be exactly located at a particular moment- probably do (probability) • Imagine the blades of a moving fan…where are they exactly?

  10. D Fill in these on page 1 • Fill in the picture on page 1 with the appropriate subatomic particle names, charges, and locations in the atom. C A B

  11. Little Particles, Big Spaces • Imagine standing at the pitcher’s mound in a baseball stadium. • If the nucleus were the size of a pencil eraser, the electrons could be in the outfield or the top row of seats!

  12. Atomic number Ex: Every Carbon atom has 6 protons How many electrons in a Carbon atom? 6 (# of (+) protons = # of (-) electrons) • Atomic Number- the unique number of protons in a nucleus • # of (+) protons = # of (-) electrons • Atoms are neutrally charged (not positive or negative)

  13. Atomic Mass- the average mass of one atom of an element; protons + neutrons • Atomic mass units (amu)- unit for measuring very small mass of subatomic particles • Proton mass = 1 amu • Neutron mass = 1 amu • Electron mass = 1/2000 amu • ~2000 electrons = 1 amu • Most of an atom’s mass is in its nucleus

  14. Check Your Understanding • Gold, Au, has an atomic number of 79 • How many protons? • 79 • How many electrons? • 79 • Gold, Au, has an atomic mass of 196.97 • How many neutrons? • 196.97 – 79 = 117.97 • How many amu’s • 79 + 117.97 = 196.97 At your party you need 10 pizzas to feed everyone. You buy 6 pizzas. How many pizzas must other people provide if you are going to have 10 total? The total # of pizzas is like the atomic mass. Protons bring some of the mass, and neutrons bring the rest. Electrons don’t really bring anything!!!

  15. What is an Element? • Element- Substance made up of one kind of atom • Cannot be broken down into other substances by chemical and physical means • All listed in the Periodic Table • ~82 naturally-occurring elements • ~31 synthetically prepared (artificially-made) elements Germanium Sulfur Mercury

  16. “Element” = Carrot • Imagine chopping a carrot into smaller and smaller pieces. • You would eventually reach a point where you could not cut anymore because the pieces were so small. • But, those small pieces still have the properties of the larger carrot (taste, color, etc.). • Element = Aluminum • Imagine cutting Aluminum (Al) into smaller and smaller pieces. • When you can no longer divide it, they are Al atoms. • But, they still have the properties of Aluminum (shiny, silver color, fragile, thin, etc.)

  17. Molecules vs. Compounds When atoms bond together, they form: • Molecule – a combination of 2 or more of the same or different atoms that are bonded together • Ex:H2O, NaCl, H2, O2, O3, N2 • Diatomic Molecule- made of two of the same atoms • Hydrogen, Nitrogen, Fluorine, Oxygen, Iodine, Chlorine,Bromine • H2 O2 F2 Br2 I2 N2 Cl2 • HOFBrINCl twins; IHave No Bright Or Clever Friends; Hydrogen; the rest form a 7 on the periodic table: N, O, F across, then going down Cl, Br, I • Compound – a molecule that contains atoms or molecules of two or more different elements • Ex: H2O, C6H12O6, CH4

  18. Fill these in on page 1 D Bellwork: Thursday 2/9/2012 • Fill in the following chart with the appropriate subatomic particle names, charges, and locations in the atom. C A B

  19. What is a Theory and how do you make one? • Hypothesis – an educated guess, based on observation • Theory – summarizes a hypothesis or group of hypotheses that have been supported with repeated testing. This answers the question of “why” • This is valid as long as there is not evidence to dispute it. • Law – generalizes a body of observations. At the time it is made, no exceptions have been found. These explain things, but do not describe them. Does not answer “why” • For a theory to become a law it must… • Not have any evidence to disprove it • Have a hypothesis that has been testing many different ways and times

  20. Evolution of the Atomic Theorypgs 2 & 3 • Read the passages provided, and answer the questions about each scientist and their experiments.

  21. Evolution of the Atomic Theory- pg 3 John Dalton J.J. Thomson The electron Negative Negatively charged electrons Opposite charges attract each other Gas discharge tubes • Atomic Theory of Matter • Atoms • Different • Atoms of different elements • 1:1

  22. Evolution of the Atomic Theory- pg 4 Lord Ernest Rutherford Niels Bohr The electrons go around the nucleus like planets around the sun. They are in different energy levels; different distances from the nucleus 32 electrons Higher level = absorb/gain energy Release (lose) • Positive • He was shooting alpha particles through a gold foil sheet • Most particles passed straight through the foil. • Some got deflected back, others went through. • Positive repels positive (positive nucleus repels positive alpha particles)

  23. Evolution of the Atomic Model J.J. Thomson (1897) Ernest Rutherford(1911) John Dalton (1802) Erwin Schrödinger & Louis de Broglie (1920’s - present) Niels Bohr (1913)

  24. Democritus (~400 bc) • Who was he? • A Greek philosopher • Discovery: • Matter can be cut into small pieces • The smallest piece cannot be broken down anymore = an atom • “Atomos” – Greek for uncuttable • Everything is composed of atoms • Atoms are always in motion • Model: The atom is a small, solid sphere

  25. John Dalton(1802) • Who was he? • British schoolteacher, meteorologist • Experiment: • Studied the atmosphere and the behavior of gases; he found they always combined in predictable ways. • Discovery (1802): • Each element is made up of atoms • Atoms of the same element are the same. • Atoms of different elements are different • “Billiard Ball Model” (Pool Ball): • The atom is a small, solid sphere

  26. Bellwork: Friday 2/10/2012 • Nucleus • Protons & Neutrons • Nothingness! Empty space around the nucleus 99.9% of matter is actually empty space! • 4 protons, 5 neutrons, 4 electrons, • Where is the majority of an atom’s mass? • What subatomic particles compose the majority of an atom’s mass? • Tricky: What composes the majority of an atom’s volume? • Beryllium’s atomic number is 4, and its atomic mass is 9.01. How many protons, neutrons, and electrons are in one Beryllium atom?

  27. Evolution of the Atomic Model J.J. Thomson (1897) Ernest Rutherford(1911) John Dalton (1802) Erwin Schrödinger & Louis de Broglie (1920’s - present) Niels Bohr (1913)

  28. J.J. Thomson (1897) • Who was he? • A British scientist • Experiment: • Using a gas-discharge/cathode ray tube, he passed an electric current through a vacuum tube • Saw a stream of glowing material!! • Discovered that mysterious glowing stream would bend toward a positively charged electric plate • The stream was made up of small particles that carried a negative charge--electrons.

  29. Discovery (~1897): • The negatively charged electron • 2000 electrons = the mass of one proton • The “Plum-Pudding Model”: • Atoms are spheres filled with a positively charged fluid; electrons are scattered throughout • Fluid = “pudding”; electrons = “plums”

  30. Lord Ernest Rutherford(1909-1911) • Experiment:“TheGold-Foil Experiment” • Fired positively charged particles (called alpha particles) at a thin sheet of gold foil • Most particles went through, some bounced back, some were deflected • Who was he? • New Zealand physicist

  31. Discovery (1909-1911): • Atom is mostly empty space • Positively charged nucleus in the center of the atom • positive repels positive • The “Planetary Model”: • Dense, small, positively charged nucleus • Surrounded by freely moving electrons

  32. Niels Bohr(1913) • Who is he? • A Danish physicist • Experiment: • Known: • Elements possess specific amounts of energy • Light was given out when they were heated, but no one could explain why • Bohr looked at line spectra (colored lines of light), which show energy being emitted. • Energy was released when electrons moved from one shell to another • Bohr suggested the electrons must orbit nucleus in fixed energy levels (or electron shells)

  33. Discovery (1913): • Electrons move in fixed orbits around the nucleus (electron shells) • Electrons exist in energy levels • Atoms absorb or give off energy when electrons move from one shell (energy level) to another • The “Bohr Model”: • An electron's energy levels (also called electron shells) can be imagined as concentric circles around the nucleus

  34. Erwin Schrödinger & Louis de Broglie (1925 through Present) • Who were they? • Louis de Broglie was a French scientist • Erwin Schrodinger was a Austrian physicist • Experiment/Observation: • It is impossible to know the speed and exact location of an electron • It is only possible to calculate the probability of finding an electron within a given space

  35. Discovery (~1925): • Electrons travel in clouds around the nucleus • Electrons can behave like waves or particles • The “Electron Cloud Model” or “Quantum Mechanical Model”: • There are no defined orbits of electrons around the nucleus, just areas where they “might” orbit

  36. Atomic Theory Timeline- Recap

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