Matter & The Atom

1. Matter & The Atom

2. Matter Anything that takes up space and has mass Can be classified as solid, liquid, gas or plasma

3. Is it matter?

4. What is not matter? • ENERGY, HEAT, LIGHT, ELECTROMAGNETIC WAVES, MAGNETIC FIELDS, IDEAS, ETC. Properties of Matter • Describe the characteristics and behavior of matter, including the changes that matter undergoes

5. Observing Matter • Macroscopic Observations: Observations made with the 5 senses • Microscopic Observations: Observations made with a microscope • Submicroscopic Observations: Observations of substances so small they cannot even be seen with a microscope Macroscopic Microscopic Submicroscopic

6. Quantitative Observation: An observation that involves a numerical value. • Qualitative Observation: Describes the properties of a substance

7. Physical Properties quantitative What are the physical properties represented in the image above? characteristics qualitative

8. Chemical Properties

9. MIXTURES Two or more elements physically combined. How can you tell something is a mixture? It can be physically separated into its parts.

10. Heterogeneous Mixtures • The prefix “hetero” means “different” • A mixture with different compositions throughout • You can see each phase (part) of the mixture

11. Homogeneous Mixtures • The prefix “homo-” means “the same” • A mixture that is the same throughout • You cannot see the phases (parts) of the mixture.

12. HETEROGENEOUS OR HOMOGENEOUS?

13. Solutions • Solute: The substance being dissolved in a solution • Solvent: The substance that dissolves the solute • Aqueous Solution: A solution in which water is the solvent

14. What is the solute?What is the solvent? 82% Fe 18% Cr

15. ALLOY

16. Methods to Separate Mixtures • Filtration: Separates a solid from a liquid

17. Separating… • Magnet: Separates Fe, Co, or Ni

18. Separating… • Distillation: Separates two or more liquids with different boiling points.

19. Separating… • Crystallization: Separates crystalline solids from a saturated liquid

20. Separating… • Chromatography: Separates different types of liquids

21. PURE SUBSTANCE • Matter with the same fixed composition and properties • First Type of Pure Substance • Element • The Periodic Table: A chart that lists the chemical name and chemical symbol for each element • Chemical Symbol: A shorthand abbreviation for the name of an element • You can tell a substance is an element because it is on the periodic table -Can you separate an element? No Aluminum = ___ Gold = ____ Tin = ____

22. PURE SUBSTANCE • Matter with the same fixed composition and properties • Second Type of Pure Substance • Compound • Chemical Formula: A combination of chemical symbols that show what elements make up a compound and the number of atoms of each element • Subscript: A number written to the lower right of an element symbol to indicate the number of atoms of that • How do you know if a substance is a compound? If it is 1 thing only—and it is not on the periodic table. • Can you separate a compound? Yes—by chemically decomposing it. NaH2CO3 Mg(OH)2

23. Decomposing a Compound Electrolysis • “To tear apart with electricity” • The process in which electrical energy causes a non-spontaneous chemical reaction to occur • May break a compound apart into its elements • Electrolysis of PbBr2 & ZnCl2 • Electrolysis of Water

24. THE GREEK PHILOSOPHERS • 250 B.C. • Four Fundamental Elements: Earth, Wind, Water, and Fire made up everything in the world

25. DEMOCRITUS • 450 B.C. • Seashell experiment led to development of the idea of an indivisible piece of matter called “atomos” • Atom: The building block of matter • Problem: No experimental data to back his concept • Aristotle: Discredited Democritus

26. DEMOCRITUS’ ATOM

27. Law of Conservation of Mass • Antoine Lavoisier--1782 (Mercury & Oxygen Experiment) • Mass cannot be created nor destroyed in a chemical reaction • The mass of the reactants must equal the mass of the products in a chemical reaction

28. Law of Definite Proportions • Joseph Louis Proust-1799 • In a pure compound, the elements combine in definite proportions to one another according to mass • Water is always 2 Hydrogen : 1 Oxygen

29. Law of Definite Proportions Malachite

30. John Dalton-1803 • Elements are made of tiny particles called atoms • All atoms of a given element are identical • Atoms of a given element are different then every other element • Atoms of one element can combine with atoms of another element to form compounds • Atoms are indivisible and indestructible. Atoms can only be rearranged in chemical reactions--not created, divided, nor destroyed.

31. DALTON’S ATOM

32. Benjamin Franklin-1700’s • Kite experiment: • Objects have 1 of 2 electric charges • Called them + & - • Like charges repel • Opposite charges attract

33. Michael Faraday--1839 • Suggested that atoms contain particles that have electrical charge • Electricity (elektron, Greek word for amber) • The flow of electrons in a substance • Static: Stationary • Static Electricity: Electrical charges not in motion (socks out of a dryer)

34. J.J. THOMSON--1897 CATHODE RAY TUBE: Evacuated glass tube in which a stream of electrons emitted by a cathode strikes a fluorescent material, causing it to glow CATHODE: The electrode that brings electrons to the ions or atoms in a solution.

35. TELEVISIONS ARE CATHODE RAY TUBES

36. THOMSON’S PLUM-PUDDING MODEL OF THE ATOM Thomson measured the degree to which a magnetic field and an electric field deflected the cathode ray. Since the field was attracted to the positive charge, he knew it must contain a negative charge. By doing this he discovered the electron. Electron’s (negatively charged particles) are embedded in a ball of positive charge.

37. Henri Becquerel--1896 • Accidentally placed uranium on unexposed photographic film • Found an image had been produced on the film • Discovered that uranium exhibits radioactivity

38. Radioactivity • Radioactivity is the spontaneous emission of radiation from an element • Marie & Pierre Curie were awarded the Noble Peace Prize, along with Becquerel, for the discovery of radioactivity • The Curies isolated two other radioactive elements—radium and polonium • Elements with atomic numbers greater than 83 are radioactive

39. Robert Millikan—1909Oil Drop Experiment Using this experiment, Millikan determined the charge of the electron

40. Ernest Rutherford Alpha particle (α)—a particle with a +2 charge Beta particles ()—high-speed electrons Gamma radiation ()—not composed of particles

41. RUTHERFORD’S GOLD FOIL EXPERIMENT--1911 If Thomson’s model was correct, positive α particles would all go straight through the atom. However, Rutherford’s Gold Foil Experiment proved this to be untrue. Instead, every once in a while the α particle was repelled. Since α particles are positive, that meant there was a small, positive part of the atom.

42. RUTHERFORD’S NUCLEAR MODEL OF THE ATOM -- Center of the atom -- subatomic particle with no charge located in the nucleus -- subatomic particle with a positive charge located in the nucleus Concept: The atom is made of mostly empty space, containing electrons, surrounding a small, dense, positively charged nucleus.

43. James Chadwick—1930’s

44. Scanning Tunneling Microscope (STM)

45. STM IMAGES Nickel Platinum Iron on Copper

46. WHO RECEIVED THE NOBEL PRIZE FOR STM IN 1986? • Gerd Binnig and Heinrich Rohrer of the IBM Research Laboratory • 1981-Invented the STM which formed images of individual atoms

47. ATOM MANIPULATION Xenon on Nickel Iron on Copper CarbonMonoxide Man (on Platinum)

48. Particle Accelerator--FermiLab

49. What’s smaller than a proton? Atoms are composed of protons, electrons & neutrons which explain the behavior of matter. Other particles: quarks, gluons, mesons, muons & other exotic particles—no immediate chemical impact

50. ATOMIC SIZE • A typical atom is 0.000000001 meter across or 1 billionth of a meter • A quark is 0.000000000000000001 meter