Unit 1 Test de Chem Word Scramble
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Question | Answer |
Compare the theories of Democritus and Aristotle, and explain the derivation of the word “atomos.” | Aristotle believed in the four elements (dry, wet, warm and cold) and that changing the balance changed compositon; Democritus believed that matter is made up of tiny indivisible particles. Called them "atomos"= indivisible. |
Explain the theories of matter developed by Boyle and Lavoisier. | Boyle: stated a substance is NOT an element if it has 2 or more components. Lavoisier: "an element has one component and a compound has more than one element." Later: found the LAW OF CONSERVATION OF MASS |
State, explain, and give an example that illustrates the Law of Conservation of Mass, as well as use it in math problems. | Mass cannot be created or destroyed; total mass is unchanged in a closed system. If you put 2mL H20 in with 3mL Iodine, your result is guaranteed to have 5mL. |
Describe the properties of the gases isolated by Priestly and Cavendish, and explain the derivation of the names assigned. | Priesty: Isolated oxygen: made fire burn brighter and coal hotter; when put through water, made an acid. Oxy=acid, gen=common ending Lavendish: Isolated a gas (HYDROGEN) that if ignited in air formed water and heat. Hydro=water, gen=common ending |
State, explain, and give an example that illustrates the Law of Definite Composition, as well as use it in math problems. | All samples of a compound contain the same elements in the same ratio. In water, 8:1 Oxygen:Hydrogen. We add 6gO to 1.75gH: 8/1=6/h, 6=8h, h=3/4 (.75) so we have 1g H left over and 6.75g H20. |
Summarize Dalton’s Atomic Theory of Matter. Explain the discoveries that led to our current understanding that two of his points were incorrect, and state the ‘rewritten’ version of those points. | 1) Everything's made of small particles called atoms. 2! Atoms can't be subdivided, created or destroyed. 3! All atoms of an element are identical in SMP. 4) Atoms react with each other in whole # ratios. 5) Different element atoms have different ratios. |
State, explain, and give an example which illustrates the Law of Multiple Proportions, as well as use it in math problems. | Based on the 4th point, if 2 or more elements react to form more than 1 compound, the masses will react in small whole number ratios. 16gO+2gH=H2O 32gO+2gH=H2O2 (Ox2) |
Explain the derivation of the word “electron”, and the discovery that gave rise to it. | Comes from "elektron," meaning amber in Greek; saw how it, rubbed with wool, attracted dust and other things (static electricity) |
Explain Franklin’s contributions to the study of electrons. | Named charged objects positive and negative (signified opposites) Showed lighting is just big static electricity and that electricity could travel thru air, not just solids. |
Explain the experiments, results, and meaning of each of the five cathode ray tube experiments. (Crookes) | See paper. |
Explain the experiment and logic that led to Milikan’s derivation of the charge and mass on a single electron. | Sprayed oil droplets and allowed to fall thru chamber, some negatively charged from X rays dislodging xtra electrons. Adjusted metal plate voltage until charged oil drops hovered; then found all negative charges= whole # multiples of same #. Mass=Thom. |
Diagram and explain Thomson’s model of the atom. | (Ball with lots of little negative charges in positive fluid) Called the Plum Pudding model: thought lots of electrons were in a positive liquid/gas |
Explain the experiment, results, and meaning of the gold foil experiment. | Rutherford had Geiger and Marston direct alpha particles (+ charge) through a lead plate to a sheet of almost 1 atom thick gold foil. Most particles went thru but 1/8000 bounced back, proving the positive charge wasn't a fluid. |
Diagram and explain Rutherford’s model of the atom. | Called "Planetary Model": Ball with electrons around outside, and one big positive nucleus in the center. That way, all positive charge is focused in 1 place. (Later found this to be "proton.") |
Identify the three subatomic particles, their charges, locations, and relative masses. | Proton: positive, in nucleus and large (practically .5 of H atom), Neutron: neutral, in nucleus and large, Electron: negative, far outside nucleus and puny (1/2000 of hydrogen atom) |
Explain mass defect and what holds the nucleus together. | E=mc^2: E=nuclear binding energy, m=mass defect and c^2 is just a #. Nuclear binding energy holds atom together; missing mass is simply present in energy. |
Identify elements, compounds, homogeneous mixtures and heterogeneous mixtures. | Elements- 1 kind of atom Compounds- more than one element bound together Homogenous mixture- non-chemically-bound chemicals appearing same Heterogeneous mixtures: Same above, but don't look same... |
Identify chemical and physical changes. | Physical: Phase or appearance change Chemical: Changes identity of substance |
Identify and give examples of the four indicators of a chemical reaction. | Light (fire gives off light) Color (adding those 2 in class turned pink) Evolution of gas (adding acids and bases together causes toxic gases to come off top of mixture) Evolution of a precipitate: adding the 2 in class that made slush... |
Explain the different methods of separation and what property is used for each. Identify which method is best for a given mixture. | Particle size: Sifting/Filtration Density: Centrifuging Solubility: Crystallization Polarity: Chromatography Boiling Points: fractional Distillation (f. Crystallization) |
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