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Metric Abbreviations: Mega, Kilo, Hecto, Deka, Deci, Centi, Milli, Nano
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Mega=M; Kilo=k; Hecto=h; Deka =da; Deci =d; Centi =c; Milli=m; Nano=n
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Conversion Factor
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A fraction which expresses an equality between two units of measurement and can be used to convert from one to the other (ex. 1kg/1000g)
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Use conversion factors to solve: 1) How many kilograms in 2000 g? 2) How many feet in 60"?
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1) (2000g)(1kg/1000g) = 2kg; 2) (60")(1'/12") = 5 ft
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Significant digits
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Digits which are measured. All non-zero digits are significant. Zeros are significant unless they are placeholders
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Scientific notation
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A number expressed as Ax10B. "A" is between 1.00 and 9.99 and "B" is an integer.
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Write conversion forumlas: 1) Celsius to Fahrenheit; 2) Celsius to Kelvin
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1) ˚f = (1.8 x ˚celsius) + 32; 2) Kelvin = ˚celsius +273
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Energy
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The ability to do work; it is released or absorbed during chemical reactions in the form of heat, light, electricity. (calorie, Joule: 1cal = 4.18J)
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Matter
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A substance that occupies space has mass.
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Compare Weight vs. Mass
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Mass is the amount of matter. Weight measures gravitational force. Mass never varies. Weight can vary.
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Compare potential energy and kinetic energy
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Potential energy is energy due to position. KE is energy of motion.
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Explain how to convert a number greater than 1 to scientific notation
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Move decimal point to left until only 1 digit remains to left. Indicate number of moves as a positive exponent of 10. 3301 = 3.301x10^3
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Explain how to convert a number less than 1 to scientific notation
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Move decimal point to right until only 1 digit remains to left. Indicate number of moves as a negative exponent of 10. (0.00356 = 3.56 x 10-3
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Explain the rules for multiplying the numbers in scientific notation
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Multiply the first numbers and add the exponents. (3x10^5)(2x10^3)= 6x10^8
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Explain the rules for dividing the numbers in scientific notation
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Divide the first numbers and subtract the exponents. (8x10^6)/(2x10^10) = 4x10^-4
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Physical properties
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Properties which can be observed without changing the substance into something different. Color, odor, hardness, density, luster, state, conductivity, solubility, boiling and melting points
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Chemical properties
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A chemical property is observed when a substance changes into a new substance. Iron forms rust in air & water; gasoline burns in oxygen
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Physical change
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Substance changes form or state only. Boiling, melting, freezing, dissolving, grinding, cutting
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Chemical change
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Where new substances are formed with new chemical and physical properties. Oxygen & hydrogen form water; sodium & chlorine form sale (sodium chloride)
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Density: Write the general equation and three standard units
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The mass of a unit volume of a substance. Density = mass/volume = g/mL; g/L; kg/L
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Element. List some examples
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A substance is composed of identical atoms. Gold, silver, oxygen, hydrogen, lead, chlorine, helium, iron, copper, fluorine, arsenic
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Compound. List some examples
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substance composed of two or more elements chemically combined. Water - H2O; Salt - NaCl; Sugar - C6H12O6; Ammonia - NH3
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Mixture. List some examples.
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A combination of substances held together by physical means (dirt, milk, soup, saltwater, granite)
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Homogeneous and Heterogeneous mixtures. Provide examples.
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Homogeneous mixtures are uniform in composition (air, metal alloy, salt water). Heterogeneous mixtures are not uniform in composition (dirt, spaghetti sauce)
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Three postulates of Dalton's Atomic Theory
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1) An element is composed of identical atoms; 2) Atoms of different elements have different properties; 3) Compounds are atoms of 2 or more elements chemically combined
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The Law of Conservation of Mass
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During a chemical reaction, matter is neither created nor destroyed
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The Law of Constant Composition
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A compound always contains the same elements combined in the same proportions by mass (H2O) is 88% oxygen no matter where it is found)
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Law of Multiple Proportions
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The same elements may combine to form more than one compound. The ratios of atoms are in small whole numbers (H2O and H2O2)
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Atomic Mass Unit
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the mass of a proton or neutron is equal to 1 atomic mass unit. Symbol - "amu"; 1 amu=1.66x10^-24
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Atomic Number: What are the atomic numbers of helium, hydrogen, carbon, oxygen?
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The number of protons in the nucleus of an atom of an element. Helium-2; carbon-6; hydrogen-1; oxygen-8
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Mass number
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The sum of protons plus neutrons n the nucleus of an atom
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Isotope
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Atoms which contain the same numbers of protons but different numbers of neutrons (ex. Hydrogen has 3 isotopes with mass numbers of 1,2,3)
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Molecule
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A group of two or more atoms held together by chemical bonds
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Ion (provide examples)
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An atom or group of atoms which contains a positive or negative electrical charge (ex. Na+; Cl-; SO4^2-)
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Cation and Anion (provide examples)
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cation - positively charged ion (Na+; Fe+2; NH4+; Ag+); anion - negatively charged ion (Cl-; SO4-2; OH-; P-3)
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Valence electroncs
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The electrons found in the outermost energy level of an atom
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Oxidation number
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A number (positive or negative) representing the charge on an ion or atom involved in a chemical bond
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Three general rules for determining oxidation numbers
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1) Atoms of uncombined elements equal 0; 2) Hydrogen = +1 (in metallic hydrides =-1); 3) Oxygen = -2 (in peroxides =-1); (bonded with fluorine =+2)
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Empirical Formula. What are the molecular and empirical formulas of peroxide?
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An expression which gives the relative numbers of atoms of the elements in a molecule. Expressed as the lowest possible set of integers (H2O2, HO)
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Molecular Formula. What is the molecular formula for ammonia?
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An expression stating the number and kind of each atom present in a molecule of a substance (NH3 has 1 nitrogen atome and 3 hydrogen atoms in each molecule)
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Positive Ion: which elements tend to form them?
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Metals tend to form positive ions by losing electrons (Na → Na+ e-)
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Negative Ion: which elements tend to form them?
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Non-metals form negative ions by gaining electrons (Cl +e- →Cl-)
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Write oxidation numbers for ions of: Group IA & IIA; Group VIA & VIIA
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IA→+1; IIA→+2; VIA→-2; VIIA→-1
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Write formula for compounds of: 1) Sodium & Sulfate; 2) Magnesium & Nitrite; 3) Aluminum & Phosphate
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1) Na2SO4; 2) Mg(NO2)2; 3) AlPO4
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Names of the ionic compounds: 1) FeCL3; 2) FeO; 3) Cu(OH); 3) Cu3PO4
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1) iron (III) chloride; 2) iron (II) oxide; 3) copper (II) hydroxide; 4) copper (I) phosphate
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10 prefixes used to name covalent compounds
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Mono=1; Di=2; Tri=3; Tetra=4; Penta=5; Hexa=6; Hepta=7; Octa=8; Nona=9; Deca=10
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Forumlas and names of acids formed from: 1) F; 2) Cl; 3) Br; 4) I
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1) HF - hydrofluoric acid; 2) HCl - hydrochloric acid; 3) HBr - hydrobromic acid; 4) HI - hydriodic acid
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Names of acids: 1)H2SO4; 2) HNO2; 3) H3PO4; 4)HClO
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1) sulfuric acid; 2) nitrous acid; 3) phosphoric acid; 4) hypochlorous acid
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Write the equation for Percent Composition. What is the percent composition of Ca in CA(OH)2?
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%=(me/FW)(100%); %= percent composition of the element; me=mass of element in one formula unit; FW = formula weight; (40/74)(100%) = 54% Ca in Ca(OH)2
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Atomic Mass
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A weighted average mass of the atoms of an element (assuming the carbon-12 isotope is exactly 12) (ex. Atomic mass of C=35.45 is calculated from two isotopes. Cl-35 and Cl-36)
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Write the equation to calculate the atomic mass of an element
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Atomic mass of X = ((mx1)(%x1)/100%) + ((mx1)(%x1)/100%)) + etc.; mx1, mx2, mxN = atomic masses of each isotope of element; %x1, %x2, %xN = percent composition of each isotope
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