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Chemistry Finals Chemistry—study of the composition, structure, and properties of matter and the changes it undergoes Element—pure substance made of only one kind of atom Compound—substance that is made from the atoms of two or more elements that are chemically bonded Chemical Change or Reaction—one or more substances are converted into different substances Physical Property—characteristic that can be observed or measured without changing the identity of the substance Chemical Property—substance’s ability to undergo changes that transform it into different substances Intensive Property—does not depend on the amount of matter present Extensive Property—depend on amount of matter present Physical Color Melting Point Boiling Point Chemical Reacts With… Intensive Electricity Conductor Melting/Boiling Pt. Density Extensive Volume Mass Conversion Factor—ratio derived from the equality between two different units that can be used to convert from one unit to the other Scientific Method—logical approach to solving problems by observing and collecting data, formulating hypotheses, testing hypotheses, and formulating theories that are supported by data Hypothesis—testable statement, often stated as “if-then” Significant Figures—consist of all digits known with certainty plus one final digit, which is somewhat uncertain or estimated Volume—amount of space occupied by an object Theory—broad generalization that explains a body of facts or phenomena Model—(in science) more than a physical object; it is often an explanation of how phenomena occur and how data or events are related Mass—measure of quantity of matter (measured in Kilograms (Kg)) Scientific Notation—numbers are written in the form M * 10N, where the factor M is a number greater than or equal to 1 but less than 10 and N is a whole number Weight—measure of gravitational pull on matter (measured in Newtons (N)) TABLE 2-5 Rules for Determining Significant Figures Rule Examples 1. Zeroes appearing between nonzero digits a. 40.7 L has three significant figures are significant b. 87 009 km has five sig figs 2. Zeros appearing in front of nonzero a. 0.095 897 m has five significant figures digits are not significant b. 0.0009 kg has one sig fig 3. Zeros at the end of a number and to the a. 85.00 g has four sig figs www.geocities.com/yoshi120.geo/science right of a decimal are significant 4. Zeros at the end of a number but to the left of a decimal may or may not be significant. If such a zero has been measured or is the first estimated digit, it is significant. On the other hand, if the zero has not been measured or estimated but is just a placeholder, it is not significant. A decimal placed after the zeros indicates that they are significant. b. 9.000 000 000 mm has 10 sig figs a. 2000 m may contain from one to four sig figs, depending on how many zeros are placeholders b. 2000. m contains four sig figs, indicated by the presence of the decimal point EXAMPLE TABLE Scientific Notation 6.022 * 1023 2.56 * 103 3.14 * 101 (Avagadro’s #) 7.77 * 1077 1.0 * 10100 (One Googol) Cathode Ray Tube—glass tube (See pg. 70). Experiment using a cathode ray tube, in 1897, by English physicist Joseph John Thomson, concluded that all cathode rays (known now as electrons) are composed of identical negatively charged particles Mole—scientific counting number (like a dozen) that uses Avogadro’s Number. Looking at the periodic table, elements have their atomic weights listed below them in Atomic Mass Units (AMU). One mole of that element takes that number from AMUs into grams. I.e., one mole of carbon-12 (carbon atoms that all have a mass of 12 AMU) would have a mass of 12 grams Avogadro’s Number—6.022 * 1023 Atom—smallest particle of an element that retains the chemical properties of that element John Dalton—(1808) English schoolteacher who proposed an explanation for the law of conservation of mass, the law of definite proportions, and the law of multiple proportions. Here are his rules: 1. 2. 3. 4. 5. All matter is composed of extremely small particles called atoms. Atoms of a given element are identical in size, mass, and other properties; atoms of different elements differ in size, mass, and other properties. Atoms cannot be subdivided, created, or destroyed. Atoms of different elements combine in simple whole-number ratios to form chemical compounds. In chemical reactions, atoms are combined, separated, or rearranged. John Dalton—(cont.) turned Democritus’ idea into a scientific theory that could be tested by experiment. Not all parts of Dalton’s Atomic Theory have proven correct—one example is that atoms can be broken into quarks Bohr’s Model—shows how an electron from a hydrogen atom absorbs energy, goes up one energy level, emits the energy, and returns to the previous (ground) level. See more on pg. 96 Nuclide—general term for any isotope of any element www.geocities.com/yoshi120.geo/science Isotopes—atoms of the same element that have different masses Parts of the Atom—nucleus containing protons and neutrons and electron cloud containing (GUESS!) electrons TABLE 3-1 Properties of Subatomic Particles Particle Symbol Relative Charge Electron e-1 + Proton p +1 Neutron n0 0 Mass Number 0 1 1 Molar Mass—mass of one mole of a pure substance Mass Number—total number of protons and neutrons in the nucleus of an isotope Nuclear Forces—short-range proton-neutron, proton-proton, and neutron-neutron forces that hold nuclear particles together Law of Conservation of Mass—mass is neither created nor destroyed during ordinary chemical or physical reactions Robert A. Millikan—continued from Thomson’s cathode ray tube experiment. Millikan discovered that the mass of the electron is in fact about one two-thousandth the mass of the simplest type of hydrogen atom and that electrons carry a negative charge. Thus, (1) because atoms are electrically neutral, they must contain a positive charge to balance the negative electrons, and (2) because electrons have so much less mass than atoms, atoms must contain other particles that account for most of their mass The electrons of the outer shell (valence) are separated from the kernel (non-valence) electrons by AN ENERGY LEVEL. (Does it make sense now?) Electromagnetic Radiation—form of energy that exhibits wavelike behavior as it travels through space. Also travels through matter as a particle (p. 93—Einstein’s dual wave-particle theory) Wave Speed— c = v. C is the speed of light (or any electromagnetic radiation), 3.0 * 108. (lambda) is the wavelength—distance between corresponding points on adjacent waves (pg. 91). V is the frequency—the number of waves that pass a given point in a specific time, usually one second, expressed in waves per second (a hertz (Hz)) The most stable state of an atom can be one of two things—either the most stable isotope of an element, which would happen to be the most common isotope, or (back to Bohr’s Model) when the electrons of an atom are at ground level (by not absorbing additional photon energy) Electron Cloud—space surrounding nucleus, containing the electrons of an atom Orbital—3-d region around the nucleus that indicates the probable location of an electron www.geocities.com/yoshi120.geo/science Quantum—minimum quantity of energy that can be lost or gained by an atom, formulated as E = h v. E is the energy, in joules, of a quantum of radiation; v is the frequency of the radiation emitted; h is Planck’s constant, 6.626 * 10-34 J s (joules per second) Orbital Notation—uses arrows to represent electrons in an atom Electron Configuration Notation—uses superscripts, like 1s1 for hydrogen, to represent electrons. If you don’t know what these notations are, you shouldn’t have slept in class (or at least not as much) Group Names—groups are vertical (Families are horizontal) Alkali Metals—all of group 1 except hydrogen Alkaline-Earth Metals—group 2 Halogens—group 17 Noble Gases—group 18 S-Block—groups 1 and 2 P-Block—groups 13-18 D-Block—groups 3-12 (transitional elements) F-Block—lanthanides and actinides Ion—atom or group of bonded atoms that has a positive or negative charge Periodic Table Arrangement—everything on the table reoccurs periodically; elements with similar properties fall in the same column or group (pg. 123-125) Atomic Radii of Ions—anions, missing electrons, have a larger atomic radius due to less atomic charges pulling the atom together. Cations, if you haven’t guessed, have a smaller atomic radius due to increased atomic charges pulling the atom together Atomic Radii of Neutral Elements of the Table—going down a group, atoms have a larger atomic radius due to more electron levels. Going across a family, atoms (usually) have a smaller atomic radius due to more electrons within the same electron levels and sublevels. The rare exception occurs within new sublevels created in an already used level, such as a new electron in the P sublevel after its last F and D sublevels were filled Electronegativity—measure of the ability of an atom in a chemical compound to attract electrons. Elements are rated on a scale of 0 to 4, with the perfect 4 going to Fluorine. Electronegativity determines the type of bond that occurs between elements—the difference between two elements causes the following bonds: Ionic—greater than 1.7 Polar Covalent—from 0.3 to 1.7 Non-Polar Covalent—less than 0.3 Electronegativity Table—pg. 151 Ionic Bonding—chemical bonding that results from the electrical attraction between large numbers of cations and anions Covalent Bonding—results from the sharing of electron pairs between two atoms Non-Polar Covalent Bond—covalent bond in which the bonding electrons are shared equally by the bonded atoms, resulting in a balanced distribution of electrical charge www.geocities.com/yoshi120.geo/science Polar-Covalent Bond—covalent bond in which the bonded atoms have an unequal attraction for the shared electrons Ionic Compound—composed of positive and negative ions that are combined so that the numbers of positive and negative charges are equal Molecular Compound—chemical compound whose simplest units are molecules—a neutral group of atoms that are held together by covalent bonds Formula Unit—simplest collection of atoms from which an ionic compound’s formula can be established Chemical Formula—indicates the relative numbers of atoms of each kind in a chemical compound by using atomic symbols and numerical subscripts Molecular Formula—shows the types and numbers of atoms combined in a single molecule of a molecular compound. The chemical formula of a molecular compound is referred to as this Common Compounds will be on the final! Table 7-2 will be provided How many moles are in C6H12O6?—easy as pie or any other sugar-object—6 mol carbon, 12 mol hydrogen, and 6 mol oxygen Balance this—___HNO3 + ___Mg(OH)2 ___Mg(NO3)2 + ___H2O Answer—2HNO3 + Mg(OH)2 Mg(NO3)2 + 2H2O More on pg. 252 MoleGram Conversion—multiply an element’s number of moles by its atomic mass GramMole Conversion—divide an element’s number of moles by its atomic mass Formula Weight—the mass, in AMU, of a formula. Multiply each element’s mass in the formula by the number of atoms each element has, then take the sum Molar Mass—the mass, in grams, of one mole of a formula Percent Composition—for each element, divide its mass over the mass of the entire formula. Multiply by 100 and label with “% (element)” Empirical Formula—the symbols for the elements combined in a compound with subscripts showing the smallest whole-number mole ration of the different atoms in the compound Gift of Density—considered a gift due to how easy it is—density = mass / volume Metric Meter Know-How 1000 meters make up one kilometer 100 centimeters make up one meter 1000 millimeters make up one meter 10 millimeters make up one centimeter How many millimeters are in a kilometer? 1 km x 1000 m 1 km x 100 mm 1m = 10,000 mm www.geocities.com/yoshi120.geo/science