Chemistry 121 Week one of notes
Chemistry 121 Week one of notes CHEM 121
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This 5 page Class Notes was uploaded by Erin Swanson on Monday February 1, 2016. The Class Notes belongs to CHEM 121 at University of North Dakota taught by Shaina Mattingly in Winter 2016. Since its upload, it has received 35 views. For similar materials see General chemistry in Chemistry at University of North Dakota.
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Date Created: 02/01/16
Chemistry 121 Notes for Chapters 0-2: Chapter 0: Accuracy: How close a measured value is to the known actual value. Precision: How close measurements are to each other. Significant Figures: The total number of digits recorded for a measurement -The last digit is estimated Counting sigfigs: With no zeros: there are as many sigfigs as there are digits With zeros inbetween 2 non-zero digits: always counted Zeros at the beginning: Never counted Zeros at the end AND before a decimal: always counted Addition and subtraction with sigfigs: Round to the smallest number of digits after the decimal point Multiplication and division with sigfigs: Round to the smallest number of TOTAL sigfigs Chapter 1: Atomic symbol: the single/double letter for the elements Period: horizontal row Group: Vertical column Metals: -Lustrous (shiny) -ductile (drawn into wires) -Malleable (opposite of brittle) -Conduct electricity/heat -Melting point is high (generally) Nonmetals: -Brittle -Do not conduct electricity/heat -Variable melting points Semimetals: -Can be lustrous -Conducts electricity/heat to some extent -Brittle -Solids at room temperature Chemical Properties: Result in chemical changes -Rusting/oxidation -Combustion/burning -Tarnishing/Varnish/Hardening Physical Properties: Result in physical changes -Temperature -Color -Melting Point/Freezing Point Intensive Property: Independent of sample size -Melting Point -Color -Density Extensive Property: Dependent on sample size -Length -Volume -Mass Alkali Metals: -Group 1A elements -all solid metals except hydrogen -react violently with water -never in nature Alkaline earth metals: -Group 2A -Less reactive -never pure in nature Halogens: -Group 7A -F and Cl are gases -Exist as diatomic molecules Noble Gases: -Group 8A -Colorless gases that are inert (low reactivity) -He and Ne are completely inert Law of Conservation of Matter: matter is neither created nor destroyed in a chemical reaction Law of Definite Proportions: Different samples of a pure chemical compound always contains the same proportion of elements by mass Atomic number: How many protons Mass number: Sum of protons + Neutrons Neutral Atoms: equal numbers of Protons and neutrals Isotope notation: changing the neutron amount Atomic Masses: measured in atomic mass unites (amu) also called unified atomic also called unified atomic mass unit (u) Atomic weight: takes into account the many isotope abundancies and percentages Moles (Avogadro’s number): one mole of any element is the amount who’s mass in grams (molar mass) is numerically equal to the atoms atomic weight Chapter 2: Electromagnetic energy: energy in the form of electrical and magnetic waves that are reflected or emitted from an object Wavelength: smallest wavelength is gamma rays wavelength increases from left to right Frequency: largest frequency is gamma ray frequency decreases from left to right Amplitude: the height of the wave maximum from the center -Wavelength and frequency are inversely related -Wavelength and energy are inversely related -Energy and frequency are directly related Blue Light: higher frequency, shorter wavelength Red Light: Lower frequency, longer wavelength Photons: light particles Work function: the amount of energy required to eject an electron from a metal -higher work function, the easier to lose and electron First quantum number: the principle quantum number (n) -n is a positive integer n=1 or 2 or 3 or 4 or 5… -as n increases, the number of allowed subshells and orbitals increases Second quantum number: The angular momentum quantum number (l) -value of l depends on value of n, l has a RANGE of integer values, l= 0 to n-1 -Main values of l: -l=0 describes S orbital -l=1 describes P orbital -l=2 describes D orbital -l=3 describes F orbital Third Quantum number: the magnetic number m l -describes the orientation of the electron orbital -each value of l has its own range of integer values for m= -1lto +1 Fourth quantum number: electron spin and Pauli’s exclusion principle (m ) s -differentiates the two electrons in an orbital Pauli Exclusion Principle: No two electrons in an atom can have the same values of their four quantum numbers Aufbau Principle: 1. Lower-energy orbitals are filled before higher energy orbitals 2. An orbital can hold two electrons, each of which must be opposite spins 3. If two or more degenerate orbitals are available, one electron goes into each until half full Exceptions: 1 5 Chromium: [Ar] 4S 3D 1 10 Copper: [Ar] 4S 3D Electron Configuration: - S-subshell: 1 orbital, 2 electrons max - P-subshell: 3 orbitals, 6 electrons max - D-subshell: 5 orbitals, 10 electrons max - F-subshell: 7 orbitals, 14 electrons max Main group elements: (S and P blocks) Period number= n number D-block elements: period number= (n-1) F-block elements: period number= (n-2) Valence electrons: electrons on the outer most shell Atomic radius: increases going down and to the left in the periodic table Z effffective nuclear charge ZefZ-S - Z is the atomic number - S is the number of inner shell electrons
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