CHEM 1131 1st EditionExam # 2 Study Guide Chapters: 3-5Chapter 3: Quantum Theory and the Electronic Structure of AtomsKinetic/Potential EnergyKinetic Energy: the energy that results from motion. - thermal energy: the energy associated with the random motion of atoms and moleculesPotential Energy: the energy possessed by an object by virtue of its position.- chemical energy: energy stored within the structural units of chemical substances. - electrostatic energy: potential energy that results from the interaction of charged particles.Law of Conservation of EnergyWhen energy of one form disappears, the same amount of energy must appear in another form or forms.Properties of WaveWavelength (λ ¿: the distance between identical points on successive waves. Different wavelength – colorFrequency (ν ¿ : the number of waves that pass through a particular point in 1 second. Different amplitude – brightnessAmplitude: the vertical distance from the midline of a wave to the top of the peak or the bottom of the trough. c = speed of light through a vacuum. 3.00*108 m/sThe Bohr Equation Electron dropping from higher energy orbit to lower one/ground state ⟶ gives up a quantum of energy in form of light. n = energy level/state. The energy gap between the initial (ni ) and final (nf) determines the wavelength (color) of light emitted. Electromagnetic SpectrumGamma, X-rays, Ultraviolet, Visible light, Infrared, Microwave, Radio waves ⟶ wavelength ⟵ frequency (order of increasing wavelength/decreasing frequency)Basis of Quantum theory Max Plank – radiant energy could be emitted or absorbed only in discrete quantities, which means light is quantized. Quantum: the smallest quantity of energy that can be emitted (or absorbed) in the form of electromagneticradiation. The energy E of a single quantum of energy is h: Plank’s constant 6.63*10-34 J.sPhotoelectric EffectElectrons are ejected from the surface of a metal exposed to light. However, light should be of a certain minimum frequency, called the threshold frequency. Below threshold frequency⟶ no electrons ejected.Wave property of Electronde Broglie hypothesis: an electron does behave like a standing wave in the hydrogen atom; the wavelength must fit the circumference of the orbit exactly. Heisenberg UncertaintyIt is impossible to know simultaneously both the momentum p (defined as mass times velocity, m*u) and the position x of a particle with certainty. Electron DensityElectron density gives the probability that an electron will be found in a particular region of an atom. The square of wave function Ψ 2 ⟵ distribution of electron density in three dimensional space around the nucleus. HIGH electron density = HIGH probability of locating the electron. Quantum numberThe principal quantum number (n) – designates size, energy, levelAngular momentum quantum number (l) – describe type/shape on the value of n. Also called azimuthal quantum number.The magnetic quantum number (ml) – specifies orientation. –l,0,+lSHOOT electron!! Higherenergy than W can give kinetic energyW: binding energym: mass u: velocityElectron spin quantum number (ms) - +1/2 or -1/2e.g. 2p2 = n:2 l:1 ml: -1 ms: -1/2 or +1/2Energy of Orbitals1s<2s=2p<3s=3p=3d<4s=4p=4d=4fElectron Configuration and Pauli exclusion principlePauli Exclusion principle: no two electrons in an atom can have the same four quantum numbernumbers. Hund’s Rule⟵ orbital diagram for a helium atom inthe ground state (one in which all the electrons occupy orbitals of the lowest possible energy.)The most stable arrangement of electrons in orbitals of equal energy is the one in which the number of electrons with the same spin is maximized. An electron will occupy an empty orbital rather than one that already contains an electron.e.g. Aufbau principleProcess of writing electron configuration based on the order of orbital energies / the Pauli exclusion principle. It makes it possible to build the periodic table of the elements and determine their electron configuration by steps.Electron Configuration using Periodic TableThe electron Configuration of elements can be written using a noble gas core except hydrogen and heliumEXCEPTION: some metals tend to achieve half filled (e.g. 3d5) or completely filled (e.g.3d10) subshell. e.g. Chromium (z=24) : [Ar] 4s13d5 instead of [Ar] 4s23d4Chapter 2move one electron from s sublevel to d to get half filled dElements arranged in the periodic table.1st – arranged in order of increasing atomic masslater – in order of increasing atomic numbersame group has similar properties because they have same valence electronsCharacteristics of element in terms of locationValence electrons = how atoms interact each other. Elements in in same group have similar properties since they have same number of valence electrons (exception: group 4); Valence electrons equal group number. e.g. Br is in group 7A. Thus, bromine has 7 valence electronsGroup 1A-7A: main group element. Group 8A: Noble gas ; completely filled p subshell. ns2np6 Group 1B-8B: transition metal; incompletely filled d subshells.Lanthanides & actinides: incompletely filled f block. 1A: Alkali metal; [noble gas core]ns12A: Alkali earth metal; [n]ns27A: halogen; ns2np5Utilize the periodic table to determine the electron configuration Add electrons in order as you move right e.g. 3s23p1, 3s23p2Energy level (n) increasesENS, AR, IE, EAEffective nuclear charge (Zeff): the actual magnitude of positive charge that is experienced by an electron in the atom. Atomic radius: the distance between the nucleus of an atom and its valence shellIonization energy: the minimum energy required to remove an electron from an atom in the gasphase. The result = ion. Electron affinity: the energy released when an atom in the gas phase accepts an electron.Characteristics of Metals, Nonmetals, and metalloids. Metals: tend to lose electrons to be like noble gas; shiny, lustrous, malleable and ductile; good conductors of both heat and electricity; have low ionization energy; Nonmetals: tend to gain more electrons to be like noble gas; poor conductor of heat.Metalloid: elements with properties intermediate between those of metals and nonmetals.The charge of an ion from a main group element. Since main group elements tend to be like noble gas, they lose or gain electrons (become ion) asmuch as they need to have same number of electrons