Properties of Electromagnetic Radiation 1. What is spectroscopy, a continuous spectrum, a line spectrum, differences and similarities 2. Relationship of wavelength to frequency, relationship of E to λ and v 3. Speed of light 4. Types of EMR, relative order of wavelength 5. Relative order of colors, range of wavelength 6. What causes us to see material as colored? (what is an electron doing to cause our eye to see that color) 7. Conversion of wavelength units Particle Behavior of Light 1. Calculate the energy of a photon, mole of photons 2. Find binding energy of an electron (know KE) 3. What is a quanta? Bohr Model of the Hydrogen Atom 1. How does Bohr describe an atom? 2. Calculate the energy of the electron in an orbit 3. Is the atom absorbing or emitting light when an electron changes orbit? 4. Calculate the energy needed to cause a transition (ΔE) 5. Know the sign of ΔE for emission vs. absorption 6. Know the definition of the energy of an electron (E given off when an electron is put into an orbital) Dr. Lori Stepan Van Der Sluys 1 Chapter 6 Part 3 Dr. Lori Stepan Van Der Sluys 2 Chapter 6 Part 3
Chapter 6 Part 3; Many-electron atoms Read: BLB 6.7 6.9 HW: BLB 6:59, 63, 67, 71b-d, 74, 75, 90, 97 Packet 6:11-15 Know: Orbitals & atoms with many electrons Spin quantum number m s o Pauli exclusion principle o Hund's Rule Electron Configurations using periodic table What is the Exam 1 Date and Time? What is the next Skill Check Test Deadline? Form a study group, use the CRC, use the online resources, and work those problems---practice, practice, practice Summary Orbitals Allowed for electrons in atom. Describes of electrons in these energy states. Orbital number shape? name of orbitals? ------------------------------------------------------- s p d f QUANTUM NUMBERS defines? n principal l azimuthal (angular momentum) m l magnetic Dr. Lori Stepan Van Der Sluys 3 Chapter 6 Part 3 Dr. Lori Stepan Van Der Sluys 4 Chapter 6 Part 3
How are shells, subshells and orbitals related to energy? Orbital Energy Levels in the Hydrogen Atom Shells, Subshells and Orbitals LRSVDS Chem 110 Chapter 6 Part 3 5 LRSVDS Chem 110 Chapter 6 Part 3 6
Orbital Energy Levels in Many Electron Atoms ORBITAL ENERGIES Orbital energy is: the energy needed to remove an electron from the orbital (positive) or the energy released when an electron goes into the empty orbital (negative). H atom: Energy does not depend on l or m l 2 1 E( n) = RH n 1 e atom with nuclear charge Z (He +, Li +2 ) What is Z? Z = Multi-electron atom: where Z eff = effective nuclear charge Why? LRSVDS Chem 110 Chapter 6 Part 3 7 LRSVDS Chem 110 Chapter 6 Part 3 8
Screening and Effective Charge See section 7.2 Shielding Affects the Ordering of Energy Levels Electrons in inner orbitals act as screens for outer electrons. This is also called shielding. Outer electrons experience a lesser nuclear charge (less attraction), called effective charge (Z eff ) Approximate: Z eff Z S where S = General Trends in Screening For a given shell (fixed n) s orbital has electron density at nucleus (sees larger Z eff ) and has lower energy p orbital has no electron density at the nucleus and has higher energy screening increases: s < p < d E increases: E s < E p < E d How do the electrons fill the orbitals? In which order? How many electrons can go into an orbital? LRSVDS Chem 110 Chapter 6 Part 3 9 LRSVDS Chem 110 Chapter 6 Part 3 10
Electron spin Stern-Gerlach experiment of An Electron an electron in an atom is described by quantum numbers: Pauli exclusion principle: no two e in an atom can have the same four quantum numbers Consequences of the Pauli exclusion principle: each orbital can have a maximum of two e, each with opposite spin neutral atoms (electrons) seem to possess magnetic moment that is quantized enter another quantum number spin magnetic quantum number: (m s ) m s = + up m s = down More Complete Description # of maximum # subshell orbitals of electrons s (l = ) p (l = ) d (l = ) f (l = ) Look at the periodic table! LRSVDS Chem 110 Chapter 6 Part 3 11 LRSVDS Chem 110 Chapter 6 Part 3 12
ELECTRON CONFIGURATIONS Orbitals are filled sequentially, lowest energy orbitals fill first: Aufbau principle (or building up principle) Hund s rule fill a set of degenerate orbitals (subshells) to produce maximum number of spins (parallel) H Li Na He Be B C N O F Ne Now we have a problem: What is the electron configuration of carbon? Carbon 1s 2 2s 2 2p 2 1s 2 2s 2 2p x 2p y 2p z or 1s 2 2s 2 2p x 2p y 2p z minimizes electron-electron repulsions, thereby energy LRSVDS Chem 110 Chapter 6 Part 3 13 LRSVDS Chem 110 Chapter 6 Part 3 14
Electron Configurations past First Row LRSVDS Chem 110 Chapter 6 Part 3 15 Ne 1s 2 2s 2 2p 6 [Ne] Na 1s 2 2s 2 2p 6 3s [Ne]3s Mg [Ne] 3s 2 Al [Ne] 3s 2 3p Si [Ne] 3s 2 3p 2 P [Ne] 3s 2 3p 3 S [Ne] 3s 2 3p 4 Cl [Ne] 3s 2 3p 5 Ar [Ne] 3s 2 3p 6 filled subshell K [Ne] 3s 2 3p 6 4s new shell (row) Ca [Ne] 3s 2 3p 6 4s 2 Ca 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 [Ar] 4s 2 Core valence or or inner-shell outer-shell electrons electrons LRSVDS Chem 110 Chapter 6 Part 3 16
Transition Metal Electron Configurations 4s fills 3d Exception: Cr and Cu (know these 2 exceptions!); Sc [Ar] 4s 2 3d 1 Ti [Ar] 4s 2 3d 2 V [Ar] 4s 2 3d 3 Cr [Ar] 4s 1 3d 5 half filled subshells Mn [Ar] 4s 2 3d 5 Fe [Ar] 4s 2 3d 6 Co [Ar] 4s 2 3d 7 Ni [Ar] 4s 2 3d 8 Cu [Ar] 4s 1 3d 10 filled d-subshell Zn [Ar] 4s 2 3d 10 Order of Orbital filling 1s 2s 2p 3s 3p 3d 4s 4p 4d 4f 5s 5p 5d 5f 6s 6p 6d know the first row of transition metals as well as main group LRSVDS Chem 110 Chapter 6 Part 3 17 LRSVDS Chem 110 Chapter 6 Part 3 18
Electron Configuration and the Periodic Table Electron Configurations of the Elements LRSVDS Chem 110 Chapter 6 Part 3 19 Location on Periodic Table is related to electron configuration Elements in the same column (family) have the same valence shell configuration. Example: alkali metals (column 1) have what valence electron configuration? (H) 1s 1 Li [He] 2s 1 Na [Ne] 3s 1 K [Ar] 4s 1 Rb [Kr] 5s 1 Cs [Xe] 6s 1 halogens (F, Cl, Br, I) have outer shell noble gases (inert) have filled outer shell of Valence electrons determine the chemistry! LRSVDS Chem 110 Chapter 6 Part 3 20
Electron Configurations of the Elements LRSVDS Chem 110 Chapter 6 Part 3 21