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Quantum Numbers. n, l, m, and s Used to describe an electron in an atom Probable location n Principal Quantum Number Represents main energy level of electron Maximum # o f electrons in an energy level = 2n 2
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Quantum Numbers • n, l, m, and s • Used to describe an electron in an atom • Probable location • n • Principal Quantum Number • Represents main energy level of electron • Maximum # of electrons in an energy level = 2n2 • Example: What is the maximum number of electrons that can be in the 5th main energy level? • 2(52) • Electrons in 7th energy level? Episode 304
Quantum Numbers • l • The 2nd quantum number • Angular momentum quantum number • Describes the orbital shape within an energy level • Number of orbital shapes possible in an energy level = n http://www.youtube.com/watch?v=K-jNgq16jEY&list=PLD1C287B0E1484083&index=9&feature=plcp Episode 304
Orbital Shapes • Designated s, p, d, and f • Level 1: s • Level 2: s, p • Level 3: s, p, d • Level 4: s, p, d, f Episode 304
How many electrons can each sublevel hold? • 2 e- • 6 e- • 10 e- • 14 e- • s = 1 orbital x 2 e-/orbital = • p = 3 orbitals x 2 e-/orbital = • d = 5 orbitals x 2 e-/orbital = • f = 7 orbitals x 2 e-/orbital = Energy Level n E sublevel Type of orbital # of orbitals # e- in orbital # e- = 2n2 s 1 2 1 2(12) = 2 s 1 2 2 2(22) = 8 p 3 6 Episode 304
Quantum Numbers • m • The 3rd quantum number • Magnetic Quantum Number • Describes the orientation of the orbital in space Episode 304
Quantum Numbers • s • The 4th quantum number • Spin Quantum Number • Describes the spin of the electron in orbital • Ground state • Lowest energy arrangement of electrons • Aufbau Principle http://www.youtube.com/watch?v=2ypC7rnFXLU&list=PLD1C287B0E1484083&index=1&feature=plcp Episode 304
Diagonal Rule Examples: • Hydrogen • 1 electron • 1s1 • Lithium • 3 electrons • 1s2 2s1 • Nitrogen • 7 electrons • 1s2 2s2 2p3 Episode 304
Electron Configurations • Describes the electron distribution within an atom • Longhand electron configuration • Nitrogen 1s22s22p3 • Orbital Notation • Uses arrows to represent electrons • Examples: • Hydrogen 1s1 1s Episode 304
Nitrogen • 1s2 2s2 2p3 • Hund’s Rule • Orbitals of equal energy are each occupied by one electron before any orbital is occupied by a second electron (spinning in opposite direction) • Pauli Exclusion Principle • No two electrons in the same atom can have the same set of 4 quantum numbers 1s 2s 2p Episode 304