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Organic Chemistry

Organic Chemistry. Unit 1 – Atomic and Molecular Structures (Bonding Review). The Atom. 2 Parts = Nucleus and electron (e-) cloud Nucleus – small, dense positively charged region in the center of the atom (almost all of its mass and none of its volume )

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Organic Chemistry

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  1. Organic Chemistry Unit 1 – Atomic and Molecular Structures (Bonding Review)

  2. The Atom • 2 Parts = Nucleus and electron (e-)cloud • Nucleus– small, dense positively charged region in the center of the atom (almost all of its mass and none of its volume) • e- Cloud– area surrounding the nucleus where the e-s may be found

  3. The Electron Cloud • e- = negatively charged subatomic particle found outside the nucleus • e-’s are found in energy levels (shells ) from 1  ? • shells are divided into sublevels (subshells) • shells contain orbitals (3-d region around the nucleus where an e- may be found)

  4. Electron Shells

  5. Orbital Review • SPDF – 2 e-s per orbital – with opposite spins! • s = 1, p = 3, d = 5, f = 7) • Quantum Numbers (QN) • Principal QN – n= E level • Angular Momentum QN – l= shape • Magnetic QN – m= orientation • Spin QN – direction

  6. Electron Configurations • 1. Pauli Exclusion Principle – no 2 e-‘s in the same atom can have the same set of 4 quantum numbers • The two e-‘s in an orbital have to have opposite spins ( ) • 2. AufbauPrinciple – an e- will occupy the lowest E orbital that can accept it • 3. Hund’sRule – orbitals of equal E must each have 1 e- before any can get 2

  7. Electron Configurations • Writing e- configurations : we use orbital notation & e- config. Notation • Principal QN = n 2n2 = # e-‘s in an e- shell • Try the configurations for Na, O, Fe, and Xe • Try the orbital notation (orbital diagrams) for the same elements listed above. • Some exceptions in Transition, 4f, and 5f

  8. Stability • Atoms try to become stable by filling their outer e- shell (8e-‘s) • Octet = full shell of 8 e-‘s in the outer shell (s & p orbitals) • Full octet = Noble Gas Configuration • Elements form compounds to gain octet configurations • Either transfer outer shell e-‘s to form ionic bonds, or by sharing e-‘s to form covalent bonds

  9. Noble Gas Notation • Used for elements beyond K • Practice the NGN for Ni, Sn, and Ba

  10. Electron Dot Symbols (Lewis Structures) • Show outer e-’s (s and p orbitals) • Used to show chemical bonds • Draw the next chart in your notebook and fill in the blanks with the correct information 

  11. Lewis Structures

  12. Lewis Structures

  13. LS for Molecules • Ionic Bonds are formed by metals from Groups I, II, or III giving e-’s for nonmetals from Groups VI, VII, or VII • Try the LS and Orbital Diagrams for K2S, Na3N, and CaF2

  14. Bonding • Gr I = bonds ns1 • Gr II = bonds *ns1np1 • Gr III = bonds * ns1np2* = • Gr IV = bonds * ns1np3excited State • Group V = bonds ns2np3 • Group VI = bonds ns2np4 n = E Level • Group VII = bonds ns2np5 (Outer Shell) Why promote an s e-?

  15. Bonding Examples • Try AlI3, Ca3N2, SrS

  16. Covalent Bonding • Covalent bonds are formed when Groups IV – VII (and H) share outer shell e-s so each atoms gets 8 e-s (except H can only get 2 e-s) • There are 4 kinds of covalent bonds (right now = look at 3 of them) • Remember diatomic elements NOAH

  17. Covalent Bonding • Single Covalent Bond – one pair of e-s shared between 2 atoms • F2 • Lewis Structure = • Orbital Diag. =

  18. Covalent Bonding • Double Covalent Bond – two pairs of e-s shared between 2 atoms • O2 • Lewis Structure = • Orbital Diag. =

  19. Covalent Bonding • Triple Covalent Bond – three e- pairs shared between 2 atoms • N2 • Lewis Structure = • Orbital Diag. =

  20. Covalent Bonding • When Drawing Lewis Structures for covalent structures, start with only 2 atoms and add alternatively as you need them • NCl3

  21. Homework! • Complete the following Lewis Structures for Covalent Compounds for homework: • H2O/ SBr2/ CBr4/ NP/ CO2/ N2O3/ Na2Te/ BaSe

  22. Polyatomic Ions • We can also take the same approach with polyatomic ions • Polyatomic Ion– covalently bonded group of atoms that carries a net charge • Negative polyatomic ions are formed by H+ ions leaving an oxyacid • Oxyacid – an acidic substance that contains oxygen • Positive polyatomic ions are formed by H+ ions bonding coordinately to a neutral molecule

  23. In Class Assignment • Do the Lewis Structures for the following… • [HSO4-/ SO4-2/ H2PO4-/ HPO4-2/ PO4-3/ HCO3-/ NO3-/ IO3-/ CO3-2/ NH4+/ PH4+/ H3S+/ H2Cl+/ H4I3+]

  24. Last Covalent Bonding Type • Coordinate Covalent Bond – a bond where both shared e-s are from the same species • (bond between a Lewis acid and a Lewis Base)

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