lecture 1 - Organic Chemistry The study of the compounds of...

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1 Organic Chemistry Organic Chemistry ± The study of the compounds of carbon ± Over 10 million compounds have been identified about 1000 new ones are identified each day! ± C is a small atom it forms single, double, and triple bonds it is intermediate in electronegativity (2.5) it forms strong bonds with C, H, O, N, and some metals Electron Configuration of Atoms • Shells are divided into subshells called orbitals, which are designated by the letters s , p , d , f ,........ s (one per shell) p (set of three per shell 2 and higher) d (set of five per shell 3 and higher) . .... Shell Orbitals Contained in That Shell 3 2 11 s 2 s , 2 p x , 2 p y , 2 p z 3 s , 3 p x , 3 p y , 3 p z , plus five 3 d orbitals Electron Configuration of Atoms • Aufbau Principle: Aufbau Principle: – orbitals fill in order of increasing energy from lowest energy to highest energy • Pauli Exclusion Principle: Pauli Exclusion Principle: – only two electrons can occupy an orbital and their spins must be paired • Hund Hund ’s Rule: s Rule: – when orbitals of equal energy are available but there are not enough electrons to fill all of them, one electron is added to each orbital before a second electron is added to any one of them
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2 Electron Configuration of Atoms • Table The Ground-State Electron Configuration of Elements 1-18 Lewis Model of Bonding ± Atoms bond together so that each atom acquires an electron configuration the same as that of the noble gas nearest it in atomic number an atom that gains electrons becomes an anion an atom that loses electrons becomes a cation cation Lewis Model of Bonding Lewis Model of Bonding the attraction of anions and cations leads to the formation of ionic solids ionic solids an atom may share electrons with one or more atoms to complete its valence shell; a chemical bond formed by sharing electrons is called a covalent bond covalent bond bonds may be partially ionic or partially covalent; these bonds are called polar covalent bonds polar covalent bonds Electronegativity ± Electronegativity: Electronegativity: a measure of an atom’s attraction for the electrons it shares with another atom in a chemical bond ± Pauling scale Pauling scale generally increases left to right in a row generally increases bottom to top in a column Formation of Ions Formation of Ions ± A rough guideline: ions will form if the difference in electronegativity between interacting atoms is 1.9 or greater example: sodium (EN 0.9) and fluorine (EN 4.0) we use a single-headed (barbed) curved arrow to show the transfer of one electron from Na to F
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3 Formation of Ions Formation of Ions in forming Na + F - , the single 3 s electron from Na is transferred to the partially filled valence shell of F +F - (1 s 2 2 s 2 2 p 6 ) Na + (1 s 2 2 s 2 2 p 6 ) F(1 s 2 2 s 2 2 p 5 ) + Na(1 s 2 2 s 2 2 p 6 3 s 1 ) Covalent Bonds Covalent Bonds ± The simplest covalent bond is that in H 2 the single electrons from each atom combine to form an electron pair
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lecture 1 - Organic Chemistry The study of the compounds of...

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