O Chem Chapter 1 Electronic Structure and Bonding.docx

O Chem Chapter 1 Electronic Structure and Bonding.docx - O...

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O Chem Chapter 1 Electronic Structure and Bonding: - Organic: compounds that are based on carbon - Almost all the componds that make life possible (proteins, enzymes, vitamins, lipids, carbohydrates, DNA, RNA, are organic compounds - Many compounds found in nature are organic compounds as well - Many can be synthesized in a lab now - Currently there are 16 million organic compounds known - WHY so many carbon containing compounds?? o C’s position in the periodic table b/c it’s the center of the 2 nd row of elements (atoms to the L give up E- while those to the R accept them) b/c of C’s middle stance, it neither readily gives up or accepts E- insead sharing them w/ several kinds of atoms including C Gives it the ability to form millions of stable compounds w/ a wide range of chemical properties - Organic compounds consist of atoms held by covalent bonds and when these compounds react, some of the covalent bonds break and some new covalent bonds form - How easiliy a bond breaks/forms depends on the E- shared, which depends on the atom they belong to - The Structure of an Atom: - tiny dense nucleus surrounded by E- spread thru a large volume of space in an electron clous - nucleus: contains + protons and neutral neutrons (overall +) - + = - on an uncharged atom - electrons move continuously and have KE which counteracts the attractive force of the + protons that pull the – E- towards them - Protons and neutrons have approx. the same mass and are 1800 x larger than electrons - Mass = nucleus volume = electron cloud - Atomic Number: number of protons in its nucleus (never changes) - Mass Number: sum of protons and neutrons (can vary) - Isotopes: vary in number of neutrons (protons doesn’t = neutrons) - Atomic mass: weighted average of the isotopes in the element (atomic mass unit = 1 amu = 1/12 of the mass of C 12 - Molecular mass: sum of the atomic masses of all the atoms in the molecule
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- Molecule: group of 2 or more atoms held together by bonds How the Electrons in an Atom are Distributed: - Quantum mechanics uses the same mathematical equations of quantum physics (describes wave motions) to describe the motion of an electron around a nucleus - Shells go numerically up 1, 2, 3 further from nucleus - Each shell has subshells called atomic orbitals (has a shape and energy and occupies a certain volume of space) - Each shell contains one s atomic orbital, each second and higher shell has s orbitals also has 3 degenerate p atomic orbitals: orbitals that have the same energy - 3 rd and higher shells in addition to s and 3 p have 5 degenerate d orbitals - 4 th and higher also have 7 degerate f orbitals - a max of 2 E- can coexist in an atomic orbital - 1 st 4 shells w/ 1, 4, 9, and 16 orbitals can house 2, 8, 18, and 32 E- - Ground State Configuration: o Describes the atomic orbitals occupied by the atom’s E- when there are all in the available orbitals w/ the lowest energy o If energy is applied to the atom one or more E- can jump to a higher energy orbital causing the atom to be in an excited state and have an excited-state configuration
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