Chapter 1 Organic Chemistry Electronic Structure 5th Edition and Bonding Acids and Bases Organic Chemistry 5th Edition Paula Yurkanis Bruice Amy Parente Penn State Altoona Altoona, PA

Introduction Some History… Organic = compounds derived from living organisms and believed to contain an unmeasurable vital force Inorganic = compounds derived from minerals and lacking vital force 1828 - Friedrich Wöhler synthesized urea in the laboratory: Organic = compounds that contain carbon Why study Organic Chemistry? Nearly all life’s molecules (proteins, enzymes, vitamins, lipids, carbohydrates, and nucleic acids) contain carbon Chemical reactions that take place in living systems are reactions of organic compounds

Introduction All about carbon…why is it so special? Carbon has a unique position on the periodic table - center of the second row Tendency to give up electrons (e-) Carbon likes to share electrons Tendency to accept electrons (e-) Carbon shares electrons with other carbon atoms, as well as with several kinds of atoms Millions of stable compounds (~16 million known organic compounds) Bonds form when 2 atoms share electrons - the extent of sharing depends on atoms to which the electrons belong - we must begin by understanding the atom

1.1 - The Structure of an Atom The Atom… Dense nucleus that is positively charged and contains most of the atom’s mass Charge due to presence of protons - positively charged subatomic particles Mass due to presence of protons and neutrons Fast moving negatively charged electron cloud that comprises most of the atom’s volume Charge due to presence of electrons - negatively charged subatomic particles High energy environment prevents the negatively charged electrons from collapsing into positively charged nucleus Abbreviations: Protons - p+ Electrons - e- Neutrons - no

1.1 - The Structure of an Atom Atomic number = 핵 안의 양성자수 = 중성원자의 전자 수 Mass number = 양성자수 + 중성자수 Isotope(동위원소) : 원자번호는 같고 중성자수 다르다. 질량수 다르다.

1.2 - Distribution of Electrons in an Atom P5 1.2 - Distribution of Electrons in an Atom 고전역학 : Newton 역학 거시적 세계 에너지의 연속성 현대역학 : 양자역학 미시적 세계 에너지의 불연속성

현대 원자론: 에너지 파동 역학적 모형 ▪ 전자의 파동성과 그 위치의 불확실성으로 인해, 수소 원자의 전자에 대하여 파동 역학(wave mechanics)이라고 알려진 복잡한 수학적 접근을 하게 되었다.

Schrodinger Wave Equation In 1926 Schrodinger wrote an equation that described both the particle and wave nature of the e- Wave function (Y) describes: . Energy of e- with a given Y 2. Probability of finding e- in a volume of space Schrodinger’s equation can only be solved exactly for the hydrogen atom. Must approximate its solution for multi-electron systems.

1. 주 양 자수(principal quantum number) n Schrodinger Wave Equation의 해: 원자내의 전자의 배열을 기술하는데 사용 ----양자수가 결정 Y = fn(n, l, ml, ms) 1. 주 양 자수(principal quantum number) n n=3 n = 1, 2, 3, 4, …. n=2 n=1 궤도함수의 크기결정

Where 90% of the e- density is found for the 1s orbital

Schrodinger Wave Equation Y = fn(n, l, ml, ms) 2. 부양자수, 각 운동량 양 자수 angular momentum quantum number l for a given value of n, l = 0, 1, 2, 3, … n-1 l = 0 s orbital l = 1 p orbital l = 2 d orbital l = 3 f orbital n = 1, l = 0 n = 2, l = 0 or 1 n = 3, l = 0, 1, or 2 궤도함수의 모양

l = 0 (s orbitals) l = 1 (p orbitals)

l = 2 (d orbitals)

Schrodinger Wave Equation Y = fn(n, l, ml, ms) 3.자기 양 자수 (magnetic quantum number) ml for a given value of l ml = -l, …., 0, …. +l if l = 1 (p orbital), ml = -1, 0, or 1 if l = 2 (d orbital), ml = -2, -1, 0, 1, or 2 궤도함수의 공감배치

ml = -1 ml = 0 ml = 1 ml = 1 ml = 2 ml = -2 ml = -1 ml = 0

Schrodinger Wave Equation Y = fn(n, l, ml, ms) 4. 스핀 양 자수(spin quantum number ) ms ms = +½ or -½ ms = +½ ms = -½

P5 first shell second shell Third shell

원소의 전자 배치 전자배치를 위한 규칙 1. 쌓음 원리(Aufbau principle) 2. Pauli 배타 원리(Pauli exclusion principle) 3. Hund의 규칙(Hund’s rule)

( ) Energy of orbitals in a single electron atom 1 En = -RH n2 Energy only depends on principal quantum number n n=3 n=2 En = -RH ( ) 1 n2 n=1

Energy of orbitals in a multi-electron atom Energy depends on n and l n=1 l = 0 n=2 l = 0 n=2 l = 1 n=3 l = 0 n=3 l = 1 n=3 l = 2

Order of orbitals (filling) in multi-electron atom 1s < 2s < 2p < 3s < 3p < 4s < 3d < 4p < 5s < 4d < 5p < 6s ---

전자 껍질과 부껍질에 전자 배당

1.2 - Distribution of Electrons in an Atom P7

1.3 - Ionic and Covalent Bonds P9 결합은 왜 하는 것일까? Lewis Theory - an atom is most stable if its outer shell is either filled or contains eight electrons, and it has no electrons of higher energy - octet rule 이온결합 1) Electropositive elements - atoms that readily lose electrons Lewis structures - valence electrons are shown as dots around a single atom

2)Electronegative elements - atoms that readily acquire electrons P9 2)Electronegative elements - atoms that readily acquire electrons

Cations and Anions Of Representative Elements +1 +2 +3 -3 -2 -1

전자의 전달에 의해 형성되는 이온결합

An ionic bond is a result of only electrostatic attractions and is formed when there is a transfer of electrons causing one atom to become a positively charged ion and the other to become negatively charged ion. P 10 전자풍부 전자부족 NaCl 결정

Why should two atoms share electrons? P 10 공유 결합 ▪ 두 원자 사이에 두 개의 전자를 공유하는 것을 공유 결합 (covalent bond)이라고 한다. Why should two atoms share electrons? 7e- 7e- 8e- 8e- Lewis structure of F2 F F + F

Hydrogen is unique (only 2 valence electrons): The “octet” rule can be satisfied by either sharing a single electron, losing a single electron, or gaining a single electron:

What about atoms that need more than 1 electron to fill their valence shell? More than one bond!

1.3 - Ionic and Covalent Bonds P11 Electronegativity - measure of the ability of an atom to pull bonding electrons towards itself

P 12 비극성 공유결합 극성 공유결합