CHAPTER 1 INTRODUCTION AND REVIEW

SUCROSE, “SUGAR” Chapter 1: Introduction and Review

COMMON MEDICINES ACETYLSALICILIC ACID, ASPIRIN ACETAMINOPHEN, TYLENOL Chapter 1: Introduction and Review

CHOLESTEROL Chapter 1: Introduction and Review

COCAINE Chapter 1: Introduction and Review

ATOMIC STRUCTURE  number of protons determines the element  combinations are possible, with a constant number of protons but varying number of neutrons - ISOTOPES Chapter 1: Introduction and Review

ORBITALS AND SYMMETRY Chapter 1: Introduction and Review

THE BUILDING OF THE ELECTRONIC CONFIGURATION OF ATOMS 1.A maximum of two (2) electrons can be placed in any single orbital (The Pauli’s exclusion principle) 2.Electronic states are occupied in order of increasing energy. 3.Degenerate states (of equal energy!) are first all single occupied (The Hund’s rule).

Lewis’ Octet Hypothesis Atoms will enter into chemical reactions and form bonds with the principle goal to achieve octet configurations of their valence shells

RULES FOR LEWIS STRUCTURES Chapter 1: Introduction and Review Count the total number of electrons available (A) Calculate the total number of necessary electrons (B), in order for each atom to achieve an octet (Hydrogen needs only two electrons!!) Subtract and divide: (B – A)/2 = number of bonds Construct a meaningful structure with the above calculated number of bonds If electrons remain, first assign lone pairs to the terminal atoms, then to the central atoms, wherever necessary Do not forget: Hydrogens are ALWAYS terminal!

ELECTRONEGATIVITY – PAULING’S SCALE Chapter 1: Introduction and Review

RESONANCE STRUCTURES A resonance structure is acceptable if: it is a meaningful Lewis structure (Please refer to rules for writing Lewis structures!) electrons are moved but the skeleton of the molecule is retained A resonance structure has a greater importance if: it contains a greater number of bonds and atom octets it has minimum charge separation the negative charge resides on a more electronegative atom Chapter 1: Introduction and Review

COMMON BONDING PATTERNS Chapter 1: Introduction and Review