Chemical Bonding Just as the physical and chemical properties of elements are determined by their atomic structure, the properties of compounds are determined by the type of chemical bonding. Valence electrons of atoms are involved in chemical bonding. We will learn 3 types of intramolecular bonding:

Types of Bonding 1. Ionic Bonds form when electrons are TRANSFERRED between atoms with large difference in electronegativity (usually a metal and a nonmetal)

Types of Bonding 2. Metallic Bonds form between metal atoms of the same or different elements. Delocalized valence electrons are attracted to metal cations in the electron sea model.

Properties of Metals Solid (except Hg) Gray/silver colored (except Cu and Au) Luster (shiny) Malleable – mold into shapes Ductile – draw into wires Good conductors of heat and electricity

Metal Properties are the result of Metallic Bonding Metallic bonding video: gMDP47s

Properties of nonmetals Solid, liquid or gas Many different colors Not shiny Not malleable Not ductile Not conductors Properties of metalloids I n between metals and nonmetals (semi-conductors)

Types of Bonding 3. Covalent Bonds involve the SHARING of electrons between atoms with small differences in electronegativity (usually 2 or more nonmetals).

Covalent Bonding Sharing of Electron Pairs: Non-metal with Non-metal Atoms

Compounds that are NOT held together by an electrical attraction, but instead by a sharing of electrons. Occur between nonmetal atoms with electronegativity differences less than 1.67 Covalent Bonding

A neutral group of atoms joined together by covalent bonds is called a molecule. A compound composed of molecules is called a molecular compound. The chemical formula for a molecule is called the molecular formula. Covalent Bonding Molecule NameMolecular FormulaLewis Projection L-tryptophanC 11 H 12 N 2 O 2

Covalent Bonding Properties of Molecular Compounds: Composed of two or more nonmetals. Usually gases or liquids at room temperature. But can be found in any physical state at STP. Molecular compounds tend to have lower melting and boiling points than do ionic compounds. Do not conduct electricity. They form nonelectrolytes. in solution.

Naming Molecular Compounds We use a series of prefixes to indicate the number of atoms: 1 mono 2 di 3 tri 4 tetra 5 penta 6 hexa 7 hepta 8 octa 9 nona 10 deca

Naming Molecular Compounds 1.The first element is the same as the name on the periodic table. Include a prefix only for 2 or more atoms (omit mono). 2.The second element changes the ending to “ide” and always has a prefix (including mono)

Naming Molecular Compounds There are seven elements which exist naturally as two atoms joined together (diatomic molecules). You should memorize them: Have H 2 No N 2 Fear F 2 Of O 2 Ice I 2 Cold Cl 2 Beer Br 2