Chemical Bonding

Introduction to chemical bonding

CSCOPE Vocabulary: valence electrons oxidation number ion electronegativity ionization energy electron affinity energy levels electron orbitals electron configuration orbital diagrams Lewis dot structures covalent bond ionic bond metallic bond polar non-polar VSEPR theory molecular geometry

Chemical Bonds Chemical Bond – a link between atoms, caused by a mutual attraction of their nuclei for electrons. 3 Types of Chemical Bonds 1) Ionic Bond (metal---nonmetal) 2) Covalent Bond (nonmetal---nonmetal) 3) Metallic Bond (metal---metal)

Elements and Compounds

Ionic Bonds Ionic Bonds – involve a transfer of electron(s) between two atoms. One atom becomes negative(anion) and the other positive(cation). The opposite charges of the ions formed causes them to attract. Ionic bonds usually occur between a metal(+) and a nonmetal(-) ion. *Ionic substances are also called salts(minerals) and have high melting pts and high boiling points because ions arrange in a repeating pattern called a crystal lattice. *Groups of ions are called formula units.

IONIC BONDS

Covalent Bonds Covalent bonds involve a sharing of electron pairs between two neutral atoms. Covalent bonds are usually between two nonmetals. Covalent compounds have low melting points and boiling points, because atoms form individual groups called molecules that are held together by weaker intermolecular forces of attraction. *Groups of atoms held together by covalent bonds are called molecules.

COVALENT BONDS

Ionic and Covalent Bonding

Dogs Teaching Bonding

Metallic Bonds Metallic bonds involve two or more metal atoms. The positive metal nuclei stay in a fixed position, with free-flowing electrons between them. These “free-flowing” electrons are called delocalized electrons. These loosely held electrons allow metals to be: Good electrical conductors, malleable(bendable), and ductile(drawn into wires.)

METALLIC BONDS

Predict the type of bond: C---O Mg---S N---Na P---O Li---F Br--Br Rb--Cl S—Fe S—Ba Cl--S

The truth about ionic and covalent bonding…. Most substances are either mostly ionic or mostly covalent, but rarely truly ionic or truly covalent!!!!! To determine the character of a bond (or substance), one must subtract the electronegativities of each atom in a bond.

The Pauling Electronegativity Values

Electronegativity Difference The electronegativity difference between two atoms will determine the bond character of a compound. Electronegativity Difference 0.0------------------1.7---------------4.0 I Covalent I ionic I 0.0-Nonpolar-0.3-Polar------------------->4.0

Determine the bond character between: C---O Mg---S N---Na P---O Li---F Br--Br Rb--Cl S—Fe S—Ba Cl--S