Bonding Ionic versus Covalent

Ionic Bonding What is it? Bonding between a metal and a non metal What holds the bonds together? Electrostatic attraction between (+) and (-) “charges” which results from the transfer of the electrons from the least e-neg (metal) to the most e-neg (nonmetal)

What happens to the electrons? One gets (-) the other gives (+). Each resulting ion resembles a noble gas. The (-) resembles the noble gas in the same period. The (+) resembles the noble gas from the period above.

Types of compounds Formula unit a single piece of the crystal lattice or ionic compound. Conductivity Conducts electricity when molten or dissolved in solution. (When ions can move around they can conduct the electric charge)

Electronegativity Large electronegativity differences – greater than 50% or about 1.7 and greater State of Matter Solids with a very strong bond

Other characteristics Ions: elements or group of elements that have a “charge” from an imbalance in + and – Lewis Dot Structure The most e- neg element gets all the electrons show with arrow for e-transfer and ion charge created.

Covalent Bonding

What is it?: Nonmetal + nonmetal What holds the bonds together? Attraction between nuclei of bonding atoms and e- Intermolecular forces: affect the bond polarity and molecular polarity London Dispersion-induced dipole Dipole-dipole Hydrogen bonding Nonpolar: London disp. Only Polar: London disp. And dip-dip with FON to H, hydrogen bonding

What happens to the electrons? The atoms share electrons to look like a noble gas. Nonpolar bonds share electrons evenly. Polar bonds share unevenly depending on electronegativity. What types of compounds? Molecule is single “piece” of a molecular compound.

Conductivity? Does not conduct (no ions – no conduction) Electronegativity? Little electronegativity difference. Nonpolar = less than 0.4 difference. Polar = greater than 0.4 but less than 1.7

States of Matter: All 3 states. Weaker bond: state depends on size of molecule and intermolecular forces. Stronger than ionic bonds. Other: Multiple bonds: C.SON group forms a double, triple bonds. Diatomic molecules: 2 atoms same element bonded together. BrINClHOF

Shapes: VSEPR Valence shell electron repulsion theory – shapes based on shared and lone pair electrons and central atom. Formulas Oxidation State: Find normal charge

Lewis Dot Structure for Covalent Molecules Why: Show how the valence electrons are arranged. Use one dot to represent each valence electron. A stable compound has all its atoms with a noble gas configuration. (8 v.e.) Hydrogen follows the duet rule. (2 v.e.) The rest of the elements follow the octet rule. Bonding pair is the one between the symbols.

How Sum the valence electrons. Draw skeletal structure. Central atom is carbon (if present) or the least electronegative atom Use a pair of electrons to form a single bond between each pair of atoms. Arrange the rest to fulfill the octet rule (except for H and the duet).