Chapter 16 Section 1 Molecular Compounds -generally have low melting and boiling points -most are gases or liquids at room temp -do not conduct an electric current when dissolved in water -made up or two or more non-metals

Covalent Bonding -electrons are shared between atoms -each element still is trying to achieve octet *except hydrogen* -hydrogen only needs 2 valence e- single covalent bond- two atoms share a pair of electrons -bonds (pair of e-) are represented as dashes (─)

Ex- H· + H·  H:H  H-H  H 2 simple formula- shows # and type of atoms ex- H 2 structural formula- shows arrangement of atoms in a molecule ex- H-H

-combos of atoms of the nonmetallic elements in Groups 4-7 are likely to form molecules *also hydrogen bonding pairs/shared pairs- pair of e- shared between two atoms lone pairs/unshared pairs- electrons not involved in bonding ex- Cℓ 2

double covalent bond- bond that involves two shared pairs of e- (═) triple covalent bond- bond that involves three shared pairs of e- (≡)

resonance structures- two or more valid Lewis structures example: **Write resonance structures for sulfur dioxide

-Lewis structures make it seem as though e- are shared equally between the elements of covalent bonds -this is not the case Ex- HF -H has a slight positive charge and F has a slight negative charge

these bonds are said to be polar- having a slightly + and slightly – pole polar covalent bond- intermediate in nature between a pure covalent and an ionic bond -the degree of polarity in bonds depends on electronegativity difference (∆EN) between the elements -table 14.2 page 405

Effect of ∆EN on Bond Type: ∆ENBond Type Example Nonpolar Covalent Cℓ Polar Covalent HCℓ ≥ 2.0Ionic NaCℓ Page 462 Sample Problem 16-4