Bonding Chapter 13 (part 1) Web-site:

Bonding – ch Define electronegativity 2. Rank the following in order of electronegativity: a. Cl Br I b. Al Si P

Bonding – ch Consider the following bonds to determine the following: C-O C-Br C-S a. Most polar bond b. Most ionic character c. Longest bond

Bonding – ch Fill in the following table: Substance # of Valence electrons Lewis Structure H 2 CO N2F2N2F2 SO 3 ClO 4 - H 3 PO 4 XeF 4

Bonding – ch Estimate the value of ΔH for the following reactions: a. CH Cl 2  CCl HCl b. Formation of ammonia Bond Ave. Bond Energy (kJ/mol) Bond Ave. Bond Energy (kJ/mol) H-H432C-Cl339 C-H413N-H391 Cl-Cl239N=N418 H-Cl427N≡N941

Bonding – ch 13 Lewis Structure Guidelines: 1. Determine the number of valence electrons (group number, add electrons for anions or subtract electrons for cations) 2. Determine the central atom(s) – least electronegative element (exception - hydrogen will not be the central atom) 3. Draw out structure with single bonds symmetrically 4. Subtract the bonding electrons from the valence electrons – place the remainder on the outer atoms before central atoms – H (wants 2e-), Be (wants 4e-), B and Al (wants 6 e-), all else (wants 8e-) 5. Once you’ve run out of electrons determine if all atoms have what they want – if yes you’re done – if not add a bond for every 2e- that’s missing – the bonding electrons come from the adjacent atoms non-bonded pair 6. Formal Charge = Group number – #bonds – #non-bonded electrons Lewis Structure Guidelines: 1. Determine the number of valence electrons (group number, add electrons for anions or subtract electrons for cations) 2. Determine the central atom(s) – least electronegative element (exception - hydrogen will not be the central atom) 3. Draw out structure with single bonds symmetrically 4. Subtract the bonding electrons from the valence electrons – place the remainder on the outer atoms before central atoms – H (wants 2e-), Be (wants 4e-), B and Al (wants 6 e-), all else (wants 8e-) 5. Once you’ve run out of electrons determine if all atoms have what they want – if yes you’re done – if not add a bond for every 2e- that’s missing – the bonding electrons come from the adjacent atoms non-bonded pair 6. Formal Charge = Group number – #bonds – #non-bonded electrons

Bonding – ch Compare the relative stabilities of the resonance structures for SCN -

Bonding – ch Rank the following in order of relative carbon oxygen bond length: CH 3 OH CO 2 CO CO 3 2-