Chemical Bonding

To Predict the nature of a chemical bond using electronegativities How to form ions to stable electron configurations How to predict physical properties based upon bonding (mp, etc.)‏ How to write Lewis Structures and multiple bonding What is VSEPR Theory, and how is it used to predict the geometry of a molecule What is Bond Polarity and how do we predict solubility in polar and non-polar solvents

Force that holds two atoms together Formed by the attraction of a positive ion for a negative ion or by sharing electrons.

Ionic Radius K Cl- K+ Cl Anions Negative Ion (O2- ) Non-metals Cations Anions Positive Ion (Be 2+) Metals Lose electrons Radius gets smaller! Negative Ion (O2- ) Non-metals Add electrons Radius gets larger! K Cl- K+ Cl

Periodic Table Organization Metalloids Metals Non-Metals

Metals and Non-metals Non-metals Metals Dull Brittle Poor conductors Shiny Malleable Ductile (pulled into wires) Conduct heat and electricity Low specific heat High mp / bp Solids Lose electrons Dull Brittle Poor conductors Low melting/boiling points Varied properties Varied phases

Reaction of a metal with a non-metal Transfer of Electrons Metal loses electron/s Non-Metal gains Bond is an electrostatic attraction of ions Cation (+)‏ Anion (-)‏ Ionic Bonds

Ionic Compounds Conducts electricity Crystal lattice – strong forces High mp and bp Hard – not easily crushed

Metals and Non-metals Non-metals Metals Dull Brittle Poor conductors Shiny Malleable Ductile (pulled into wires) Conduct heat and electricity Low specific heat High mp / bp Solids Lose electrons Dull Brittle Poor conductors Low melting/boiling points Varied properties Varied phases

Covalent Compounds Weaker forces between molecules Odor – volatile liquids and gases– evaporates easily Lower mp and bp Softer compounds – more easily ground into powder

Covalent Bonding Reaction of two or more non-metals Sharing Electrons Bond is attraction of nuclei to shared electrons

Electronegativity Increases Pull of electrons in a covalent bond “Attraction” of atoms towards an electron Fluorine is “the man” Electronegativity Increases

Nature of a chemical bond Use difference in electronegativities to predict type of bonding Nature of a chemical bond 100 % 3.40 1.70 0.00 50 % 0 % Ionic Character 0.40 Ionic Non-polar Covalent Polar Covalent

Identify each of the following as either ionic, polar covalent, or non-polar covalent Fr 0.6 Li 1.0 Na 0.9 H 2.1 C 2.5 O 3.5 Br 2.8 F 4.0 Cl 3.0 LiF CO2 NaCl HCl Fr2O FrF CH4 NaBr 4.0 – 1.0 = 3.0 > 1.7 -- Ionic 3.5 – 2.5 = 1.0 < 1.7 – Polar Covalent 3.0 – 2.1 = 0.9 < 1.7 – Polar Covalent 3.0 – 0.9 = 2.1 > 1.7 -- Ionic 4.0 – 0.6 = 3.4 > 1.7 -- Ionic 3.5 – 0.6 = 2.9 > 1.7 -- Ionic 2.5 – 2.1 = 0.4 = 0.4– Nonpolar 2.8 – 0.9 = 1.9 > 1.7 -- Ionic

Reaction of a Metal and Non-Metal Transfer of electrons from the metal to the non-metal to form noble gas electron configuration example Na + Cl Na+ Cl - ▪ : Metal Loses Non-Metal Gains

K + + F - : : Sr+2 + O -2 : Al+3 + N -3 : : 2 K+ + O -2 : : Write the equation for each reaction using Lewis Dot Structures: Octet Metal loses; Non-metal gains K + F Sr + O Al + N K + O + K Cl + Ca + Cl : : ▪ K + + F - Sr+2 + O -2 Al+3 + N -3 2 K+ + O -2 Ca+2 + 2 Cl -1 ▪ : ▪ : : : ▪ : ▪ : : ▪ : ▪ ▪ : : ▪ : ▪ :

Conducts electricity in aqueous solution Brittle High Melting Strong attraction between ions Conducts electricity in aqueous solution ELECTROLYTE Conducts electricity in the molten state Ions become mobile