AlCl3 Aluminum Chloride WHAT TYPE OF BOND DO ALUMINUM AND CHLORINE FORM? Water sugar salt We are going to talk about bonding Bonding between atoms is CIM Why do 2h and OThere are several difference bond types in Chemistry. All are concerned with electrons. Intermolecular bonds occur between molecules (hydrogen bonding)

AlCl3 Aluminum Chloride WHAT TYPE Of BOND DO ALUMINUM AND CHLORINE FORM? Ionic: Metal and NonMetal Water sugar salt We are going to talk about bonding Bonding between atoms is CIM Why do 2h and OThere are several difference bond types in Chemistry. All are concerned with electrons. Intermolecular bonds occur between molecules (hydrogen bonding)

AlCl3 Aluminum Chloride COVALENT BOND WHAT TYPE Of BOND DO ALUMINUM AND CHLORINE FORM? Ionic: Metal and NonMetal COVALENT BOND Water sugar salt We are going to talk about bonding Bonding between atoms is CIM Why do 2h and OThere are several difference bond types in Chemistry. All are concerned with electrons. Intermolecular bonds occur between molecules (hydrogen bonding)

Confused? To muddy waters even further, there is no such thing as a purely ionic or covalent bond. AlCl3 Water sugar salt We are going to talk about bonding Bonding between atoms is CIM Why do 2h and OThere are several difference bond types in Chemistry. All are concerned with electrons. Intermolecular bonds occur between molecules (hydrogen bonding)

Electronegativity - +11 A measure of an atom or group of atom’s tendency to attract electrons Water sugar salt We are going to talk about bonding Bonding between atoms is CIM Why do 2h and OThere are several difference bond types in Chemistry. All are concerned with electrons. Intermolecular bonds occur between molecules (hydrogen bonding)

As you go down a group Electronegativity decreases. Additional Electron shielding and increased distance from the nucleus makes adding a new electron more difficult Increasing nuclear charge (pull) without any additional shielding makes makes adding an electron easier. Water sugar salt We are going to talk about bonding Bonding between atoms is CIM Why do 2h and OThere are several difference bond types in Chemistry. All are concerned with electrons. Intermolecular bonds occur between molecules (hydrogen bonding) As you go across a period Electronegativity increases.

Electronegativity (χ) is a “rule of thumb” Bond type is ∝ to Δχ

Δ Electronegativity ELECTRON TUG OF WAR!

Electron Tug of War H-H Hydrogen 2.20 H-F Fluorine 3.98

Electronegativity Sliding Bond Scale Δχ Bond Type Example 0.0-0.5 Non-Polar Covalent H2 ≥0.5 to >1 Polar Covalent HCl ≥1 to <2 Very Polar Covalent HF ≥2 Ionic Bond Na+Cl- Electronegativity Sliding Bond Scale Electron Tug of War NaCl H2O CO2

Water is a Polar Molecule! H2O Oxygen 3.44 Hydrogen 2.20 Drops on a Penny Snapping Drops Surface Tension Sand vs Snowman Capillary Action Melting Points Boiling Points Solubility

Carbon Dioxide is Non-Polar CO2 Oxygen 3.44 Carbon 2.55 Δχ=0.89 O C O Why is Carbon dioxide non-polar?

Carbon Dioxide is Non-Polar CO2 Oxygen 3.44 Carbon 2.55 Δχ=0.89 δ- δ+ δ- O C O Why is Carbon dioxide non-polar? Because it is linear or perfectly symmetrical.

Carbon Dioxide is Non-Polar CO2 Oxygen 3.44 Carbon 2.55 Δχ=0.89 δ- δ+ δ- O C O Why is Carbon dioxide non-polar? Because it is linear or perfectly symmetrical.

O H H Water is Bent δ- δ+ δ+ Because water is not a linear molecule. Why is Water Polar? δ+ δ+ Because water is not a linear molecule.

MOLECULAR GEOMETRY: VSEPR δ- O H H Why is Water Polar? δ+ δ+ Because water is not a linear molecule.

H C N What about HCN? δ+ δ- CO2 Hydrogen 2.20 Carbon 2.55 Nitrogen δ+ δ- H C N Prussic Acid Hydrogen Cyanide Prussic Acid is Polar Because it is linear but the ends have opposite charges.

Two types of Covalent Bonds Non-Polar Covalent Polar-Covalent Electrons Shared Equally: --all diatomic molecules Electrons Shared Unequally --due to electronegativity δ Small Delta indicates PARTIAL CHARGES There is a small degree of sharing and orbital overlap even in ionic bonds.

Ionic Bond (Extremely Polar) Practice Problems What type of bond will form between the following atoms? N and H F and F Ca and Cl Al and Cl H and Br K and Cl C and O Cl and F Li and O H and O Δ Electronegativity Bond Type 0.0-0.5 Non-Polar Covalent ≥0.5 to >1 Polar Covalent ≥1 to <2 Very Polar Covalent ≥2 Ionic Bond (Extremely Polar)

Practice Problems H—CL H—Br H—S H—C Answer: C and D tie to B to A What type of bond will form between the following atoms? Place these covalent bonds in order of least to most polar. N (3) and H (2.1) = 0.9 mod PC F (4) and F(4) = 0 = non-polar Ca (1) and Cl (3) = 2 = Ionic Al (1.5) and Cl (3) = 1.5 = very PC H and Br mod PC K and Cl ionic C and O mod to very PC Cl and F mod to very PC Li and O ionic H and O polar (thisH20!) H—CL H—Br H—S H—C Answer: C and D tie to B to A