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Covalent Bonding. Polar Bonds and Molecules. Covalent Bonding -- Polar Bonds and Molecules --. Bond Polarity “The Tug of War” The pairs of electrons that are bonds between atoms are pulled between the nuclei of the atoms in a bond. The electronegativities of the atoms determine the winner.
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Covalent Bonding Polar Bonds and Molecules
Covalent Bonding-- Polar Bonds and Molecules -- Bond Polarity • “The Tug of War” • The pairs of electrons that are bonds between atoms are pulled between the nuclei of the atoms in a bond. • The electronegativities of the atoms determine the winner. • Classifications for Bonds • Nonpolar covalent • When atoms pull the bond equally • Happens with two atoms of equal electronegativity, most often using the same atoms • Examples: H2, O2, N2 • Polar covalent • When atoms pull the bond unequally • Happens with two atoms of different electronegativities • Example: HCl, HF, NH
Covalent Bonding-- Polar Bonds and Molecules -- Bond Polarity • In a polar molecule, one end of the molecule is slightly more electronegative than the other atom, resulting in one atom being slightly negative (-) because of higher electronegativitiy, and the other atom being slightly positive (+) because of lower electronegativity. • is known as a partial charge since it is much less than 1+ or 1- charge.
Covalent Bonding-- Polar Bonds and Molecules -- Bond Polarity • Electronegativities and Bond Types • H: 2.1 Cl: 3.0 Since hydrogen is less, it will have the positive partial charge while chlorine has the negative partial charge. • 3.0 – 2.1 = 0.9 HCl is polar covalent.
Covalent Bonding-- Polar Bonds and Molecules -- Polar Molecules • Dipole • Molecule that has two poles • Example: HCl from the previous page • Polar vs. Nonpolar • H2O and CO2 • Both have 3 atoms; yet, • One is polar and one is nonpolar. • Why? • Structure (with bond polarity) determines the molecules polarity.
