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Regents Chemistry Review By Topic: Chemical Bonding And Intermolecular Forces

Ionic Bond = electrons are transferred

Covalent Bond = electrons are shared

Single covalent bond contains 2 electrons. Double contains 2*2 = 4 electrons. A triple bond contains 3*2=6 electrons.

There are two types of covalent bonds: nonpolar and polar. Hint: Nonpolar bonds are usually between two atoms of the same element (H2, Cl2...)


Table S shows electronegativity values of elements. The difference in electronegativity values between the two elements determine how polar the bond is. The most polar bond results from the biggest electronegativity difference. For example, Fluorine = 4.0 and Hydrogen = 2.2. 4.0-2.2 = 1.8 is the electronegativity difference for HF.


Metals have metallic bonding. Metals are located to the left of the staircase on the Periodic Table. In metallic bonding, there is a "sea" of mobile electrons around positive ions.


Intermolecular Forces

Intermolecular forces are forces of attraction between molecules.

Types of intermolecular forces:

Hydrogen bonding = exists between molecules that have OH, NH or FH bonds. For example: NH3, H2O. These are strong intermolecular forces.

Dipole-dipole = exists between polar molecules. A polar molecule is asymmetrical. Example of polar molecules: NH3, HBr.

London Dispersion forces = theses intermolecular forces are present between all molecules. However, these are the only intermolecular forces between nonpolar molecules. Nonpolar molecules are symmetrical. Dispersion forces are the weakest intermolecular forces.


Intermolecular forces and properties:

Stronger intermolecular forces result in higher boiling point and lower vapor pressure.


Table H shows the vapor pressure of different molecules under different temperature.


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