Unit 3 A.7-A.9

Intermolecular forces are a force of attraction and repulsion between molecules. In the fractioning tower, molecules in the bottoms with more carbon atoms do not vaporize. Ball-and-stick models is a molecular model where each ball represents an atoms and each stick represents a pair of shared electrons connecting two atoms. Another molecular model is called a space-filling model which shows atoms in contact with each other. Alkanes are a hydrocarbon containing only a single covalent bond. When assembling a 3-D model of a methane molecule, the 3-D shape is called a tetrahedron, a regular triangular pyramid where the four bonds of each carbon atom in an alkane point to the corners of a tetrahedron. A molecular formula is a chemical expression indicating the number of each atom type within a molecule. Condensed formulas are more useful than molecular formulas and they are a chemical formula that provides additional information about bonding.