Rp > 1 disease is to spread

Rp = 1 disease is constant

Rp < 1, disease dies out

#Id: 7755

#Unit 1. Molecules and their Interaction Relevant to Biology

Electronegativity is a measure of the tendency of an atom to attract a bonding pair of electrons. The Pauling scale is the most commonly used.

#Id: 7756

#Unit 1. Molecules and their Interaction Relevant to Biology

Fluorine (the most electronegative element) is assigned a value of 4.0, and values range down to cesium and francium which are the least electronegative at 0.7

#Id: 7757

#Unit 1. Molecules and their Interaction Relevant to Biology

Molecules are groups of atoms that behave as a single unit.

#Id: 7758

#Unit 1. Molecules and their Interaction Relevant to Biology

A molecule is the smallest part of a substance that has the physical and chemical properties of that substance. In some respects, a molecule is similar to an atom. A molecule, however, is composed of more than one atom.

#Id: 7759

#Unit 1. Molecules and their Interaction Relevant to Biology

Some elements exist naturally as molecules. For example, hydrogen and oxygen exist as two-atom molecules.

#Id: 7760

#Unit 1. Molecules and their Interaction Relevant to Biology

Sulfur normally exists as an eight-atom molecule, S8, while phosphorus exists as a four-atom molecule, P4