This chapter contains an ordinance defining, regulating and restricting the location, use, height, number of stories and size of buildings and other structures; the size of yards and other open spaces; the density of population; the location and use of buildings, structures and land for trade, industry and other purposes; all designed for one or more of the following purposes: to promote the public health, safety and welfare; to protect persons and property from fire, flood and other disaster; to provide adequate light, air and open space; to establish proper population densities; to preserve the environment; to protect valuable natural resources; to prevent neighborhood decay; to prevent urban or suburban sprawl; and to provide for the objectives as required by law.