explain the emergence of modern theories based on historical development. For example, students should be able to explain the origin of the atomic theory beginning with the Greek atomists and continuing through the most modern quantum models. Standard CH.2 CH.2 The student will investigate and understand that the placement of elements on the periodic table is a function of their atomic structure. The periodic table is a tool used for the investigations of average atomic mass, mass number, and atomic number; isotopes, half lives, and radioactive decay; mass and charge characteristics of subatomic particles; families or groups; periods; trends including atomic radii, electronegativity, shielding effect, and ionization energy; electron configurations, valence electrons, and oxidation numbers; chemical and physical properties; and historical and quantum models. Essential Understandings The concepts developed in this standard include the following: The periodic table is arranged in order of increasing atomic numbers. The atomic number of an element is the same as the number of protons. In a neutral atom, the number of electrons is the same as the number of protons. All atoms of an element have the same number of protons. The average atomic mass for each element is the weighted average of that element’s naturally occurring isotopes. The mass number of an element is the sum of the number of protons and neutrons. It is different for each element’s isotopes. An isotope is an atom that has the same number of protons as another atom of the same element but has a different number of neutrons. Some isotopes are radioactive; many are not. Half-life is the length of time required for half of a given sample of a radioactive isotope to decay. Electrons have little mass and a negative (–) charge. They are located in electron clouds or probability clouds outside the nucleus.
Carbon-based compounds include simple hydrocarbons, small carbon-containing molecules with functional groups, complex polymers, and biological molecules. Petrochemicals contain hydrocarbons, including propane, butane, and octane. There is a close relationship between the properties and structure of organic molecules. Common pharmaceuticals that are organic compounds include aspirin, vitamins, and insulin. Small molecules link to make large molecules called polymers that have combinations with repetitive subunits. Natural polymers include proteins and nucleic acids. Human-made (synthetic) polymers include polythene, nylon and Kevlar. Essential Knowledge and Skills In order to meet this standard, it is expected that students will describe how saturation affects shape and reactivity of carbon compounds. draw Lewis dot structures, identify geometries, and describe polarities of the following molecules: CH4, C2H6, C2H4, C2H2, CH3CH2OH, CH2O, C6H6, CH3COOH. recognize that organic compounds play a role in natural and synthetic pharmaceuticals. recognize that nucleic acids and proteins are important natural polymers. recognize that plastics formed from petrochemicals are organic compounds that consist of long chains of carbons. conduct a lab that exemplifies the versatility and importance of organic compounds (e.g., aspirin, an ester, a polymer).