Ch 100: Fundamentals for ChemistryChemical Symbols & FormulasThe Periodic TableThe Periodic Table of ElementsElements and the Periodic TableDmitri Mendeleev (1834-1907)Ch 100: Fundamentals for ChemistryChapter 3: Elements & CompoundsLecture NotesChemical Symbols & Formulas•Each element has a unique chemical symbol•Examples of chemical symbols:–Hydrogen: H–Oxygen: O–Aluminum: Al•Each molecule has a unique chemical formula•The chemical formula of a molecule indicates1. the chemical symbol for each of the elements present2. The # of atoms of each element present in the moleculeExamples of chemical formulas:–Elemental oxygen: O2 (2 O atoms per molecule)–Water: H2O (2 H atoms & 1 O atom)–Aluminum sulfate: Al2(SO4)3 (2 Al, 3 S & 12 O atoms)The Periodic Table1. All of the known elements are arranged in a chart called the Periodic Table2. Each element in the Periodic Table is identified by both its chemical symbol and its Atomic Number–The elements are organized left-to-right and top-to-bottom according to their Atomic Number–The elements are arranged by similarity of chemical properties3. The columns are called Groups–Elements of each group typically have similar properties4. The rows are called Periods, and reflect the periodicity of chemical properties as atomic number increasesThe Periodic Table of ElementsElements and the Periodic TableThe elements can be categorized as: 1. Metals•The leftmost elements in the periodic table•Roughly 70% of all of the elements are metals2. Nonmetals•The rightmost elements of the periodic table3. Semimetals (metalloids)•The elements that reside along the “stair step” between the metals and nonmetals in the Periodic Table•The properties of semimetals are not quite metallic or non-metallic, but rather somewhere in betweenDmitri Mendeleev (1834-1907)•Russian born chemist•Considered one of the greatest science teachers of his era•He organized the known elements of his time into the first “periodic table”–Elements were organized by chemical properties (& by weight) -> called periodic properties–Surprisingly, his periodic table predicted the existence of 3 new elements (which were subsequently
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