应用化学专业英语 教学课件 ppt 作者 黄忠 谢普会 付颖 主编Lesson 2 nomenclature of inorganic compounds 3课件.ppt

Lesson 2 Nomenclature of Inorganic CompoundsWriting Formulas Systematic Naming There are too many compounds to remember the names of them all. Compound is made of two or more elements. Put together atoms. Name should tell us how many and what type of atoms. Periodic Table More than a list of elements. Put in columns because of similar properties. Each column is called a group. Representative elements The group A elements Metals Metals Luster – shiny. Ductile – drawn into wires. Malleable – hammered into sheets. Conductors of heat and electricity. Transition metals The Group B elements Non-metals Dull Brittle Nonconductors- insulators Metalloids or Semimetals Properties of both Semiconductors Atoms and ions Atoms are electrically neutral. Same number of protons and electrons. Ions are atoms, or groups of atoms, with a charge. Different numbers of protons and electrons. Only electrons can move. Gain or lose electrons. Anion A negative ion. Has gained electrons. Non metals can gain electrons. Charge is written as a super script on the right. Compounds Follow the Law of Definite Proportion. Have a constant composition. Have to add the same number of atoms every time. Two types. Two Types of Compounds Molecular compounds Made of molecules. Made by joining nonmetal atoms together into molecules. Two Types of Compounds Ionic Compounds Made of cations and anions. Metals and nonmetals. The electrons lost by the cation are gained by the anion. The cation and anions surround each other. Smallest piece is a FORMULA UNIT. Two Types of Compounds Chemical Formulas Shows the kind and number of atoms in the smallest piece of a substance. Molecular formula- number and kinds of atoms in a molecule. CO2 C6H12O6 Formula Unit The smallest whole number ratio of atoms in an ionic compound. Ions surround each other so you can’t say which is hooked to which. Charges on ions For most of the Group A elements, the Periodic Table can tell what kind of ion they will form from their location.