Notes – Chapter Two Atoms, Molecules, and Ions

Section 2.2 Fundamental Chemical Laws  Law of conservation of Mass  Law of Definite Proportions  Law of Multiple Proportions

Section 2.3 Dalton’s Atomic Theory  Each element is made up of tiny particles called atoms  The atoms of a given element are identical; the atoms of different elements are different in some fundamental way or ways  Chemical compounds are formed when atoms of different elements combine with each other. A given compound always has the same relative numbers and types of atoms  Chemical reactions involved reorganization of the atoms – changes in the way they are bound together. The atoms themselves are not changed in a chemical reaction.

Section 2.3 Dalton’s Atomic Theory – Slide 2 Avogadro’s hypothesis - At the same temperature and pressure, equal volumes of different gases contain the same number of particles. Under the above conditions, the volume of a gas is determined by the number of molecules present, not by the size of the individual particles.

Section 2.4 Early Experiments to Characterize the Atom  The Electron  Cathode-ray tubes  J.J. Thomson  Robert Millikan  Radioactivity  The Nuclear Atom  Ernest Rutherford

Section 2.5 The Modern View of Atomic Structure  Protons  Neutrons  Isotopes  Atomic Number  Mass Number  Writing symbols for atoms

Section 2.6 Molecules and Ions  Chemical Bonds  Covalent bonds  Molecules  Chemical formula  Structural formula  Space-filling model  Ball-and-stick models  Ionic bonds  Ions  Cation  Anion  Ionic bonding  Ionic solid or salt  Polyatomic ions

Section 2.7 An Introduction to the Periodic Table  Periodic table  Metals  Nonmetals  Groups (families)  Alkali metals  Alkaline earth metals  Halogens  Noble gases  Periods

Section 2.8 Naming Simple Compounds  Binary compounds  Type 1  Type 2  Ionic compounds with Polyatomic ions  Type 3  Formulas with Names  Acids

Binary Ionic Compounds Type 1 1.The cation is always named first and the anion second. 2.A monatomic cation takes its name from the name of the element. 3.A monatomic anion is named by taking the root of the element named and adding - ide.

Binary Ionic Compounds – Type 2  These compounds follow the same rules as Type 1 with the exception that the cation is a metal with multiple charges.  The charges of the cation must be written in the formula using a Roman numeral. Example, Fe +2 is represented as Iron (II).  For cations that come from the transition metal section with only one charge do not use roman numerals.

Ionic Compounds with Polyatomic Ions  Polyatomic ions may be either cations or anions depending on their charge.  Polyatomic ions state their name when in compounds. For compounds that contain two polyatomic ions, both names are stated without an ending added.  Oxyanions – anions combined with the same element and different numbers of oxygen atoms.

Binary Covalent Compounds – Type 3  Compounds formed from two nonmetals.  Naming these compounds 1.The first element in the formula is named first, using the full element name. 2.The second element is named as if it were an anion. 3.Prefixes are used to denote the numbers of atoms present. 4.The Prefix mono- is never used for naming the first element. Prefixes Used to Indicate Number in Chemical Names PrefixNumber Indicated Mono1 Di2 Tri3 Tetra4 Penta5 Hexa6 Hepta7 Octa8 Nona9 Deca10

Formulas From Names  When given the name of a compound complete the following steps in order to write the formula correctly. 1.Identify if the compound is covalent or ionic. 2.If ionic, identify the charges for both elements. Use subscripts to balance the charges of the cation and anion. 3.If covalent, write the compound using prefixes. If a prefix is attached, that prefix is the subscript for that element.

Acids Does the anion contain oxygen? NoYes Hydro – + anion root + - ic Hydro(anion root)ic acid Check the ending of the anion -ite -ate Anion or element root + -ous (root)ous acid Anion or element root + - ic (root)ic acid

Oxyanionic Acids  The names of oxyanionic acids are based on the amount of oxygen atoms in each compound. (See chart on page 72)  Example of an oxyanioic acid with four different amounts of oxygen. Acid AnionName of Acid  HClO 4 Perchlorate Perchloric acid  HClO 3 ChlorateChloric acid  HClO 2 ChoriteChlorous acid  HClOHypochloriteHypochlorous acid