CHM 101 1st Edition Lecture 3Overview of Last Lecture - Atomic Theory- Atomic Structure - Isotopes Lecture 3 OverviewI. Molecular compoundsII. Ions and Ionic CompoundsIII. Naming Ionic CompoundsIV. StoichiometryMolecular Compounds- Chemical combination of 2 or more nonmetalso Share electrons - Diatomic molecules o H2, N2, O2, F2, Cl2, Br2, I2 Chemical formulas are used to indicate the makeup of a compound - Molecular formula- indicates the number and the type of each element in a mmolculeIons and Ionic Compounds- Ions and ionic compounds form from the transfer of electrons between metals and nonmetals - Metals lose electrons to form positive ions called cations- Nonmetals gain electrons to form negative ions called anions - The magnitude of charge on an ion tells you how many electrons were lost to form a cation, or gained to for an anion Column Charge Example1A +1 K+2A +2 Mg2+These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.3A +3 Al3+5A -3 N3-6A -2 S2-7A -1 F-- Noble gases, 8A, do not usually form ions- Transition metals may form cations with more than onc chargeo Example: Iron has two cations Fe2+ and Fe3+- Ionic compounds exist as crystals composed of an array of cations and anions (usually not discrete ions)- Ionic compounds are neutral o The positive and negative charges in the formula unit must cancel outK and I K+ and I- KIAl and O Al3+ O2- Al2O3Naming Binary Ionic CompoundsI. Metal (cation) is named first and is the same as the element. The name of the nonmetal (anion) is changed to end in –idea. NaCl – sodium chlorideII. Prefixes are not used to indicate the number of the ions in the formulaa. CaCl2 – calcium chlorideIII. Transition metal cations can have more than one chargea. Use roman numeralsi. FeCl2 – Iron (II) Chlorideii. FeCl3 – Iron (III) ChlorideStoichiometry- Study of the quantitative aspects of chemical formulas and reactionso Chemical formulas tell us what a substance is and stoichiometry tells us how much- Chemical equation-expression of the identities and quantities of substances involved in a chemical or physical changeo Reactants  productso Chemical equations must be balanced  Matter is not created or destroyed Atoms are not created or destroyed in chemical reactionso Use coefficients to balance 2 H2 + O2  2