Chemical Formulas • A statement in chemical symbols that represents the composition of a substance • Ex: • NaOH sodium hydroxide • Li2O lithium oxide
What does it tell? • The element that makes up the compound • Shows the ratio of atoms in elements that combine to form a compound • Ex: • H2O
Empirical Formula • Represents the simplest ratio in which atoms combine to form a compound • EX: CH for the molecular formula C6H6
Molecular Formula • Show the numbers and kinds of atoms present in the molecule of a compound • EX: CO2 • 1 Carbon atom • 2 Oxygen atoms
Empirical, Molecular or Both • C2H2 Molecular • C6H6 Molecular • H2O Empirical & Molecular
Formula Units • The lowest whole number ratio of ions in an ionic compound. Ionic formula doesn’t represent molecules • NaCl
9.1 Monatomic Ions • Monatomic Ions • How are the charges of Group A metal and nonmetal ions related to their positions in the periodic table?
9.1 Monatomic Ions • Monatomic ions consist of a single atom with a positive or negative charge resulting from the loss or gain of one or more valence electrons, respectively. • The number of electrons is no longer equal to the number of protons, therefore the atom becomes an ion • Ions are atoms or groups of atoms that have a positive or negative charge
9.1 Monatomic Ions • Cations • When the metals in Groups 1A, 2A, and 3A lose electrons, they form cations with positive charges equal to their group number. • The names of the cations of the Group 1A, Group 2A, and Group 3A(13) metals are the same as the name of the metal, followed by the word ion or cation.
9.1 Monatomic Ions • These elements have ionic charges that can be obtained from their group numbers.
9.1 Monatomic Ions • Anions • Atoms or groups of atoms with a negative charge • Anion names start with the stem of the element name and end in -ide. • Cl becomes Cl- • Chloride ion
9.1 Monatomic Ions • These Group A elements form anions.
9.1 Monatomic Ions
9.1 Monatomic Ions • The charges of the cations of many transition metal ions must be determined from the number of electrons lost.
9.1 Monatomic Ions • These colorful solutions contain the transition metal ions Co3+, Cr3+, Fe3+, Ni2+, and Mn2+.
9.1 Monatomic Ions • Many transition metal compounds are colored and can be used as pigments.
9.1 Monatomic Ions • Two methods are used to name the ions of transition metals. • The Stock system • The classical method
9.1 Monatomic Ions • In the Stock system, a Roman numeral in parentheses is placed after the name of the element to indicate the numerical value of the charge.
9.1 Monatomic Ions • In an older less, useful method, the classical name of the element is used to form the root name for the element.
9.1 Monatomic Ions
9.1 Polyatomic Ions • These models show the structures of four common polyatomic ions.
9.1 Polyatomic Ions • Some ions, called polyatomic ions, are composed of more than one atom. • The names of most polyatomic anions end in -ite or -ate.
9.1 Polyatomic Ions • Names and Formulas of Some Common Polyatomic Ions
9.1 Polyatomic Ions • Sodium hydrogen carbonate can relieve an upset stomach.
9.1 Polyatomic Ions • HCO3–, HPO42–, and H2PO4– ions in your blood are critical for your health.
9.1 Polyatomic Ions • Fertilizers contain HPO42– and H2PO4– ions.
Section Quiz. • 1. When metals from groups 1A, 2A, and 3A form cations, the charge on the ion is equal to • 8 minus the group number. • the group number minus 8. • the period number. • the group number.
2. Which of the following are positively charged polyatomic ions? • (I) ammonium ion • (II) perchlorate ion • (III) ferric ion • I only • II only • III only • I and III
9.1 Section Quiz • 3. If the name of an ion ends in -ite or -ate, the ion is a a. polyatomic cation. b. polyatomic anion. c. transition metal cation. d. monatomic anion.
9.2 Binary Ionic Compounds • Binary Ionic Compounds • How are the names of binary ionic compounds determined? • How do you write the formulas for binary ionic compounds?
9.2 Binary Ionic Compounds • Naming Binary Ionic Compounds • A binary compound is composed of two elements and can be either ionic or molecular. • To name any binary ionic compound, place the cation name first, followed by the anion name. • Consist of a metal and non-metal
9.2 Binary Ionic Compounds • Tin(II) sulfide, or SnF2,is added to toothpastes to prevent cavities.
9.2 Binary Ionic Compounds • Tin(IV) sulfide, or SnS2, is used in glazes for porcelain fixtures and dishes.
9.2 Binary Ionic Compounds • Hematite, a common ore of iron, contains iron (III) oxide. The balanced formula is Fe2O3.
9.2 Binary Ionic Compounds • Writing Formulas for Binary Ionic Compounds • Write the symbol of the cation and then the anion. • Add whatever subscripts are needed to balance the charges + and – charges must cancel out • Less electronegative element goes first
Simulation 9 • Simulation 9 Simulate combining ions and deriving the chemical formulas for several ionic compounds.
9.2 Conceptual Problem 9.2
9.2 Conceptual Problem
A) NaI • B) SnCl2 • C) K2S • D) CaI2
9.2 Compounds With Polyatomic Ions • Compounds with Polyatomic Ions • How do you write the formulas and names of compounds containing polyatomic ions?
Compounds With Polyatomic Ions 9.2 • Compound made up of three elements Cation (metal) Anion (polyatomic) • Write the symbol for the cation followed by the formula for the polyatomic ion and balance the charges. • The formula for polyatomic ion is placed in parenthesis • The subscript is placed outside the parenthesis
9.2 Compounds With Polyatomic Ions • Oysters produce calcium carbonate to form their shells and sometimes pearls.
9.2 Compounds With Polyatomic Ions • Lead(II)sulfate is an important component of an automobile battery.
9.3 Conceptual Problem 9.3