Chapter 4 Compounds and Their Bonds 4.4 Polyatomic Ions 1

A polyatomic ion is a group of atoms. has an overall ionic charge. Some examples of polyatomic ions are NH 4 + ammoniumOH − hydroxide NO 3 − nitrateNO 2 − nitrite CO 3 2− carbonatePO 4 3− phosphate HCO 3 − hydrogen carbonate (bicarbonate) 2

Some Compounds with Polyatomic Ions 3

Some Names of Polyatomic Ions The names of common polyatomic anions end in ate. NO 3 − nitratePO 4 3− phosphate with one oxygen less end in ite. NO 2 − nitritePO 3 3− phosphite with hydrogen attached use the prefix hydrogen (or bi). HCO 3 − hydrogen carbonate(bicarbonate) HSO 3 − hydrogen sulfite (bisulfite) 4

Names and Formulas of Common Polyatomic Ions 5 Memorize these ions

Naming Compounds with Polyatomic Ions The positive ion is named first, followed by the name of the polyatomic ion. NaNO 3 sodium nitrate K 2 SO 4 potassium sulfate Fe(HCO 3 ) 3 iron(III) bicarbonate or iron(III) hydrogen carbonate (NH 4 ) 3 PO 3 ammonium phosphite 6

Guide to Naming Compounds with Polyatomic Ions 7

Some Compounds with Polyatomic Ions 8

Examples Match each formula with the correct name. A. MgS1) magnesium sulfite MgSO 3 2) magnesium sulfate MgSO 4 3) magnesium sulfide B. Ca(ClO 3 ) 2 1) calcium chlorate CaCl 2 2) calcium chlorite Ca(ClO 2 ) 2 3) calcium chloride 9

Examples Name each of the following compounds: A.Mg(NO 3 ) 2 B.Cu(ClO 3 ) 2 C.PbO 2 D.Fe 2 (SO 4 ) 3 E.Ba 3 (PO 3 ) 2 10

Writing Formulas with Polyatomic Ions The formula of an ionic compound containing a polyatomic ion must have a charge balance that equals zero (0). Na + and NO 3 − -> NaNO 3 with two or more polyatomic ions has the polyatomic ions in parentheses. Mg 2+ and 2NO 3 − -> Mg(NO 3 ) 2 subscript 2 for charge balance 11

Examples Select the correct formula for each. A. aluminum nitrate 1) AlNO 3 2) Al(NO) 3 3) Al(NO 3 ) 3 B. copper(II) nitrate 1) CuNO 3 2) Cu(NO 3 ) 2 3) Cu 2 (NO 3 ) C. iron(III) hydroxide 1) FeOH2) Fe 3 OH3) Fe(OH) 3 D. tin(IV) hydroxide 1) Sn(OH) 4 2) Sn(OH) 2 3) Sn 4 (OH) 12

Examples Write the correct formula for each. A.potassium bromate B.calcium carbonate C.sodium phosphate D.iron(II) nitrite 13

Flowchart for Naming Ionic Compounds 14

Examples Name the following compounds: A. Ca 3 (PO 4 ) 2 B. FeBr 3 C. Al 2 S 3 D. NaHCO 3 15

Examples Write the formulas for the following: A. iron(II) hydroxide B. aluminum carbonate C. copper(II) bromide D. lithium phosphate 16

Chapter 4 Compounds and Their Bonds 4.5 Covalent Compounds 17 Copyright © 2009 by Pearson Education, Inc.

Covalent Bonds Covalent bonds form when atoms share electrons to complete octets. between two nonmetal atoms. between nonmetal atoms from Groups 4A (14), 5A (15), 6A (16), and 7A (17). 18

Hydrogen Molecule A hydrogen molecule is stable with 2 electrons (helium). has a shared pair of electrons. 19

Forming Octets in Molecules In a fluorine, F 2,, molecule, each F atom shares 1 electron. attains an octet. 20

Carbon Forms 4 Covalent Bonds In a CH 4 (methane) molecule, 1 C atom shares electrons with 4 H atoms to attain an octet. each H atom shares 1 electron to become stable, like helium. 21

Multiple Bonds In a nitrogen molecule, N 2, each N atom shares 3 electrons. each N attains an octet. the bond is a multiple bond called a triple bond. the name is the same as the element. 22

Naming Covalent Compounds In the names of covalent compounds, prefixes are used to indicate the number of atoms (subscript) of each element. (mono is usually omitted) 23

Guide to Naming Covalent Compounds 24

Naming Covalent Compounds What is the name of SO 3 ? 1. The first nonmetal is S sulfur. 2. The second nonmetal is O, named oxide. 3. The subscript 3 of O is shown as the prefix tri. SO 3 -> sulfur trioxide The subscript 1 (for S) or mono is understood. 25

Naming Covalent Compounds Name P 4 S The first nonmetal, P, is phosphorus. 2. The second nonmetal, S, is sulfide. 3. The subscript 4 of P is shown as tetra. The subscript 3 of O is shown as tri. P 4 S 3 -> tetraphosphorus trisulfide 26

Formulas and Names of Some Covalent Compounds 27

Examples Select the correct name for each compound. A.SiCl 4 1) silicon chloride 2) tetrasilicon chloride 3) silicon tetrachloride B. P 2 O 5 1) phosphorus oxide 2) phosphorus pentoxide 3) diphosphorus pentoxide C.Cl 2 O 7 1) dichlorine heptoxide 2) dichlorine oxide 3) chlorine heptoxide 28

Examples Write the name of each covalent compound. CO_____________________ CO 2 _____________________ PCl 3 _____________________ CCl 4 _____________________ N 2 O_____________________ 29

Guide to Writing Formulas for Covalent Compounds 30

Example: Writing Formulas for Covalent Compounds Write the formula for carbon disulfide. STEP 1: Elements are C and S STEP 2: No prefix for carbon means 1 C Prefix di = 2 Formula: CS 2 31

Examples Write the correct formula for each of the following: A. phosphorus pentachloride B. dinitrogen trioxide C. sulfur hexafluoride 32

Examples Identify each compound as ionic or covalent, and give its correct name. A. SO 3 B. BaCl 2 C. (NH 4 ) 3 PO 3 D. Cu 2 CO 3 E. N 2 O 4 33

Examples Determine if each is ionic (I) or covalent (C ), and write the formula. A. calcium nitrate B. boron trifluoride C. aluminum carbonate D. dinitrogen tetroxide E. copper(I) phosphate 34

Examples Identify each compound as ionic or covalent and give its correct name. A. Ca 3 (PO 4 ) 2 B. FeBr 3 C. SCl 2 D. Cl 2 O E. N 2 35