Chapter 6 Ionic Compounds Silence cell phones and pagers. Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

Octet Rule An octet Contains 8 valence electrons. Is associated with the stability of the noble gases. Exception is He that is stable with 2 valence electrons (duet). valence electrons He 2 2 (Exception) Ne 2, 8 8 Ar 2, 8, 8 8 Kr 2, 8, 18, 8 8

Review: Valence Electrons The valence electrons Are the electrons in the s and p sublevels in the highest energy level. Are related to the Group number of the element. Determine the chemical properties of the elements. Elements with similar properties have the same number of ___________________ !

Forming Octets Atoms acquire octets By losing, gaining, or sharing valence electrons. To form compounds. To become more stable.

Size of Sodium Ion The sodium ion Na+ Forms when the Na atom loses one electron from the 3rd energy level, its valence electron. Is smaller than a Na atom. Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings Octet

Size of Fluoride Ion The fluoride ion F- Forms when a valence electron is added. Has increased repulsions due to the added valence electron. Is larger than F atom Octet Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

Ionic and Covalent Bonds Ionic bonds involve Loss of electrons by a metal. Gain of electrons by a nonmetal. Covalent bonds involve A sharing of electrons. Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

Metals Form Positive Ions Octets by losing all of their valence electrons. Positive ions with the electron configuration of the nearest noble gas. Positive ions with fewer electrons than protons. Group 1A(1) metals  ion 1+ Group 2A(2) metals  ion 2+ Group 3A(13) metals  ion 3+ Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

Formation of a Sodium Ion, Na+ Sodium achieves an octet by losing its one valence electron. 2, 8, 1 2, 8 Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

Charge of Sodium Ion, Na+ With the loss of its valence electron, the sodium ion has a 1+ charge. Sodium atom Sodium ion 11p+ 11p+ 11e- 10e- 0 1+ 2, 8 Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

Formation of Mg2+ Magnesium achieves an octet by losing its two valence electrons. 2, 8, 2 2, 8 Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

Charge of Magnesium Ion Mg2+ With the loss of two valence electrons, magnesium forms a positive ion with a 2+ charge. Mg atom Mg2+ ion 12p+ 12p+ 12e- 10e- 0 2+ 2, 8 Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

Formation of Negative Ions In ionic compounds, nonmetals Achieve an octet arrangement. Gain electrons. Form negatively charged ions with 3-, 2-, or 1- charges.

Formation of Chloride Ion, Cl- Chlorine achieves an octet by adding an electron to its valence electrons. 2, 8, 7 2, 8, 8 Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

Charge of a Chloride Ion, Cl- A chlorine ion forms When Cl gains one electron With a 1- charge. Chlorine atom Chloride ion 17p+ 17p+ 17e- 18e- 0 1– Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

Some Ionic Charges I- Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

Ionic Charge from Group Numbers The charge of a positive ion is equal to its Group number. Group 1A(1) = 1+ Group 2A(2) = 2+ Group 3A(13) = 3+ The charge of a negative ion is obtained by subtracting 8 or 18 from its Group number . Group 6A(16) = 6 - 8 = 2- or 16 - 18 = 2-

Upon loss or gain of electons, the electronic arrangement of the ion is “_____________” with its nearest noble gas.

Octet Rule - What is special about “8” ? An octet Is ___ valence electrons Is associated with the stability of the noble gases He is stable with ___ valence electrons (duet). valence electrons He 1s2 __ Ne 1s2 2s2 2p6 __ Ar 1s2 2s2 2p6 3s2 3p6 __ Kr 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 __

Learning Check Select the correct answer for Sodium 1A(1): 1. Number of ________________ A) ________ B) ________ C) ________ 2. Electron ________ to achieve ________ A) ________ B) ________ C) ________ 3. _____________ of sodium ion A) ________ B) ________ C) ________ 4. The ________ for the sodium ion

Learning Check Select the correct answer for nitrogen 5A(15): 5. Number of __________________ A) ________ B) ________ C) ________ Change in ________ for ________ A) ________ B) ________ C) ________ 7. Ionic ________ of ________ A) ________ B) ________ C) ________ 8. The ________ for the ________ A) ________ B) ________ C) ________

Compounds - Compounds result from the formation of chemical bonds between two or more different elements.

Chemical bond: attractive force holding two or more atoms together.

Ionic Bonds - electron transfer process Ionic Bonds - electron transfer process. Typically between a metal and a nonmetals Covalent Bonds - electrons shared. Typically involving nonmetals.

Ionic Compounds Ionic compounds Consist of positive and negative ions. Have ionic bonds between positively and negatively charged ions. Have high melting and boiling points. Are solid at room temperature.

Salt is An Ionic Compound Sodium chloride (table salt) is an example of an ionic compound. Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

Ionic Formulas An ionic formula Consists of positively and negatively charged ions. Is neutral. Has charge balance. total positive charge = total negative charge Uses subscripts to indicate the number of ions needed to give charge balance.

Ionic Formula of NaCl In an ionic formula The symbol of the metal is written first followed by the symbol of the nonmetal. The charges of the ions in the compound are not shown. Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

Charge Balance in NaF The formulas of ionic compounds are determined from the charges on the ions. atoms ions     – Na  +  F :  Na+ : F :  NaF     sodium fluorine sodium fluoride The overall charge of NaF is zero (0). Na+ F- = NaF (1+ ) + (1-) = 0

Charge Balance In MgCl2 In forming MgCl2 A Mg atom loses two valence electrons. Two Cl atoms each gain one electron. Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

Using Lewis Electron Dot Symbols Br Mg + →

Using Lewis Electron Dot Symbols Al + N →

Writing Ionic Formulas from Charges Charge balance is used to write the formula for sodium nitride, a compound containing Na+ and N3−. Na+ 3 Na+ + N3− = Na3N 3(+1) + 1(3-) = 0 Note: the subscript 3 for three sodium ions.

Formula from Ionic Charges Write the ionic formula of the compound with Ba2+ and Cl. Write the symbols of the ions. Ba2+ Cl Balance the charges. Ba2+ Cl two Cl- needed Cl Write the ionic formula using a subscript 2 for two chloride ions. BaCl2

Learning Check Write the correct formula for the ionic compounds formed by the following ions: 1. 2. 3.

Naming and Writing Ionic Formulas Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

Naming of Ionic Compounds In the name of an ionic compound The positive ion (first ion) is named as the element. The negative ion (second ion) is named by changing the end of the element name to –ide.

Names of Some Common Ions Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

Learning Check Complete the names of the following ions: Ba2+ Al3+ K+ _________ __________ _________ N3 O2 F _________ __________ _________ P3 S2 Cl _________ __________ _________

Naming Ionic Compounds with Two Elements To name a compound that contains two elements Identify the cation and anion. Name the positive metal ion (cation) as the element. Name the anion by changing the ending to ide. Name the cation first followed by the name of the anion.

Charges of Representative Elements Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

Some Ionic Compounds with Two Elements Formula Ions Name NaCl Na+ Cl- sodium chloride K2S K+ S2- potassium sulfide MgO Mg2+ O2- magnesium oxide CaI2 Ca2+ I- calcium iodide Al2O3 Al3+ O2- aluminum oxide

More Ionic Compounds Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

Write the formulas and names for compounds of the following ions: N3− Br− S2− Na+ Al3+

Write the names of the following compounds: 1) CaO ___________ 2) KBr ___________ 3) Al2O3 ___________ 4) MgCl2 ___________

Most Transition Metals form Two or More Positive Ions Most of the transition metals Form 2 or more positive ions. For example, Copper forms Cu+ and Cu2+ Iron forms Fe2+ and Fe3+ Gold form Au+ and Au3+

Metals that form more than One Cation Some Metals That Form More Than One Positive Ion Lead Pb2+ lead(II) Pb4+ lead(IV) Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

Periodic Table and Some Ions Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

Naming Variable Charge Metals Transition metals With two different ions use a Roman numeral after the name of the metal to indicate ionic charge. Only zinc, silver, and cadmium form one ion (Zn2+, Ag+, and Cd2+) Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

Naming FeCl2 To name FeCl2 [ 1 Iron ion + 2 chloride ions ] 1. Determine the charge of the cation using the charge of the anion (Cl-). Fe ion + 2 Cl- = 1(?) + 2(1-) = 0 Fe ion = 2+ Fe2+ 2. Name the cation by the element name and a Roman numeral in parenthesis to show charge. Fe2+ = iron(II) 3. Write the name of the anion with an ide ending. iron(II) chloride = FeCl2

Naming Cr2O3 To name Cr2O3 1. Determine the charge of cation from the anion (O2-). 2Cr ions + 3 O2- = ? + 3(2-) = ? - 6 = 0 ? = +6 +6/ 2Cr ions = +3 Cr ion = 3+ Cr3+ 2. Name the cation by the element name and use a Roman numeral in parenthesis to show its charge. Cr3+ = chromium(III) 3. Write the name of the anion with -ide ending. chromium(III) oxide = Cr2O3

Learning Check Select the correct name for each. 1. 2.

Writing Formulas Write the formula of potassium sulfide. STEP 1 Identify the cation and anion. potassium = K+ sulfide = S2− STEP 2. Balance the charges. K+ S2− K+ 2(1+) + 2(1-) = 0 STEP 3. 2 K+ and 1 S2− = K2S

Writing Formulas Write the formula of cobalt(III) chloride. STEP 1. Identify the cation and anion. cobalt(III) = Co3+ (III = charge of 3+) chloride = Cl− STEP 2. Balance the charges. Co3+ Cl− Cl− = (3+) + 3(1-) = 0 Cl− STEP 3. 1 Co3+ and 3 Cl− = CoCl3

Learning Check The correct formula for each of the following is: 1. 2.

Polyatomic Ions Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

Polyatomic Ions A polyatomic ion Is a group of atoms. Has an overall ionic charge. Some examples of polyatomic ions are NH4+ ammonium OH− hydroxide NO3− nitrate NO2− nitrite CO32− carbonate PO43− phosphate HCO3− hydrogen carbonate (bicarbonate)

Some Compounds with Polyatomic Ions Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

More Names of Polyatomic Ions The names of common polyatomic anions End in ate. NO3− nitrate PO43− phosphate With one oxygen less end in ite. NO2− nitrite PO33− phosphite With hydrogen attached use prefix hydrogen (or bi). HCO3− hydrogen carbonate (bicarbonate) HSO3− hydrogen sulfite (bisulfite)

Names and Formulas of Common Polyatomic Ions Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

Names and Formulas of Common Polyatomic Ions Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

Prefixes for Names of Polyatomic Ions of Halogens Polyatomic ions of the halogens require prefixes. ClO4− perchlorate one oxygen more ClO3− chlorate most common form ClO2− chlorite one oxygen less ClO− hypochlorite two oxygens less

Naming Compounds with Polyatomic Ions The positive ion is named first followed by the name of the polyatomic ion. NaNO3 sodium nitrate K2SO4 potassium sulfate Fe(HCO3)3 iron(III) bicarbonate or iron(III) hydrogen carbonate (NH4)3PO3 ammonium phosphite

Some Compounds with Polyatomic Ions Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

Naming Polyatomic Ions Nick the Camel Craved and ate a Clam Supper in Phoenix.

Learning Check Select the correct formula for each: 1. 2. 3. 4.

Learning Check Match each formula with the correct name: A) magnesium sulfite B) magnesium sulfate C) magnesium sulfide

Learning Check A) calcium chlorate B) calcium chlorite C) calcium hypochlorite

Learning Check Name each of the following compounds: 1. Mg(NO3)2 2. Cu(ClO3)2 3. PbO2 4. Fe2(SO4)3 5. Ba3(PO3)2

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 NO3− → NaNO3 With two or more polyatomic ions encloses the polyatomic ions in parentheses. Mg2+ and 2NO3− → Mg(NO3)2 subscript 2 for charge balance

Learning Check Write the correct formula for each: 1. potassium bromate 2. calcium carbonate 3. sodium phosphate 4. iron(III) oxide 5. iron(II) nitrite

Naming Ionic Compounds Review: Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

Flowchart for Naming Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

Learning Check Name the following compounds: A. Ca3(PO4)2 B. FeBr3 C. Al2S3 D. Mn(NO2)2 E. NaHCO3

Learning Check Write the formulas for the following: A. calcium nitrate B. iron(II) hydroxide C. aluminum carbonate D. copper(II) hypobromite E. lithium phosphate

Covalent Compounds and Their Names Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

Forming a H2 Molecule Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

H2, A Covalent Molecule In a hydrogen (H2) molecule Two hydrogen atoms share electrons to form a covalent single bond. Each H atom acquires two (2) electrons. Each H becomes stable like helium (He). Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

Diatomic Elements These elements share electrons to form diatomic covalent molecules or molecular elements Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

Electron-Dot Formulas Electron-dot formulas show The order of bonded atoms in a covalent compound. The bonding pairs of electrons between atoms. The unshared (lone) valence electrons if they exist. A central atom with an octet. Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

Electron-Dot Formulas and Models of Some Covalent Compounds Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

Names of Covalent Compounds Prefixes are used In the names of covalent compounds. Because typically two nonmetals can form two or more different compounds. Examples of compounds of N and O: NO nitrogen oxide NO2 nitrogen dioxide N2O dinitrogen oxide N2O4 dinitrogen tetroxide N2O5 dinitrogen pentoxide

Naming Covalent Compounds STEP 1 Name the first nonmetal as the element. STEP 2 End the name of the second nonmetal with -ide STEP 3 Use prefixes to show the number of atoms (subscripts). Mono is usually omitted. Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

Naming Covalent Compounds What is the name of SO3? STEP 1 The first nonmetal is S sulfur. STEP 2 The second nonmetal is O named oxide. STEP 3 The subscript 3 of O is shown as the prefix tri. SO3 → sulfur trioxide The subscript 1(for S) or mono is understood.

Naming Covalent Compounds Name P4S3 STEP 1 The first nonmetal P is phosphorus. STEP 2 The second nonmetal S is sulfide. STEP 3 The subscript 4 of P is shown as tetra. The subscript 3 of S is shown as tri. P4S3 → tetraphosphorus trisulfide

Formulas and Names of Some Covalent Compounds Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

Learning Check Select the correct name for each compound. A. SiCl4 1) 2) 3) B. P2O5 1) C. Cl2O7 1)

Learning Check Write the name of each covalent compound: CO CO2 PCl3 CCl4 N2O

Guide to Writing Formulas STEP 1 Write the symbols in the order of the elements in the name. STEP 2 Write any prefixes as subscripts. Example: 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: CS2

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

Learning Check Identify each compound as ionic or covalent and give its correct name. 1. SO3 2. MnCl2 3. (NH4)3PO3 4. Cu2CO3 5. N2O4

Learning Check Identify each compound as ionic or covalent and give its correct name. Ca3(PO4)2 FeBr3 SCl2 Cl2O