Ions combine to form ionic compounds.

Ions combine to form ionic compounds.
Section 4.11 Compounds That Contain Ions Ions combine to form ionic compounds. Ionic compound – a compound formed by reacting a metal (cation) with a nonmetal (anion) Properties of ionic compounds High melting points Conduct electricity If melted If dissolved in water

Ionic compounds are electrically neutral.
Section 4.11 Compounds That Contain Ions Ionic compounds are electrically neutral. The charges on the anions and cations in the compound must sum to zero.

Formulas for Ionic Compounds
Section 4.11 Compounds That Contain Ions Formulas for Ionic Compounds Write the cation element symbol followed by the anion element symbol. The number of cations and anions must be correct for their charges to sum to zero. Na Cl  NaCl Cation charge anion charge Compound net charge =

Formulas for Ionic Compounds
Section 4.11 Compounds That Contain Ions Formulas for Ionic Compounds Write the cation element symbol followed by the anion element symbol. The number of cations and anions must be correct for their charges to sum to zero.

Section 4.11 Compounds That Contain Ions Concept Check A compound contains an unknown ion X and has the formula XCl2. Ion X contains 20 electrons. What is the identity of X? a) Ti2+ b) Sc+ c) Ca2+ d) Cr2+ Z = # of e- + positive charge or Z = # of e- - negative charge The charge on the cation must be +2 since there are two Cl’s each with a –1 charge (giving an overall charge of –2 for the anion side). The cation can now be represented as X2+, containing 20 electrons. Therefore, 22 protons must be present to give a charge of +2 (+22p – 20e = +2). The element with 22 protons is titanium.

Section 4.11 Compounds That Contain Ions Concept Check A member of the alkaline earth metal family whose most stable ion contains 36 electrons forms a compound with bromine. What is the correct formula for this compound? a) CaBr2 b) KrBr c) RbBr d) SrBr2 Ionic compounds are electrically neutral. The charges on the anions and cations in the compound must sum to zero. An element in the alkaline earth metal family (Group 2) forms a +2 charge when forming a compound. Therefore two Br– ions will be required to give a net zero charge overall. 38 protons must be present to give a charge of +2 (+38p – 36e = +2). The element with 38 protons is strontium. The compound is therefore SrBr2.

Copyright©2004 by Houghton Mifflin Company. All rights reserved.
Introductory Chemistry: A Foundation FIFTH EDITION by Steven S. Zumdahl University of Illinois Copyright©2004 by Houghton Mifflin Company. All rights reserved. 1

Naming of Compounds Naming of compounds has long been necessary to identify something Names originally based upon “common names” Common name Stock system name Epsom salts Magnesium chloride Gypsum Calcium sulfate Blue vitriol Copper (II) sulfate Calomel Mercury (I) chloride Saltpeter Potassium nitrate Quicklime calcium oxide Caustic soda sodium hydroxide Copyright©2004 by Houghton Mifflin Company. All rights reserved.

An ancient painting showing Romans drinking wine.

Sugar of Lead Boiling of wine produced a thick, sweet liquid which was used as a sweetener. Actually contained lead acetate Pb(C2H3O2)2 Thought to have lead to the downfall of the Roman empire due to lead poisoning (in addition to lead water pipes) Lead poisoning causes lethargy and mental illness Copyright©2004 by Houghton Mifflin Company. All rights reserved.

Problems These common names were impractical Worldwide communication problems 4 million compounds We needed a system to “systematically” name all of these compounds, you wouldn’t have to memorize each name to know what it was. If you learn the system, you will be able to name a compound from its formula and vice versa Copyright©2004 by Houghton Mifflin Company. All rights reserved.

Common Names - Exceptions
Common names still in use today…….. H2O = water, steam, ice NH3 = ammonia CH4 = methane NaCl = table salt C12H22O11 = table sugar CaSO4•2H2O=plaster of paris Copyright©2004 by Houghton Mifflin Company. All rights reserved. 2

An artist using plaster of Paris, a gypsum plaster.
Copyright©2004 by Houghton Mifflin Company. All rights reserved. Source: Bob Daemmrick/The Image Works

Chemical names and Formulas
There are three types of ionic compounds to write formulas for and name Binary ionic compound (Type I) Transition metal compound (Type II) Ionic compound containing polyatomic ions Covalent compounds have a different naming system It uses prefixes Acids

5.1 Naming Compounds Binary ionic compounds are made up of only 2 different elements There can be more than 2 or more atoms though NaCl K2O Al2S3

5.2 Naming Compounds Binary Type I and II
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Classifying Binary Compounds
Compounds containing a metal and a nonmetal are binary ionic Type I and II Compounds containing two nonmetals are Covalent Type III Compounds containing H and a nonmetal = Acids Copyright©2004 by Houghton Mifflin Company. All rights reserved. 4

Metal Cations Type I Metals that can only have one possible charge Determine charge by position on the Periodic Table Type II Metals that can have more than one possible charge Determine metal cation’s charge from the charge on anion Copyright©2004 by Houghton Mifflin Company. All rights reserved. 6

Type I Binary Ionic Compounds
To name a binary ionic compound Write the name of the cation first (always a metal) Next, write the name of the anion, but change the ending to –ide Note that any subscripts do not change the name NaCl sodium chlorine → chloride sodium chloride

Examples potassium chloride magnesium bromide strontium oxide aluminum oxide rubidium nitride potassium iodide KCl MgBr2 SrO Al2O3 Rb3N KI Copyright©2004 by Houghton Mifflin Company. All rights reserved.

Write formulas for the following compounds
Sodium sulfide Potassium iodide Calcium bromide Aluminum oxide Rubidium selenide Na2S KI CaBr2 Al2O3 Rb2S Have students write formulas in notebook.

Type II Binary Ionic Compounds
Contain Metal Cation + Nonmetal Anion Transition metals can have various oxidation numbers or charges For example iron can be either Fe2+ or Fe3+ Metal cation name is the metal name followed by a Roman Numeral in parentheses to indicate its charge Determine charge on metal from anion charge Common Type II cations in Table 5.2 Nonmetal anion named by changing the ending on the nonmetal name to -ide Copyright©2004 by Houghton Mifflin Company. All rights reserved. 8

Examples Latin Name Systematic Name ferrous sulfide ferric sulfide cuprous oxide cupric oxide plumbous chloride plumbic chloride mercuric selenide FeS Fe2S3 Cu2O CuO PbCl2 PbCl4 Hg2Se iron (II) sulfide iron (III) sulfide copper (I) oxide copper (II) oxide lead (II) chloride lead (IV) chloride mercury (II) selenide Copyright©2004 by Houghton Mifflin Company. All rights reserved.

5.5 Naming Polyatomic ions
Polyatomic ions are ions that contain more than one atom (SO4)2- (OH)- (PO4)3- (NH4)+ It is important to note that the charge is distributed throughout all the atoms in the ion Not only on the last atom

Polyatomic Ions to be memorized!
Carbonate CO32- Nitrate NO31- Phosphate PO43- Chlorate ClO31- Bromate BrO31- Sulfate SO42- Hydroxide OH1- Ammonium NH41+ Copyright©2004 by Houghton Mifflin Company. All rights reserved.

Patterns for Polyatomic Ions
-ate ion chlorate = ClO3- -ate ion plus 1 O  same charge, per- prefix perchlorate = ClO4- -ate ion minus 1 O  same charge, -ite suffix chlorite = ClO2- -ate ion minus 2 O  same charge, hypo- prefix, -ite suffix hypochlorite = ClO- Copyright©2004 by Houghton Mifflin Company. All rights reserved. 14

5.3 Naming Compounds Binary Type III

Prefixes Drop last “a” in the prefix if the name begins with vowel
octa- 8 hepta- 7 hexa- 6 penta- 5 tetra- 4 tri- 3 di- 2 mono- (not used on first nonmetal) 1 Prefix Subscript Drop last “a” in the prefix if the name begins with vowel Copyright©2004 by Houghton Mifflin Company. All rights reserved. 11

Examples carbon monoxide carbon dioxide boron trifluoride dinitrogen pentoxide nitrogen monoxide carbon tetrachloride nitrogen dioxide CO CO2 BF3 N2O5 NO CCl4 NO2 Copyright©2004 by Houghton Mifflin Company. All rights reserved.

Copper (II) sulfate crystals.

Acids Contain H+ cation and anion Binary acids have H+ cation and a nonmetal anion Oxy (Ternary) acids have H+ cation and a polyatomic anion Copyright©2004 by Houghton Mifflin Company. All rights reserved. 15

Rules for Naming Acids cont.
When anion contains oxygen (oxyanion) the root name of the anion is used, along with ic acid for oxyanions ending in –ate ous acid for oxyanions ending in –ite H2SO4 sulfate ion Sulfur ic acid HNO3 nitrate ion Nitr ic acid HNO2 nitrite ion Nitr ous acid Copyright©2004 by Houghton Mifflin Company. All rights reserved.

Other examples HClO hypochlorite ion hypochlorous acid HClO2 chlorite ion chlorous acid HClO3 chlorate ion chloric acid HClO4 perchlorate ion perchloric acid HIO4 ?????!!!!!! Copyright©2004 by Houghton Mifflin Company. All rights reserved.

5.7 Writing Formulas from Names

Writing the Formulas from the Names
For Type III compounds, use the prefixes to determine the subscripts For Type I, Type II, polyatomic Compounds and Acids Determine the ions present Determine the charges on the cation and anion Balance the charges to get the subscripts Copyright©2004 by Houghton Mifflin Company. All rights reserved. 16

Ions combine to form ionic compounds.

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