Chapter 2 Atoms, Molecules, and Ions Chemistry: McMurry and Fay, 6th Edition Chapter 2: Atoms, Molecules, and Ions 4/7/2019 12:08:59 AM Chapter 2 Atoms, Molecules, and Ions Copyright © 2011 Pearson Prentice Hall, Inc.

Compounds and Mixtures Chapter 2: Atoms, Molecules, and Ions 4/7/2019 Compounds and Mixtures Different compositions Same compositions The same number of protons Cannot be separated physically Variable properties Similar properties Copyright © 2008 Pearson Prentice Hall, Inc. Copyright © 2008 Pearson Prentice Hall, Inc.

Molecules and Covalent Bonds Chemistry: McMurry and Fay, 6th Edition Chapter 2: Atoms, Molecules, and Ions 4/7/2019 12:08:59 AM Molecules and Covalent Bonds Covalent Bond: Results when two atoms share several (usually two) electrons. Typically a nonmetal bonded to a nonmetal Molecule: The unit of matter that results when two or more atoms are joined by covalent bonds. Copyright © 2011 Pearson Prentice Hall, Inc.

Molecules and Covalent Bonds Chemistry: McMurry and Fay, 6th Edition Chapter 2: Atoms, Molecules, and Ions 4/7/2019 12:08:59 AM Molecules and Covalent Bonds Insert Figure 2.12 p56 Copyright © 2011 Pearson Prentice Hall, Inc.

Chemistry: McMurry and Fay, 6th Edition Chapter 2: Atoms, Molecules, and Ions 4/7/2019 12:08:59 AM Ions and Ionic Bonds Ionic Bond: A transfer of one or more electrons from one atom to another. A strong electrical attraction between charged particles. Typically a metal bonded to a nonmetal. Ion: A charged particle Cation: A positively charged particle. Metals tend to form cations. Anion: A negatively charged particle. Nonmetals tend to form anions. Copyright © 2011 Pearson Prentice Hall, Inc.

Molecules, Ions, and Chemical Bonds Chapter 2: Atoms, Molecules, and Ions 4/7/2019 Molecules, Ions, and Chemical Bonds In the formation of sodium chloride, one electron is transferred from the sodium atom to the chlorine atom. 11 protons 11 electrons 17 protons 17 electrons Na1+ + Cl1- Na + Cl Sodium- very reactive in water! Chlorine gas- can kill someone (Fritz Haber, WWI). Sodium chloride- preservative, common food additive. 11 protons 10 electrons 17 protons 18 electrons Copyright © 2008 Pearson Prentice Hall, Inc.

Naming Chemical Compounds Chemistry: McMurry and Fay, 6th Edition Chapter 2: Atoms, Molecules, and Ions 4/7/2019 12:08:59 AM Naming Chemical Compounds Cation Charges for Typical Main-Group Ions 1+ 2+ 3+ Metals tend to form cations. Note some in 3A and 4A with multiple charges. Copyright © 2011 Pearson Prentice Hall, Inc.

Naming Chemical Compounds Chemistry: McMurry and Fay, 6th Edition Chapter 2: Atoms, Molecules, and Ions Naming Chemical Compounds 4/7/2019 12:08:59 AM Anion Charges for Typical Main-Group Ions 3- 2- 1- Nonmetals tend to form anions. Noble gases do not naturally form ions in this sense. © 2012 Pearson Education, Inc. Copyright © 2011 Pearson Prentice Hall, Inc.

Naming Ionic Compounds To name a compound that contains two elements, identify the cation and anion. name the cation first, followed by the name of the anion with an –ide ending.

Naming Chemical Compounds Chemistry: McMurry and Fay, 6th Edition Chapter 2: Atoms, Molecules, and Ions 4/7/2019 12:08:59 AM Naming Chemical Compounds Ionic Compound: A neutral compound in which the total number of positive charges must equal the total number of negative charges. Binary Ionic Compounds sodium chloride: Na+ Cl- NaCl magnesium oxide: Mg2+ O2- MgO aluminum sulfide: Al3+ S2- Al2S3 Copyright © 2011 Pearson Prentice Hall, Inc.

Naming Chemical Compounds Chemistry: McMurry and Fay, 6th Edition Chapter 2: Atoms, Molecules, and Ions 4/7/2019 12:08:59 AM Naming Chemical Compounds Some transition metals form more than one cation Copyright © 2011 Pearson Prentice Hall, Inc.

Naming Chemical Compounds Chemistry: McMurry and Fay, 6th Edition Chapter 2: Atoms, Molecules, and Ions 4/7/2019 12:08:59 AM Naming Chemical Compounds Use Roman numerals in parentheses to indicate the charge on metals that form more than one kind of cation. Binary Ionic Compounds iron(III) oxide: Fe3+ O2- Fe2O3 The common system (stannous, stannic, etc.) is still used but its use is becoming less frequent. tin(II) chloride: Sn2+ Cl- SnCl2 lead(II) fluoride: Pb2+ F- PbF2 Copyright © 2011 Pearson Prentice Hall, Inc.

Example Write the formula and names of the following compounds: 1) K+ and Br- 2) Ca2+ and O2- 3) Pb4+ and S2- 4) Cu2+ and F-

Naming Chemical Compounds Chemistry: McMurry and Fay, 6th Edition Chapter 2: Atoms, Molecules, and Ions 4/7/2019 12:08:59 AM Naming Chemical Compounds Binary Molecular Compounds Because nonmetals often combine with one another in different proportions to form different compounds, numerical prefixes are usually included in the names of binary molecular compounds. Copyright © 2011 Pearson Prentice Hall, Inc.

Naming Chemical Compounds Chapter 2: Atoms, Molecules, and Ions 4/7/2019 Naming Chemical Compounds N2F4 The first element listed is more cationlike and takes the name of the element. The second element listed is more anionlike and takes the name of the element with an “ide” modification to the ending. The prefix is added to the front of each to indicate the number of each atom. dinitrogen tetrafluoride Copyright © 2008 Pearson Prentice Hall, Inc.

Naming Chemical Compounds Chapter 2: Atoms, Molecules, and Ions 4/7/2019 Naming Chemical Compounds Binary Molecular Compounds Whenever the prefix ends in “a” or “o” and the element name begins with a vowel, drop the “a” or “o” in the prefix. N2O4 dinitrogen tetroxide Whenever the prefix for the first element is “mono,” drop it. CO2 carbon dioxide CO carbon monoxide Copyright © 2008 Pearson Prentice Hall, Inc.

Learning Check Write the name of each covalent compound. P2O5 _____________________ SiCl4 _____________________ CCl4 _____________________ N2O _____________________

Naming Chemical Compounds Chemistry: McMurry and Fay, 6th Edition Chapter 2: Atoms, Molecules, and Ions 4/7/2019 12:09:00 AM Naming Chemical Compounds Polyatomic ions are covalently bonded atoms with a net charge. Copyright © 2011 Pearson Prentice Hall, Inc.

Naming Chemical Compounds Chemistry: McMurry and Fay, 6th Edition Chapter 2: Atoms, Molecules, and Ions 4/7/2019 12:09:00 AM Naming Chemical Compounds Polyatomic Ionic Compounds sodium hydroxide: Na+ OH- NaOH magnesium carbonate: Mg2+ CO32- MgCO3 sodium carbonate: Na+ CO32- Na2CO3 iron(II) hydroxide: Fe2+ OH- Fe(OH)2 Copyright © 2011 Pearson Prentice Hall, Inc.

Learning Check Write formula and name of the following compounds: A. Mg2+ and NO3- B. Al3+ and BrO3- C. Fe2+ and SO42- D. Ba2+ and PO32-

Examples Write the correct formula for each. A. aluminum nitrate B. copper(II) nitrate C. iron(III) hydrogen sulfite D. tin(IV) hydroxide