© 2014 Pearson Education, Inc. Chapter 6 Lecture Basic Chemistry Fourth Edition Chapter 6 Ionic and Molecular Compounds 6.5 Molecular Compounds: Sharing Electrons Learning Goal Given the formula of a molecular compound, write its correct name; given the name of a molecular compound, write its formula.

© 2014 Pearson Education, Inc. Molecular Compounds A molecular compound contains two or more nonmetals that form a covalent bond. Valence electrons are shared by nonmetal atoms in a covalent bond to achieve stability. When two or more atoms share electrons, they form a molecule.

© 2014 Pearson Education, Inc. Formation of Hydrogen Molecule In a hydrogen (H 2 ) molecule, two hydrogen atoms share electrons to form a covalent single bond each H atom acquires two (2) electrons each H becomes stable like the nearest noble gas, helium (He)

© 2014 Pearson Education, Inc. Formation of Hydrogen Molecule

© 2014 Pearson Education, Inc. Electron-Dot Formulas, Molecular Compounds In an electron-dot formula also called a Lewis structure, shared electrons or bonding pairs are shown as two dots or a single line between atoms nonbonding pairs of electrons or lone pairs, are placed next to the atom

© 2014 Pearson Education, Inc. Diatomic Elements The elements hydrogen, nitrogen, oxygen, fluorine, chlorine, bromine, and iodine exist as diatomic molecules in nature.

© 2014 Pearson Education, Inc. Sharing Electrons Between Atoms of Different Elements Electron-dot formulas for molecules with different elements show the order of bonded atoms in a covalent compound the bonding pairs of electrons between atoms the unshared (lone) valence electrons a central atom with an octet

© 2014 Pearson Education, Inc. Sharing Electrons Between Atoms of Different Elements The number of covalent bonds that a nonmetal atom forms is usually equal to the number of electrons it needs to acquire a stable electron configuration.

© 2014 Pearson Education, Inc. Electron-Dot Formulas, Molecular Compounds

© 2014 Pearson Education, Inc. Learning Check State the number of valence electrons, bonding pairs, and nonbonding pairs for each of the following molecules. MoleculesValence electrons Bonding pairs Nonbonding pairs

© 2014 Pearson Education, Inc. Solution State the number of valence electrons, bonding pairs, and nonbonding pairs for each of the following molecules. MoleculesValence electrons Bonding pairs Nonbonding pairs = (7) =

© 2014 Pearson Education, Inc. Names and Formulas, Molecular Compounds In molecular compounds, prefixes are used to indicate the number of nonmetals. The prefix mono is not used on the first nonmetal in the compound. NO 2 is nitrogen dioxide. When vowels o and o or a and o appear together, the first vowel is omitted. CO is carbon monoxide.

© 2014 Pearson Education, Inc. Names and Formulas, Molecular Compounds

© 2014 Pearson Education, Inc. Common Molecular Compounds

© 2014 Pearson Education, Inc. Guide to Naming Molecular Compounds

© 2014 Pearson Education, Inc. Learning Check Name the compound NCl 3.

© 2014 Pearson Education, Inc. Solution Name the compound NCl 3. Step 1Name the first nonmetal by its elemental name. In NCl 3, the first nonmetal (N) is nitrogen. Step 2Name the second nonmetal by using the first syllable of its element name followed by ide. The second nonmetal (Cl) is chloride.

© 2014 Pearson Education, Inc. Solution Name the compound NCl 3. Step 3Add prefixes to indicate the number of atoms (subscripts). Because there is one nitrogen atom, no prefix is needed. The subscript 3 for the Cl atoms is written as the prefix tri. The name of NCl 3 is nitrogen trichloride.

© 2014 Pearson Education, Inc. Writing Formulas from the Names of Molecular Compounds

© 2014 Pearson Education, Inc. Learning Check Write the formula for the molecular compound, diboron trioxide.

© 2014 Pearson Education, Inc. Solution Write the formula for the molecular compound, diboron trioxide. Step 1Write the symbols in the order of the elements in the name. B O Step 2Write any prefixes as subscripts. B 2 O 3

© 2014 Pearson Education, Inc. Summary of Naming Ionic and Molecular Compounds

© 2014 Pearson Education, Inc. Learning Check Name each of the following ionic or molecular compounds. A.BF 3 B.OCl 2 C.Al 2 O 3 D.Ni 3 PO 4

© 2014 Pearson Education, Inc. Solution Name each of the following ionic or molecular compounds. A.BF 3 boron trifluoride B.OCl 2 oxygen dichloride C.Al 2 O 3 aluminum oxide D.Ni 3 PO 4 nickel(I) phosphate