Chapter 6 p. 194 Questions 1-25

1. a chemical bond is a link between atoms resulting from the mutual
attraction of their nuclei and electrons

2. ionic- large numbers of oppositely charges ions join because of mutual
electrical attraction
covalent- atoms joining by sharing electron pairs
metallic- join through an attraction to a sea of valence electrons

3. the greater the electronegativity difference between two atoms is, the more
ionic the bond between them is

4. a. polar refers to bonds that have an uneven distribution of charge
b. in a polar-covalent bond there is an unequal attraction of the electron
pair, resulting in one of the bonded atoms possessing a partial negative
charge and the other atom possessing a partial positive charge. In a
nonpolar-covalent bonds the electron pair is charged equally by the bonded
atoms

5. atoms will form a chemical bond if their potential energy is lowered in
doing so.

6. a molecule is a neutral group if two or more atoms, usually nonmetals, held
together by covalent bonds

7. a. the distance at which potential energy is at a minimum; bond length is
the point at which there is a balance between attraction and repulsion between
atoms in a covalent bond
b. in general higher bond energies correspond to shorter bond lengths.

8. the electrons in a covalent bond occupy overlapping orbital; each electron
is free to occupy either of the orbitals, but both are more likely to be in
the space between the nuclei of the bonded atoms.

9. a pair of electrons the is not involved in bonding but instead belongs
exclusively to one atom

10. a noble-gas configuration corresponds to a set of outer s and p orbitals
that is completely filled with a total of eight electrons. These eight outer
electrons are referred to as an octet. Atoms that possess a noble-gas
configuration are very stable because the potential energy of their electrons
is relatively low. The octet rule states that elements will gain or lose
electrons to form a noble-gas configuration.

11. a. 1 d. 6 g. 4
b. 2 e. 3
c. 2 f. 5

12. the least-electronegative atom is usually the central atom (except
hydrogen). If carbon is present, however, it is usually the central atom,
regardless of what other atoms are in a molecule.

13. a single bond involves one pair of electrons, as in the bond between
hydrogen and oxygen in water. A double bond involves two electron pairs, as
in the bond between the carbon and oxygen atoms in a molecule if carbon
dioxide. A triple bond involves three electronpairs, as in the bond between
carbon and nitrogen in hydrogen cyanide, HCN.

14. a multiple bond is needed when there are not enough valence electrons to
complete octets by adding unshared pairs.

15. a. an ionic compound is composed of cations and anions such that the total
positive and negative charges are equal.
b. most ionic compounds occur naturally as crystalline solids.

16. a. the simplest collection of atoms from which an ionic compound's formula
can be established.
b. one calcium ion Ca2+, and two flouring ions, F-

17. a. the energy released when one mole of an ionic compound is formed from
gaseous ions
b. the greater lattice energy, the stronger the ionic bonding

18. a. ionic compounds have higher melting and boiling points that molecular
compounds do, and they do not tens to vaporize as readily at room temperature
b. the difference in the properties of ionic and molecular compounds are
generally a result of differences in how strongly the compounds' basic units
are held together
c. hardness, brittleness, electrical conductivity in molten state

19. a. a charged group of covalently bonded atoms
b. some common examples of polyatomic anions include the nitrate ion, NO3-.
The ammonium ion, NH4+, the sulfate ion SO4-, the phosphate ion, PO4 3-
c. polyatomic ions combine with ions of opposite charges to form ionic
compounds.

20. a. Metals are better conductors of heat that ionic or molecular
compounds. In the solid state, metals are more easily deforms and are better
electrical conductors that solid ionic or molecular compounds. Unlike ionic
and molecular compounds, metals are also shiny in appearance.
b. metals are good electrical conductors because of the presence of highly
mobile electrons with in the bonding network of their atoms.

21. they contain sparsely populated outer most orbitals, they have low
ionization energies and they have lower electronegativities.

22. a. metallic bonding results from the attraction between metal atoms and
a sea of surrounding electrons.
b. metal's heat of vaporization is a measure of the strength of the
metal's bonding.

Covalent Bonding and Molecular Geometry

23. a. according to VSEPR theory, the shapes of molecules are classified
based on the number of bonding electron pairs and lone pairs that surround a
molecule's central atom
b. both molecules are linear

24. a. linear
b. trigonal-planar
c. tetrahedral
d. trigonal-bipyramidal
e. octahedral

25. a. unshared electron pairs occupy space and bonded electrons do, but
they are not part of the visualized molecular geometry.
b. Double and triple bonds are treated the same as single bonds.