UNIT 4 – SELF TEST

Part 1: Multiple Choice with explanation:

1.     Elements of Group 1A  (a) generally form +1 cations.  (b) generally form -1 anions.  (c) do not commonly form ions.  (d) do not combine with other elements.

2.     What is the ionic charge on the manganese ion in the ionic compound that has the formula MnO2?  (a) 2+  (b) 2-  (c) 4+  (d) 4-

3.     Which element when combined with chlorine would most likely form a molecular compound?  (a) lithium  (b) carbon  (c) potassium  (d) beryllium

4.     The diatomic molecule among the following that contains a single covalent bond is:  (a) F2.  (b) O2.  (c) N2.  (d) O2-.

5.     Atoms share electrons in order to acquire the electron configurations of:  (a) alkali metals.  (b) alkaline earth metals.  (c) halogens.  (d) noble gases.

6.     The covalent molecule among the following is: (a) NaCl. (b) NH3. (c) CaO. (d) MgF2.

7.     All the elements in a particular group of the periodic table have the same number of:  (a) electrons.  (b) energy levels.  (c) valence electrons.  (d) protons.

8.     Which of the following contains a polar covalent bond?  (a) O2  (b) MgCl2  (c) HF.  (d) CaO.

9.     What type of bond would be expected in a compound of LiF?  (a) ionic bond           (b) polar covalent bond  (c) nonpolar covalent bond  (d) none of these

10.  The polar molecule among the following is:  (a) CCl4.  (b) CO2.  (c) H2O.  (d) N2.

Part 2: Matching

            Match the letters in Column B with the numbers in Column A.  Mark the appropriate letters on the Scantron form for the corresponding number.

Column A                                           Column B

18. electron dot structure            a.  empirical formula of an ionic compound

19.  VSEPR theory                     b.  a chemical formula that shows the arrangement of atoms in molecules and         polyatomic ions

20. non-polar covalent bond       c. atoms in compounds tend to acquire the electron configuration of a noble            gas

21. formula unit                          d.  characterized by equal sharing of bonding electrons

22.  polar molecule                    e.  Because electron pairs repel, molecules adjust their shapes so that the                valence-electron pairs are as far apart as possible.

23.  structural formula                ab.  a covalent bond in which one pair of electrons is shared between two atoms

24.  polar covalent bond            ac.  a molecule in which one end is slightly negative and the other end is slightly positive

25.  single covalent bond            ad.  a covalent bond formed between two different atoms in which the bonding  electrons are shared unequally

26. valence electron                    ae. two valence electrons not used in bonding

27. lone pair of electrons            bc. a depiction of valence electrons around the symbol of an element

28. octet rule                               bd. the force of attraction binding oppositely charged ions together

29.  ionic bond                            be.  an electron in the highest occupied energy level of an atom

Part 3: Problems and Questions

30.            The ionic charge of mercury, Hg, in the compound Hg2S is _________________.

31.            Atoms that have a positive charge are called ________________.

32.            The name of Mn2O3 is __________________.

33.            The polyatomic ion, NH4+ is known as _________________.

34.            Binary compounds end in the letters _________________.

35.            In naming binary molecular compounds the numbers of atoms of elements in the molecular formula are indicated by _____________.

36.            A polyatomic ion, which has the –ite or the –ate ending in the name contains the element ________________.

37.            Complete the following table.

Outer electron                       Outer electron                       Formula of ion                        Type of ion

configuration of atom            configuration of ion

K   _________________            ________________            ____________            ___________

N  _________________            ________________            ____________            ___________

Ba  _________________            ________________            ____________            ___________

Br  _________________            ________________            ____________            ___________

 

38.            For each pair of ions listed, write the correct formula and then name the compound formed by combining the two ions:

                                Ions                                         Formula                      Name

a.      Fe3+ and ClO2-

b.     Ba2+ and C2H3O2-

c.      Sn4+ and Cl-

39.            Write a skeleton equation, including states, for the reaction in which solid phosphorus reacts with oxygen to produce gaseous tetraphosphorus decoxide

 

40.            Write the formulas for the following compounds:

  1. magnesium phosphide
  2. tin(IV) oxide
  3. potassium nitrate
  4. diphosphorus trioxide
  5. carbon tetrachloride
  6. carbonic acid

41.  Name the following compounds.

  1. BaCl2
  2. KBr
  3. BaSO4
  4. NH4Cl
  5. PCl3
  6. H2S
  7. H3PO4
  8. Fe2(CO3)3

42.  From the following list select the compound that is best described by each statement, and write the formula in the blank.      H2O,  CCl4,   NH3,   CO2

  1. Which compound represents a linear molecule?
  2. Which compound best represents a tetrahedral molecule?
  3. Which compound would show a bent molecular structure?
  4. Which compound’s molecules have a pyramidal shape?

43.  Write Lewis dot structure, name the geometry or shape and determine whether the molecule is polar or not for the following compounds:

 

            Lewis Structure                        Geometry                       Molecular Polarity

            (a) H2S

            (b) CO

(c)   PO43-                                             NA

(d)   CO2

(e)  NCl3

 

PART 4: Essay (In SENTENCES respond to the following question.)

44. Distinguish between the two extremes of bonding, covalent and ionic, in terms of how each is formed, how to predict which will be formed when various elements combine and in terms of three properties of each of the resulting compounds.

45.  How do you tell the difference between ionic compounds and molecular compounds?

 

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