chemical bonding.....aim 3

what is the relationship between bonding and physical properties of solids?

.....aim 2

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.....aims.....

 

HW From textbook “CHEMISTRY a Contemporary Approach”

 

Some general physical properties:

·         Conductivity is the ability to carry an electrical current when electrons or ions are free to move.

·         Malleability is the ability of solids to be hammered into thin sheets.

·         Solubility is the ability to dissolve in a solvent.

·         Hardness is the ability to resist physical changes.

·         Melting point is the temperature at which a substance melts.

·         Boiling point is the temperature at which a substance boils.

 

Some physical properties of ionic solids are:

·         no conductivity because there are no free moving electrons or  ions, unless dissolved, NaCl(aq) or melted, NaCl(l)

·         not malleable because particles cannot slide pass one another

·         relatively high solubility

Ionic bonds are relatively strong therefore:

·         They are relatively hard

·         They have high melting and boiling points

 

Some physical properties of molecular (covalent) solids are:

·         no conductivity because there are no free moving electrons or  ions

·         not malleable because particles cannot slide pass one another

·         in general, relatively low or no solubility

Intermolecular forces are relatively weak therefore:

·         They are relatively soft

·         They have low melting and boiling points

 

Some physical properties of metals are:

·         relatively high conductivity because there are free moving electrons

·         malleable and ductile (can be drawn into thin wires)  because particles can slide pass one another

·         relatively low solubility

Metallic bonds are relatively strong therefore:

·         They are relatively hard

·         They have high melting and boiling points

 

TEST YOUR UNDERSTANDING

1/07

9 Solid samples of the element phosphorus can be white, black, or red in color. The variations in color are due to different

        (1) atomic masses     (2) molecular structures     (3) ionization energies     (4) nuclear charges

8/07

36 At standard pressure, a certain compound has a low boiling point and is insoluble in water. At STP, this compound most likely exists as

        (1) ionic crystals     (2) metallic crystals     (3) nonpolar molecules     (4) polar molecules

1/05

37 A substance that does not conduct electricity as a solid but does conduct electricity when melted is most likely classified as

                (1) an ionic compound (2) a molecular compound (3) a metal (4) a nonmetal

1/04

32 The data table below represents the properties determined by the analysis of substances A, B, C, and D.

Which substance is an ionic compound? (1) A (2) B (3) C (4) D

6/04

6 Which statement describes a chemical property of iron?
        (1) Iron can be flattened into sheets. (2) Iron conducts electricity and heat.  (3) Iron combines with oxygen to form rust.  (4) Iron can be drawn into a wire.

12 Conductivity in a metal results from the metal atoms having
        (1) high electronegativity (2) high ionization energy
        (3) highly mobile protons in the nucleus (4) highly mobile electrons in the valence shell

8/04

9 Which characteristic is a property of molecular substances?

                (1) good heat conductivity (2) good electrical conductivity (3) low melting point (4) high melting point

1/03

1 The high electrical conductivity of metals is primarily due to

                (1) high ionization energies   (2) filled energy levels   (3) mobile electrons  (4) high electronegativities

2  Which of the following solids has the highest melting point? (1) H2O(s)       (2) Na2O(s)     (3) SO2(s)              (4) CO2(s)

3 A chemist performs the same tests on two homogeneous white crystalline solids, A and B. The results are shown in the table below.

The results of these tests suggest that

(1) both solids contain only ionic bonds

(2) both solids contain only covalent bonds

(3) solid A contains only covalent bonds and solid B contains only ionic bonds

(4) solid A contains only ionic bonds and solid B contains only covalent bonds

 

6/03

1 Which substance contains metallic bonds? (1) Hg(l)  (2) H2O(l) (3) NaCl(s) (4) C6H12O6(s)

2 Which is a property of most nonmetallic solids?  (1) high thermal conductivity (2) high electrical conductivity (3) brittleness (4) malleability

6/02

1 Base your answers on the information below.

     Testing of an unknown solid shows that it has the properties listed below.

(1) low melting point

(2) nearly insoluble in water

(3) nonconductor of electricity

(4) relatively soft solid

    a) State the type of bonding that would be expected in the particles of this substance.

    b) Explain in terms of attractions between particles why the unknown solid has a low melting point. 

    c) Explain why the particles of this substance are nonconductors of electricity.

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