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Name: __________AP Unit 3: IM Forces and States of Matter
Types of Solids Handout 2
Covalent Network Solids
Diamond Graphite Silicon carbide
Another version of diamond:
Ionic solidsYou should now be able to make some educated guesses about ionic solids and the types of properties they will have based on their structure. See if you can fill in the blanks and make some predictions below!
Composed of …
________________________ attracted to one another via __________________________.
Melting Points …
Generally _____________ compared to other solids.
Which has the higher melting point in the following pairs of ionic compounds? WHY???Remember what determines the strength of Coulombic attraction:
1. Magnitudes of the charges (greater magnitude = stronger attraction)2. Distance between the charges (shorter distance = stronger attraction)
NaCl or NaF
MgO or AlN
Electrical Conductivity …Electrical conductivity of ionic solids depends on the state. Use evidence from the models below to support your response.
Do solid ionic substances conduct? WHY?
Draw what the LiCl sample would look like if it was molten. Would it conduct electricity then? WHY?
Do dissolved ionic substances conduct? WHY?
Na+1 Cl-1 Cl-1 F-1Na+1 Na+1 F-1Na+1
O-2Mg+2 O-2Mg+2 Al+3 N-3 Al+3 N-3
Name: __________AP Unit 3: IM Forces and States of Matter
Understanding Check
Answer the following questions concerning solids and their properties:
1. For each of the following pairs of solid substances given below, identify which would have the higher melting point and why.
a. Ethanol, C2H5OH vs. Ethane, C2H6
b. Water vs. Ammonia, NH3
c. Silicon carbide, SiC vs. Sucrose, C12H22O12
d. Acetone, C3H6O vs. magnesium oxide, MgO
e. Magnesium oxide, MgO vs. Sodium oxide, Na2O
f. Magnesium oxide, MgO vs. strontium oxide, SrO
2. The solid structure of ethanol is shown below.
a. Label any intermolecular and intramolecular forces.
b. Rank these forces from strongest to weakest.
c. Which of these forces will be broken as solid ethanol melts?
d. Which of these forces will be broken as ethanolmolecules are decomposed into CO2 and H2O?
e. Which of the processes described in part c. and part d. requires more energy? Justify your response.
3. Draw 3-4 ammonia molecules in a correct orientation to show the formation of attractive forces between them in the solid state.
4. Question 2 references solid ethanol and question 3 references solid ammonia. What is the key difference in the solid structures of each substance that explains why ethanol has a higher boiling point? Reference specific features of each model in your answer.
5. Draw a simple representation of solid calcium oxide. Include no more than 8 formula units of calcium oxide in your model. Your drawing must include the following details:
a. Identity of the ions (symbol and charge)b. The arrangement and proper orientation of the ionsc. The relative sizes of each ion
d. Will solid calcium oxide conduct electricity? Justify your response with specific references to your diagram.
e. What changes could be made to calcium oxide that would allow electricity to flow?
6. A model of the solid structure of silicon oxide is shown below. The larger atoms are silicon and the smaller atoms are oxygen.
a. What type of solid is silicon oxide?b. How many oxygen atoms is every silicon atom bonded to?c. What types of interparticle forces exist that hold these atoms together?d. Would you expect this substance to be thermally conductive? Justify your response.
Name: _____KEY_____AP Unit 3: IM Forces and States of Matter
Understanding Check
1. For each of the following pairs of solid substances given below, identify which would have the higher melting point and why.
a. Ethanol, C2H5OH vs. Ethane, C2H6
Ethanol molecules will experience H-bonding between molecules while ethane molecules will experience London dispersion forces. Since the H-bonds are expected to be stronger than LD forces, more heat will be required to overcome them and melt ethanol.
b. Water vs. Ammonia, NH3
Water molecules and ammonia molecules will both experience H-bonding, but since water is a more polar molecule than ammonia, its H-bonds will be stronger. It will therefore require more heat to overcome the H-bonds in water, leading to a higher melting point.
c. Silicon carbide, SiC vs. Sucrose, C12H22O12
Silicon carbide is a covalent network solid, so the atoms are held together by strong covalent bonds. In solid sucrose, the molecules experience only Hydrogen bonding. Since the covalent bonds are much stronger and much harder to overcome, SiC will have the higher melting point.
d. Acetone, C3H6O vs. magnesium oxide, MgOMagnesium oxide is an ionic solid while acetone is a molecular solid. The ions in magnesium oxide are held together by strong ionic bonds, while the molecules in acetone are only held together by weaker dipole-dipole forces. More heat will be required to overcome the strong ionic bonds in magnesium oxide.
e. Magnesium oxide, MgO vs. Sodium oxide, Na2OBoth substances are ionic solids, but since the magnitudes of the charges in MgO are greater (Mg+2 and O-2), they will be more strongly attracted. More heat is therefore required to melt MgO.
f. Magnesium oxide, MgO vs. strontium oxide, SrOBoth substances are ionic solids, and the ions in each substance are of equal magnitude (+2 and -2). Magnesium however, is smaller than strontium, so will the bond will be shorter and stronger. More heat is therefore required to melt MgO.
2. The solid structure of ethanol is shown below.
a. Label any intermolecular and intramolecular forces.
b. Rank these forces from strongest to weakest.Weakest = inter. = H-bondsStrongest = intra. = covalent bonds
c. Which of these forces will be broken as solid ethanol melts?H-bonds only
d. Which of these forces will be broken as ethanolmolecules are decomposed into CO2 and H2O?Covalent bonds will be broken
e. Which of the processes described in part c. and part d. requires more energy? Justify your response. Since covalent bonds are stronger, more energy is required in part d
3. Draw 3-4 ammonia molecules in a correct orientation to show the formation of attractive forces between them in the solid state.
4. Question 2 references solid ethanol and question 3 references solid ammonia. What is the key difference in the solid structures of each substance that explains why ethanol has a higher boiling point? Reference specific features of each model in your answer.
Both molecules are polar, so will be attracted to one another by Hydrogen bonds. Ethanol however, is more polar, so it’s H-bonds will be stronger than ammonia’s and more heat will be required to break them in the boiling process.
5. Draw a simple representation of solid calcium oxide. Include no more than 8 formula units of calcium oxide in your model. Your drawing must include the following details:
a. Identity of the ions (symbol and charge)b. The arrangement and proper orientation of the ionsc. The relative sizes of each ion
Calcium must be larger than oxygenThe symbols Ca and O must be presentThe charges +2 and -2 must be presentThe cations must be next to anions
d. Will solid calcium oxide conduct electricity? Justify your response with specific references to your diagram.
Calcium oxide does have charged particles, but they can not flow freely so will not conduct electricity
e. What changes could be made to calcium oxide that would allow electricity to flow?
The calcium oxide could be melted or dissolved. Then the charged ions would be able to move and electrical conduction would be possible.
6. A model of the solid structure of silicon oxide is shown below. The larger atoms are silicon and the smaller atoms are oxygen.
a. What type of solid is silicon oxide? Covalent network solidb. How many oxygen atoms is every silicon atom bonded to? 4 other O atomsc. What types of interparticle forces exist that hold these atoms together?
Covalent bondsd. Would you expect this substance to be thermally conductive? Justify your response.
No, it will be a thermal insulator. Since each atom is covalently bondedto many other atoms, it will difficult to increase the motion of the particles.
H-bond
Ca+2
Ca+2
Ca+2
O-2 O-2
O-2
