Unit 9 Metallic Bonding Table of Contents Table of Contents 1 Essential Questions 3 Review 3 Lesson 9.1: Metallic Compounds 5 Objective 5 Warm-Up 5 Learn about It 6 Key Points 9 Web Links 10 Check Your Understanding 10 Challenge Yourself 12 Lesson 9.2: Properties of Metallic Compounds 13 Objectives 13 Warm-Up 13 Learn about It 14 Key Points 19 Web Links 19 Check Your Understanding 20 Challenge Yourself 21 Laboratory Activity 22 Performance Task 24 Self Check 26 Key Words 26 Wrap Up 28 References 28
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Review 3
Lesson 9.1: Metallic Compounds 5 Objective 5 Warm-Up 5 Learn about It 6 Key Points 9 Web Links 10 Check Your Understanding 10 Challenge Yourself 12
Lesson 9.2: Properties of Metallic Compounds 13 Objectives 13 Warm-Up 13 Learn about It 14 Key Points 19 Web Links 19 Check Your Understanding 20 Challenge Yourself 21
Laboratory Activity 22
Performance Task 24
Self Check 26
Key Words 26
Wrap Up 28
Unit 9 Metallic Bonding
conductors of electricity and heat. Furthermore, their ability to be drawn into thin wires and to be hammered into thin sheets show that the bonds between two metallic atoms are strong yet flexible. Alloys used in airplane turbines and conductors in electrical cells are just few examples of fantastic materials we can derive from metals. But why are metals capable of these things? Why can copper, for example, exhibit ductility and be drawn into thin wires? In this unit, you will learn about how metals are structured, and how do their structures explain their wonderful properties. This unit describes the another type of chemical bonding known as metallic bonding which is present between metals. Ultimately, this chapter will help you distinguish different types of compounds based on some properties that differentiate metallic, ionic and covalent compounds.
Essential Questions
At the end of this unit, you should be able to answer the following questions.
Review
An element is composed of only one kind of atom. It can be classified as metals, nonmetals, and metalloids. Compounds are substances made up of at least two or more elements chemically combined.
Valence electrons are the most important electrons of an element, mainly because they are directly involved in bonding. These are electrons found at the outermost shell of an atom which are lost, gained or shared to satisfy octet.
o A cation is a positively-charged atom, as a result of losing at least one electron in its valence shell.
o Anion – negatively-charged atom, as a result of gaining at least one electron in its valence shell.
Covalent compounds are compounds that form as a result of covalent bonding, wherein two atoms share their valence electrons.
describe the electron sea model of metals.
Metals can be distinguished from nonmetals based on their properties. Metals are electrically and thermally conductive, and they are also malleable, ductile and lustrous, unlike nonmetals. These properties can be explained by the structure of metallic compounds. Metallic compounds, or simply metals, are held together by metallic bonds. How are metals bonded together?
Warm-Up Metallic Bonding Metallic bonding exists between two metals. Let us consider the case where the metals are identical. Let us look at an aluminum atom. Fill up the table below.
Chemical element Aluminum
Valence electron configuration
Lewis electron-dot formula
1. Based on your answers for the table above, what is the easiest way
aluminum could attain an octet? ________________________________________________________________________________ ________________________________________________________________________________
3. Based from your answer on number 2, is it possible for two aluminum atoms to form a covalent compound? Why or why not? ________________________________________________________________________________ ________________________________________________________________________________
Learn about It
hand, sharing electrons is also not an option. Even if they share all electrons from both metals, they will still lack some electrons to complete the octet. Representative metals are known to obey octet rule, and this inconsistency suggests that covalent bonding is not also suitable to explain the interaction between them. This opens up the idea that most likely, a third type of bonding is involved. The Electron Sea Model The atoms in a metal, when they bond together, form a metallic bond. In a metallic bond, the valence shells of a component atom overlaps with another one, much like in a covalent bond. However, unlike a covalent compound which only involves a few atoms to form a bond, multiple metal atoms surround each other in order to share their valence electrons simultaneously. This happens when a metal atom starts freeing valence electron to move around and create a domino effect to its neighboring electrons. Although the metal which loses the electron becomes incompletely filled, the vacated spot will be completely filled by another moving electron. In this scenario, electrons are said to be delocalized, or free to move from one atom to another. This results to a picture of bonding, wherein metallic cations, are fixed and embedded in a lattice surrounded by a sea of valence electrons. This is depicted in the following illustration.
Fig. 1. Metallic bonding. Metal cations embedded in a sea of valence electrons.
Metallic bonding is not limited to one type of metal. Alloys, or solid homogeneous mixtures of metals, are formed by mixing two different metals together. Alloys modify properties of the original metal, enhancing strength, conductivity, or any other way depending on the application.
Copyright © 2018 Quipper Limited 6
Substitutional alloys, are alloys in which the atoms of one element substitute for the atoms of the other element in the alloy. This occurs when two metals of roughly the same atomic size are mixed together. Examples of this alloy are brass (combination of copper and zinc) and bronze (combination of copper and aluminum).
Fig 2. Substitutional alloy.
Interstitial alloys, on the other hand, are alloys in which the atoms of one element is placed in between the spaces of the atoms of the other element. This occurs when one metal’s atoms are smaller than the atoms of the other metal. An example of interstitial alloys is steel, which is a combination of iron and carbon.
Fig 3. Interstitial alloy.
Examples of alloys and their uses are listed below.
Table 9.1. Various types and uses of alloys. Alloy Combination of metal Uses
Bronze Copper and aluminum Used in sculptures, musical instruments, and
medals
automobiles and appliances
Brass Copper and zinc Used in plumbing, musical instruments, and
home furnitures
Amalgam Mercury and silver Used in electrolytic cells, extraction of gold, and dentistry (cavity filler)
Pewter Tin and antimony Used in decoration, jewelry, and tableware
Solder Tin and lead Used in connecting electronic parts and
plumbing
Metallic bonding is formed when metal atoms free their valence electrons, producing a sea of electrons which they can all share.
Alloys are solid homogeneous mixtures of metals formed by mixing two different metals together.
Substitutional alloys are alloys in which the atoms of one element substitute for the atoms of the other element in the alloy.
Check Your Understanding
A. Write true if the statement is true. Otherwise, write false.
4. Metallic bonding between atoms occur because of valence shell overlap between multiple atoms.
5. Metallic bonding allows inner core electrons, as well as valence electrons, to freely move about.
B. Assess whether the following sentences describe a substitutional or an
interstitial alloy. Write S if the sentence describes a substitutional alloy. Write I if the sentence describes an interstitial alloy. Write A if the sentence describes both alloy type. Write N if it doesn’t describe an alloy.
1. A piece of solid is made up of positively-charged copper and negatively- charged chlorine.
2. Alloys modify properties of the original metal, enhancing both strength and conductivity,
3. Brass is an example of this alloy. 4. This type of alloy is made up of atoms with relatively similar sizes. 5. These are solid, homogeneous mixtures of metals. 6. The positively-charged ion is surrounded by negatively-charged ions in
almost all directions. 7. The electrons are collectively shared between iron and carbon. 8. Multiple bonds are formed to satisfy the octet between two rhenium atoms. 9. The protons are moving from one position to another in this type of alloy. 10.Electrons are delocalized between two metal atoms.
C. For the next few questions, refer to the figure below. Answer the next few
questions.
Answer the following questions comprehensively.
1. Steel is a compound of iron and carbon. Why do you think steel is considered an alloy, as opposed to an ionic or covalent compound?
2. Graphene, a 2D sheet of carbon atoms bonded together in a lattice, is electrically conductive, harder than steel, and has a very high melting point. Despite carbon being a nonmetal, why do you think Graphene possesses these properties?
For the following combination of metals, identify what type of alloy will be formed. You can look and compare the sizes of the ions that can form from each metals to identify the type of alloy.
3. Cu and Al 4. Hg and Ag
Objectives In this lesson, you should be able to:
explain the properties of metals in terms of the electron sea model; and
Making a Sea of Electron Materials:
5 pieces each of red and blue balls, of different sizes 5 ft. wires glue or adhesives
Learn about It
Conductivity Conductivity is the ability of a material to allow heat or electric current to easily pass through. Electricity, on the other hand, is the flow of electric charge brought by the movement of electrons. Whenever electricity or heat passes through metals, it can freely flow without much obstruction from the positive nuclei of atoms. Hence, metals and alloys are electrically and thermally conductive.
Fig 4. Cooking pans are made up of metals which can transfer heat.
transfer of electricity. Electrons also carry energy while travelling which allows the transfer of heat. Density and Tensile Strength Metals are very dense, as shown in the table below. They also have high tensile strength, hence they are used as construction materials. Their high densities and high tensile strength suggest that metallic bond is very strong. This allows the atoms inside metals to pack tightly, producing rigid structures.
Table 9.2 Densities of some metals. The density of water is 1 g/cm3.
Metal Density (g/cm3)
Fig 6. High tension wires which hold the tension bridges are usually made up of
Luster
Key Points
Metals are good conductors of heat and electricity. The delocalized electrons
allows transfer of electricity, and heat is carried by the electrons as it travels from one place to another.
Metals are very dense and have high tensile strength, indicative of the immense strength of metallic bonds.
Metals have high melting and boiling points. Since metal cations are attracted to a sea of electrons, greater energy is needed to melt and boil metals.
Metals and alloys are malleable and ductile. When atoms are under stress, the delocalized electrons allow for the metal atoms to simply slide over one another without breaking the metallic bond.
Check Your Understanding
A. Write true if the statement is true. Write false otherwise.
1. Metals are ductile and malleable because cations can move about without breaking bonds.
2. Metals have high boiling points. 3. Metals can conduct electricity because electrons can freely move about the
bulk of the metal. 4. Metals do not allow electric current to flow unimpeded. 5. Metals have low melting points
B. Identify if the following physical properties describe a metal or not. Write M if it
pertains to a property of metal, and N if not. 1. Electrical wires are used to transfer electricity from a source to your
household devices. 2. Coal transfers heat to the grilled liempo. 3. Pencil lead are good conductors of electricity. 4. Metallic particles float in water. 5. Metal sheets are found in heating materials and containers. 6. Aluminum foil is used to grill bangus. 7. Diamond conducts electricity and heat. 8. Oven uses gaseous metal to transfer heat and bake cakes. 9. Tin cans can be reshaped by hammering. 10.Liquid mercury conducts electricity even in liquid form.
Answer the following questions comprehensively. 1. Differentiate a metallic bond from a covalent bond. 2. Which of the three bond types do you think is the strongest? Why? 3. Metals form metallic bonds, nonmetals form covalent bonds, and metals and
nonmetals form ionic bonds. How do you think metalloids form their bonds? 4. The conductivity of metals at very low temperatures increases to a point, that
it achieves a state called superconductivity. Based on what you know about metallic bonding, why is this so?
Properties of Metals
Objective At the end of this laboratory activity, the students should be able to:
observe properties of household metallic compounds. Materials and Equipment
stainless steel copper wire aluminum foil iron nail mossy zinc tin can charcoal hammer ziplock bags water beaker or container watch glass
Procedure Observation of Physical Properties
1. Observe the color of stainless steel, copper wire, aluminum foil, iron nail, mossy zinc, tin can and charcoal. Record your observations on the table below.
2. Similarly, observe if these solids exhibit luster. Record your observations on the table below. Put a check mark if the solid exhibits luster, and cross mark if the solid does not.
Test for Hardness and Malleability 1. Take a small amount of steel, copper wire, aluminum foil, iron nail, mossy
zinc, tin can and charcoal on separate ziplock bags. 2. Close the ziplock bags. Using a hammer, carefully pound the solids inside the
ziplock bags. Observe what happens to the solids. Continue pounding until no more changes occur.
3. Record your observations on the table below. Test for Conductivity
1. Take a small amount of steel, copper wire, aluminum foil, iron nail, mossy zinc and charcoal. Place it in separate watch glasses.
2. Using an improvised electrical conductivity set-up, test the conductivity of each solid. Touch the solids using the loose ends of the set-up. Observe if the flashlight or bulb lights up.
Waste Disposal Dispose solids in a regular trash bin. Dispose all solutions in sink with excessive amount of running water.
Data and Results (or Observation) Record your observations on the table below.
Table 1. Properties of household metals.
Household material
Exhibit luster?
Guide Questions
1. Which solids sink on water? What property is this associated with? 2. Which solids exhibit luster? Explain why these solids shine with light. 3. What can you say about the hardness of each solids? Compare it with
charcoal. 4. Which solids are malleable? Explain how can they be able to resist physical
stress. 5. Which solids are able to light up the bulb? Explain why they can light up the
bulb even at the solid state.
Performance Task
Knowing the Bond Type Your school launched a weeklong celebration called The Mystery Week. It’s an event that fosters skills development, critical thinking and creativity. The Chemistry department hosted the main activity of the week, a brain tickling puzzle about the identities of three different solids. You are part of a group of young science enthusiasts. Your group take the challenge. The Chemistry department wanted to test your chemistry skills and asked you to identify what types of bonds are present in each solids. Goal
Your task is to design a method in identifying the type of chemical bond present in each solid .
Role You are part of a group of young science enthusiasts.
Audience
Your audience is the Chemistry department. Situation
You have three different solids, labelled A, B and C. A is a thin silver sheet, while B and C are white powdery solids.
Each solids just weigh exactly 1 gram. Product/Performance and Purpose:
You will conduct a series of experiment to be able to find out what types of bonds are present in each solid.
You will explain your methods and how did you arrive to the conclusion on what type of bond each solid contains.
Standards and Criteria for Success
Your work must meet the standards found in the rubric below. Rubrics for Assessment
Criteria Below Expectations 0% to 49%
Needs Improvement 50% to 74%
Successful Performance 75 to 99%
Exemplary Performance 100%
Comprehensiveness Methods does not justify the objectives
Shows some comprehensive- ness, but most methods are not in line with the objectives
Comprehensive, some methods meet the objectives but are not planned well
Very comprehensive, method carefully planned out and techniques meet the objectives
Reliability Methods produced no data
Shows some reliability, data can be gathered but cannot be analyzed further
Reliable, data gathering and analysis offers reliable results but sometimes show inconsistencies
Shows some originality, inadequate used of resources
Original ideas, adequate use of resources
Very original, shows imaginative use of resources
After studying the unit, can you now do the following?
Check I can…
Recognize and explain properties of metals and alloys
Explain why copper can be drawn in thin wires
Reflect
Metallic compounds These are compounds made up of metals.
Delocalized electrons These are electrons which are free to move from one atom to another.
Alloys These are solid homogeneous mixtures of metals formed by mixing two different metals together.
Substitutional alloys These are substituted alloys in which the atoms of one element substitute for the atoms of the other element in the alloy.
Interstitial alloys These are substituted alloys in which the atoms of one element is placed in between the spaces of the atoms of the other element.
Sea of Electron Model This describes metals as metal cations suspended in a sea of mobile electrons. The electrons are collectively shared to satisfy octet.
Malleability It is the ability of a material to be formed into sheets without breaking apart
Clackamas Community College. “Metallic Bonding”. Accessed 3 Jul 2017. http://dl.clackamas.edu/ch104-07/metallic.htm Chang, Raymond and Kenneth A. Goldsby. 2016. Chemistry. New York, NY: McGraw-Hill Education. Silberberg, Martin. 2009. Chemistry: The Molecular Nature of Matter and Change, 5th edition. Department of Education, Republic of the Philippines. EASE II Module 14: The Chemical Bonds. 2014. Republic of the Philippines.
Lesson 9.1: Metallic Compounds 5 Objective 5 Warm-Up 5 Learn about It 6 Key Points 9 Web Links 10 Check Your Understanding 10 Challenge Yourself 12
Lesson 9.2: Properties of Metallic Compounds 13 Objectives 13 Warm-Up 13 Learn about It 14 Key Points 19 Web Links 19 Check Your Understanding 20 Challenge Yourself 21
Laboratory Activity 22
Performance Task 24
Self Check 26
Key Words 26
Wrap Up 28
Unit 9 Metallic Bonding
conductors of electricity and heat. Furthermore, their ability to be drawn into thin wires and to be hammered into thin sheets show that the bonds between two metallic atoms are strong yet flexible. Alloys used in airplane turbines and conductors in electrical cells are just few examples of fantastic materials we can derive from metals. But why are metals capable of these things? Why can copper, for example, exhibit ductility and be drawn into thin wires? In this unit, you will learn about how metals are structured, and how do their structures explain their wonderful properties. This unit describes the another type of chemical bonding known as metallic bonding which is present between metals. Ultimately, this chapter will help you distinguish different types of compounds based on some properties that differentiate metallic, ionic and covalent compounds.
Essential Questions
At the end of this unit, you should be able to answer the following questions.
Review
An element is composed of only one kind of atom. It can be classified as metals, nonmetals, and metalloids. Compounds are substances made up of at least two or more elements chemically combined.
Valence electrons are the most important electrons of an element, mainly because they are directly involved in bonding. These are electrons found at the outermost shell of an atom which are lost, gained or shared to satisfy octet.
o A cation is a positively-charged atom, as a result of losing at least one electron in its valence shell.
o Anion – negatively-charged atom, as a result of gaining at least one electron in its valence shell.
Covalent compounds are compounds that form as a result of covalent bonding, wherein two atoms share their valence electrons.
describe the electron sea model of metals.
Metals can be distinguished from nonmetals based on their properties. Metals are electrically and thermally conductive, and they are also malleable, ductile and lustrous, unlike nonmetals. These properties can be explained by the structure of metallic compounds. Metallic compounds, or simply metals, are held together by metallic bonds. How are metals bonded together?
Warm-Up Metallic Bonding Metallic bonding exists between two metals. Let us consider the case where the metals are identical. Let us look at an aluminum atom. Fill up the table below.
Chemical element Aluminum
Valence electron configuration
Lewis electron-dot formula
1. Based on your answers for the table above, what is the easiest way
aluminum could attain an octet? ________________________________________________________________________________ ________________________________________________________________________________
3. Based from your answer on number 2, is it possible for two aluminum atoms to form a covalent compound? Why or why not? ________________________________________________________________________________ ________________________________________________________________________________
Learn about It
hand, sharing electrons is also not an option. Even if they share all electrons from both metals, they will still lack some electrons to complete the octet. Representative metals are known to obey octet rule, and this inconsistency suggests that covalent bonding is not also suitable to explain the interaction between them. This opens up the idea that most likely, a third type of bonding is involved. The Electron Sea Model The atoms in a metal, when they bond together, form a metallic bond. In a metallic bond, the valence shells of a component atom overlaps with another one, much like in a covalent bond. However, unlike a covalent compound which only involves a few atoms to form a bond, multiple metal atoms surround each other in order to share their valence electrons simultaneously. This happens when a metal atom starts freeing valence electron to move around and create a domino effect to its neighboring electrons. Although the metal which loses the electron becomes incompletely filled, the vacated spot will be completely filled by another moving electron. In this scenario, electrons are said to be delocalized, or free to move from one atom to another. This results to a picture of bonding, wherein metallic cations, are fixed and embedded in a lattice surrounded by a sea of valence electrons. This is depicted in the following illustration.
Fig. 1. Metallic bonding. Metal cations embedded in a sea of valence electrons.
Metallic bonding is not limited to one type of metal. Alloys, or solid homogeneous mixtures of metals, are formed by mixing two different metals together. Alloys modify properties of the original metal, enhancing strength, conductivity, or any other way depending on the application.
Copyright © 2018 Quipper Limited 6
Substitutional alloys, are alloys in which the atoms of one element substitute for the atoms of the other element in the alloy. This occurs when two metals of roughly the same atomic size are mixed together. Examples of this alloy are brass (combination of copper and zinc) and bronze (combination of copper and aluminum).
Fig 2. Substitutional alloy.
Interstitial alloys, on the other hand, are alloys in which the atoms of one element is placed in between the spaces of the atoms of the other element. This occurs when one metal’s atoms are smaller than the atoms of the other metal. An example of interstitial alloys is steel, which is a combination of iron and carbon.
Fig 3. Interstitial alloy.
Examples of alloys and their uses are listed below.
Table 9.1. Various types and uses of alloys. Alloy Combination of metal Uses
Bronze Copper and aluminum Used in sculptures, musical instruments, and
medals
automobiles and appliances
Brass Copper and zinc Used in plumbing, musical instruments, and
home furnitures
Amalgam Mercury and silver Used in electrolytic cells, extraction of gold, and dentistry (cavity filler)
Pewter Tin and antimony Used in decoration, jewelry, and tableware
Solder Tin and lead Used in connecting electronic parts and
plumbing
Metallic bonding is formed when metal atoms free their valence electrons, producing a sea of electrons which they can all share.
Alloys are solid homogeneous mixtures of metals formed by mixing two different metals together.
Substitutional alloys are alloys in which the atoms of one element substitute for the atoms of the other element in the alloy.
Check Your Understanding
A. Write true if the statement is true. Otherwise, write false.
4. Metallic bonding between atoms occur because of valence shell overlap between multiple atoms.
5. Metallic bonding allows inner core electrons, as well as valence electrons, to freely move about.
B. Assess whether the following sentences describe a substitutional or an
interstitial alloy. Write S if the sentence describes a substitutional alloy. Write I if the sentence describes an interstitial alloy. Write A if the sentence describes both alloy type. Write N if it doesn’t describe an alloy.
1. A piece of solid is made up of positively-charged copper and negatively- charged chlorine.
2. Alloys modify properties of the original metal, enhancing both strength and conductivity,
3. Brass is an example of this alloy. 4. This type of alloy is made up of atoms with relatively similar sizes. 5. These are solid, homogeneous mixtures of metals. 6. The positively-charged ion is surrounded by negatively-charged ions in
almost all directions. 7. The electrons are collectively shared between iron and carbon. 8. Multiple bonds are formed to satisfy the octet between two rhenium atoms. 9. The protons are moving from one position to another in this type of alloy. 10.Electrons are delocalized between two metal atoms.
C. For the next few questions, refer to the figure below. Answer the next few
questions.
Answer the following questions comprehensively.
1. Steel is a compound of iron and carbon. Why do you think steel is considered an alloy, as opposed to an ionic or covalent compound?
2. Graphene, a 2D sheet of carbon atoms bonded together in a lattice, is electrically conductive, harder than steel, and has a very high melting point. Despite carbon being a nonmetal, why do you think Graphene possesses these properties?
For the following combination of metals, identify what type of alloy will be formed. You can look and compare the sizes of the ions that can form from each metals to identify the type of alloy.
3. Cu and Al 4. Hg and Ag
Objectives In this lesson, you should be able to:
explain the properties of metals in terms of the electron sea model; and
Making a Sea of Electron Materials:
5 pieces each of red and blue balls, of different sizes 5 ft. wires glue or adhesives
Learn about It
Conductivity Conductivity is the ability of a material to allow heat or electric current to easily pass through. Electricity, on the other hand, is the flow of electric charge brought by the movement of electrons. Whenever electricity or heat passes through metals, it can freely flow without much obstruction from the positive nuclei of atoms. Hence, metals and alloys are electrically and thermally conductive.
Fig 4. Cooking pans are made up of metals which can transfer heat.
transfer of electricity. Electrons also carry energy while travelling which allows the transfer of heat. Density and Tensile Strength Metals are very dense, as shown in the table below. They also have high tensile strength, hence they are used as construction materials. Their high densities and high tensile strength suggest that metallic bond is very strong. This allows the atoms inside metals to pack tightly, producing rigid structures.
Table 9.2 Densities of some metals. The density of water is 1 g/cm3.
Metal Density (g/cm3)
Fig 6. High tension wires which hold the tension bridges are usually made up of
Luster
Key Points
Metals are good conductors of heat and electricity. The delocalized electrons
allows transfer of electricity, and heat is carried by the electrons as it travels from one place to another.
Metals are very dense and have high tensile strength, indicative of the immense strength of metallic bonds.
Metals have high melting and boiling points. Since metal cations are attracted to a sea of electrons, greater energy is needed to melt and boil metals.
Metals and alloys are malleable and ductile. When atoms are under stress, the delocalized electrons allow for the metal atoms to simply slide over one another without breaking the metallic bond.
Check Your Understanding
A. Write true if the statement is true. Write false otherwise.
1. Metals are ductile and malleable because cations can move about without breaking bonds.
2. Metals have high boiling points. 3. Metals can conduct electricity because electrons can freely move about the
bulk of the metal. 4. Metals do not allow electric current to flow unimpeded. 5. Metals have low melting points
B. Identify if the following physical properties describe a metal or not. Write M if it
pertains to a property of metal, and N if not. 1. Electrical wires are used to transfer electricity from a source to your
household devices. 2. Coal transfers heat to the grilled liempo. 3. Pencil lead are good conductors of electricity. 4. Metallic particles float in water. 5. Metal sheets are found in heating materials and containers. 6. Aluminum foil is used to grill bangus. 7. Diamond conducts electricity and heat. 8. Oven uses gaseous metal to transfer heat and bake cakes. 9. Tin cans can be reshaped by hammering. 10.Liquid mercury conducts electricity even in liquid form.
Answer the following questions comprehensively. 1. Differentiate a metallic bond from a covalent bond. 2. Which of the three bond types do you think is the strongest? Why? 3. Metals form metallic bonds, nonmetals form covalent bonds, and metals and
nonmetals form ionic bonds. How do you think metalloids form their bonds? 4. The conductivity of metals at very low temperatures increases to a point, that
it achieves a state called superconductivity. Based on what you know about metallic bonding, why is this so?
Properties of Metals
Objective At the end of this laboratory activity, the students should be able to:
observe properties of household metallic compounds. Materials and Equipment
stainless steel copper wire aluminum foil iron nail mossy zinc tin can charcoal hammer ziplock bags water beaker or container watch glass
Procedure Observation of Physical Properties
1. Observe the color of stainless steel, copper wire, aluminum foil, iron nail, mossy zinc, tin can and charcoal. Record your observations on the table below.
2. Similarly, observe if these solids exhibit luster. Record your observations on the table below. Put a check mark if the solid exhibits luster, and cross mark if the solid does not.
Test for Hardness and Malleability 1. Take a small amount of steel, copper wire, aluminum foil, iron nail, mossy
zinc, tin can and charcoal on separate ziplock bags. 2. Close the ziplock bags. Using a hammer, carefully pound the solids inside the
ziplock bags. Observe what happens to the solids. Continue pounding until no more changes occur.
3. Record your observations on the table below. Test for Conductivity
1. Take a small amount of steel, copper wire, aluminum foil, iron nail, mossy zinc and charcoal. Place it in separate watch glasses.
2. Using an improvised electrical conductivity set-up, test the conductivity of each solid. Touch the solids using the loose ends of the set-up. Observe if the flashlight or bulb lights up.
Waste Disposal Dispose solids in a regular trash bin. Dispose all solutions in sink with excessive amount of running water.
Data and Results (or Observation) Record your observations on the table below.
Table 1. Properties of household metals.
Household material
Exhibit luster?
Guide Questions
1. Which solids sink on water? What property is this associated with? 2. Which solids exhibit luster? Explain why these solids shine with light. 3. What can you say about the hardness of each solids? Compare it with
charcoal. 4. Which solids are malleable? Explain how can they be able to resist physical
stress. 5. Which solids are able to light up the bulb? Explain why they can light up the
bulb even at the solid state.
Performance Task
Knowing the Bond Type Your school launched a weeklong celebration called The Mystery Week. It’s an event that fosters skills development, critical thinking and creativity. The Chemistry department hosted the main activity of the week, a brain tickling puzzle about the identities of three different solids. You are part of a group of young science enthusiasts. Your group take the challenge. The Chemistry department wanted to test your chemistry skills and asked you to identify what types of bonds are present in each solids. Goal
Your task is to design a method in identifying the type of chemical bond present in each solid .
Role You are part of a group of young science enthusiasts.
Audience
Your audience is the Chemistry department. Situation
You have three different solids, labelled A, B and C. A is a thin silver sheet, while B and C are white powdery solids.
Each solids just weigh exactly 1 gram. Product/Performance and Purpose:
You will conduct a series of experiment to be able to find out what types of bonds are present in each solid.
You will explain your methods and how did you arrive to the conclusion on what type of bond each solid contains.
Standards and Criteria for Success
Your work must meet the standards found in the rubric below. Rubrics for Assessment
Criteria Below Expectations 0% to 49%
Needs Improvement 50% to 74%
Successful Performance 75 to 99%
Exemplary Performance 100%
Comprehensiveness Methods does not justify the objectives
Shows some comprehensive- ness, but most methods are not in line with the objectives
Comprehensive, some methods meet the objectives but are not planned well
Very comprehensive, method carefully planned out and techniques meet the objectives
Reliability Methods produced no data
Shows some reliability, data can be gathered but cannot be analyzed further
Reliable, data gathering and analysis offers reliable results but sometimes show inconsistencies
Shows some originality, inadequate used of resources
Original ideas, adequate use of resources
Very original, shows imaginative use of resources
After studying the unit, can you now do the following?
Check I can…
Recognize and explain properties of metals and alloys
Explain why copper can be drawn in thin wires
Reflect
Metallic compounds These are compounds made up of metals.
Delocalized electrons These are electrons which are free to move from one atom to another.
Alloys These are solid homogeneous mixtures of metals formed by mixing two different metals together.
Substitutional alloys These are substituted alloys in which the atoms of one element substitute for the atoms of the other element in the alloy.
Interstitial alloys These are substituted alloys in which the atoms of one element is placed in between the spaces of the atoms of the other element.
Sea of Electron Model This describes metals as metal cations suspended in a sea of mobile electrons. The electrons are collectively shared to satisfy octet.
Malleability It is the ability of a material to be formed into sheets without breaking apart
Clackamas Community College. “Metallic Bonding”. Accessed 3 Jul 2017. http://dl.clackamas.edu/ch104-07/metallic.htm Chang, Raymond and Kenneth A. Goldsby. 2016. Chemistry. New York, NY: McGraw-Hill Education. Silberberg, Martin. 2009. Chemistry: The Molecular Nature of Matter and Change, 5th edition. Department of Education, Republic of the Philippines. EASE II Module 14: The Chemical Bonds. 2014. Republic of the Philippines.
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