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Content Benchmark P.12.A.4
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Physical Science
Matter
  P.12.A.1
  P.12.A.2
  P.12.A.3
  P.12.A.4
  P.12.A.5
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Force and Motion
Energy
Content Areas
Nature of Science (NOS)
Life Science
Earth Science
Physical Science

Students know atoms bond with one another by transferring or sharing electrons. E/S

Atoms rarely exist as independent particles in nature. Most common substances, such as the oxygen needed to breathe, the water that makes up most of the oceans and cells, and almost every other substance imaginable are made up of combinations of atoms held together by chemical bonds. A chemical bond is a mutual attraction between the nuclei and outer electrons of different atoms that binds the atoms together.

Why are most atoms bonded to each other? Most atoms that exist as independent particles are high in potential energy when compared to atoms that are bonded. The natural tendency favors arrangements in which potential energy is minimized. For example, a ball placed on a hillside tends to roll down the hill, thus minimizing its potential energy.

Atoms are composed of three major particles: protons, neutrons, and electrons. Protons are positive particles, neutrons have no electrical charge, and electrons have a negative charge. Protons and neutrons are relatively massive, and the electron has very little mass when compared to protons and neutrons. The nucleus is where the protons and neutrons are located, and the electrons are found in the electron cloud, which occupies most of the volume of the atom.

A chemical bond is a mutual attraction between nuclei and valence electrons of adjacent atoms that binds the atoms to each other. When atoms bond, their valence electrons are redistributed. The way in which the redistribution occurs determines the type of bonding. There are two main types of chemical bonding, covalent and ionic. In covalent bonding, electrons are shared between two adjacent atoms. These shared electrons are attracted by the nuclei of both atoms, forming a chemical bond that holds these atoms together. The atoms being bonded have similar attractions for the electrons that they share.

Figure 1: Different representations of the covalent bonds found in methane (natural gas) (From http://www.biology.arizona.edu
biochemistry/tutorials/chemistry/page2.html
)

In ionic bonding, electrons are transferred from one atom to another. A positive ion (cation) is formed when electron(s) are lost, and a negative ion (anion) is formed when electron(s) are gained. Now that there are positive and negative ions close to each other, there is an electrostatic attraction between these oppositely charged ions, and that attraction is the ionic bond. The atoms bonded with ionic bonds have large differences in attraction for electrons so that the electrons are transferred.

Figure 2: Ionic bonding in sodium chloride (table salt)
(from http://www.biology.arizona.edu/
biochemistry/tutorials/chemistry/page2.html
)

To learn more about bonding between atoms, go to http://web.jjay.cuny.edu/~acarpi/NSC/5-bonds.htm

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Content Benchmark P.12.A.4

Students know atoms bond with one another by transferring or sharing electrons. E/S

Common misconceptions associated with this benchmark:

1. Students incorrectly think that atoms want to transfer or share electrons to form bonds.

Atoms are not alive; they do not have wants and needs. Atoms bond because it lowers their potential energy, a tendency which is favored in nature.

To learn more about this, go to http://www.daisley.net/hellevator /misconceptions/misconceptions.pdf

2. Students incorrectly think that atoms are happy when they have an octet of electrons.

This is similar to misconception #1 in that students attribute feelings to explain why bonding occurs. Atoms bond because this lowers their potential energy, a natural tendency. To learn more about it, go to
http://www.bcpl.net/~kdrews/bonding/bonding.html#Bond

3. Students incorrectly think that bonding requires the input of energy

Bonding always releases energy because atoms are in a lower potential energy position once the bond has been formed. To learn more about this, go to http://hyperphysics.phy-astr.gsu.edu/hbase/chemical/bond.html

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Content Benchmark P.12.A.4

Students know atoms bond with one another by transferring or sharing electrons E/S

Sample Test Questions

1st Item Specification: Recognize that bonding electrons are outer electrons

Depth of Knowledge Level 1

  1. Analyze the model of an atom below.


Which of the above numbers indicates the orbit of the electrons that could bond with electrons of other atoms to make molecules?

  1. I
  2. II
  3. III
  4. IV
  1. Which of the following is true about the electrons of atoms that bond to form molecules?
    1. They are the strongest electrons in the atom.
    2. They are the largest electrons in the atom.
    3. They occupy the outermost orbit of the atom.
    4. They are the electrons closest to the nucleus.

Depth of Knowledge Level 2

  1. Lithium releases an electron to fluorine to form the compound lithium fluoride. Analyze the model of this ionic bonding shown in the diagram below.


(Click Image to Enlarge)

Which of the above electron transfers correctly models the bonding arrangement between lithium and fluorine to form lithium fluoride?

  1. I only
  2. II only
  3. III only
  4. I and II
  1. Atoms bond with each other by transferring or sharing electrons.


Identify the model above that shows the correct bonding arrangement of electrons between two hydrogen atoms to make H2.

  1. Model I
  2. Model II
  3. Model III
  4. Model IV

2nd Item Specification: Explain the difference between ionic and covalent bonding.

Depth of Knowledge Level 1

  1. Observe the picture of sodium releasing an electron to chlorine to form sodium chloride.


( From http://www.visionlearning.com/library/module_viewer.php?mid=55)

Which type of bond is formed by sodium and chlorine to form sodium chloride?

  1. Ionic bond.
  2. Covalent bond.
  3. Nuclear bond.
  4. Atomic bond.
  1. Which type of electron bond is formed when atoms share electrons?
    1. Ionic bond.
    2. Transfer bond.
    3. Covalent bond.
    4. Sharing bond.

Depth of Knowledge Level 2

  1. Which of the following statements is true about ionic and covalent bonding?
    1. Ionic bonds are formed between nonmetals and covalent bonds are formed between metals.
    2. Ionic and covalent bonds can be formed between metals and between nonmetals.
    3. Ionic bonds form between metals and nonmetals, and covalent bonds form between nonmetals.
    4. Ionic bonds and covalent bonds always contain at least one metal and one nonmetal.
  1. Observe the diagrams below showing ionic and covalent bonding.


Which of the following is true about the models above?

  1. Model I shows ionic bonding because the valence electrons are shared.
  2. Model II shows covalent bonding because the valence electrons are transferred.
  3. Model I shows covalent bonding because the valence electrons are transferred.
  4. Model II shows ionic bonding because one electron is transferred to another atom.

3rd Item Specification: Predict bond type based on relative positions on the periodic table (e.g., alkali metal and halogen, and typical organic compounds).

Depth of Knowledge Level 1

  1. Analyze the period table below and answer the question.


(Click Image to Enlarge)
(From http://www.elementsdatabase.com)

Which of the following is an example of alkali metals forming ionic bonds with nonmetals?

  1. Potassium (K) can form ionic bonds with chlorine (Cl).
  2. Potassium (K) can form ionic bonds with Sodium (Na).
  3. Oxygen (O) can form ionic bonds with carbon (C).
  4. Sodium (Na) can form an ionic bond with Helium (He).
  1. Analyze the period table below and answer the question.


(Click Image to Enlarge)
(From http://www.elementsdatabase.com)

Metals often form ionic bonds with nonmetals. Nonmetals often form covalent bonds with each other. Identify the true statement below.

  1. Sodium (Na) can form a covalent bond with Fluorine (F).
  2. Magnesium (Mg) can form an ionic bond with Chlorine (Cl).
  3. Lithium (Li) can form an ionic bond with Sodium (Na).
  4. Potassium (K) can form a covalent bond with Calcium (Ca).
  1. Organic compounds are molecular compounds that always contain carbon (C), usually hydrogen (H), and often nitrogen (N), sulfur (S) and phosphorus (P). Identify the organic compound below.
    1. Ammonia (NH3)
    2. Phosphate (PO4)
    3. Methane (CH4)
    4. Sulfur dioxide (SO2)

Depth of Knowledge Level 2

  1. Analyze the period table below and answer the question.


(Click Image to Enlarge)
(From http://www.elementsdatabase.com)

Identify the true statement below.

  1. Transition metals usually form bonds with the Noble gases.
  2. Alkaline Earth metals can form bonds with each other.
  3. Nonmetals cannot form bonds with each other.
  4. Alkali metals can form bonds with the halogens.
  1. Analyze the period table below and answer the question.


(Click Image to Enlarge)
(From http://www.elementsdatabase.com)

Covalent bonds are formed when atoms share pairs of valence electrons. Ionic bonds are formed when oppositely charged ions attract. Ions are charged atoms or molecules. Analyze the following table showing covalent and ionic bonds.

Covalent Bonds Ionic bonds
I C and O to form CO Na+ and Cl- to form NaCl
II N and O to form NO2 Li+ and l- to form LiF

The elements potassium (K) and Fluorine (F) can bond with each other, and the elements oxygen (O) and Sulfur (S) can bond with each other. Which of the following statements is true
about these bonds?

  1. K and F will form ionic bonds and O and S will form covalent bonds.
  2. K and F will form covalent bonds and O and S will form ionic bonds.
  3. K and F will form ionic or covalent bonds depending on if they are ions.
  4. K and F and O and S cannot form bonds with each other.
  1. Analyze the period table below and answer the question.


(Click Image to Enlarge)
(From http://www.elementsdatabase.com)

A sodium ion (Na+) can form an ionic bond with a chlorine ion (Cl-). A carbon (C) atom can form a covalent bond with and oxygen (O) atom. Identify the true statement below.

  1. Carbon (C) and Oxygen (O) can ionize and form an ionic bond.
  2. Oxygen (O) and chlorine (Cl) can ionize and form an ionic bond.
  3. Lithium (Li) and Chlorine (Cl) can form a covalent bond.
  4. Lithium (Li) and Chlorine (Cl) can ionize and form an ionic bond.

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Content Benchmark P.12.A.4

Students know atoms bond with one another by transferring or sharing electrons E/S

Answers to Sample Test Questions

  1. A, DOK Level 1
  2. C, DOK Level 1
  3. B, DOK Level 2
  4. B, DOK Level 2
  5. A, DOK Level 1
  6. C, DOK Level 1
  7. C, DOK Level 2
  8. D, DOK Level 1
  9. A, DOK Level 1
  10. B, DOK Level 1
  11. C, DOK Level 1
  12. D, DOK Level 2
  13. A, DOK Level 2
  14. D, DOK Level 2

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Content Benchmark P.12.A.4

Students know atoms bond with one another by transferring or sharing electrons. E/S

Intervention Strategies and Resources

The following is a list of intervention strategies and resources that will facilitate student understanding of this benchmark.

1. Chemical Bonding Flash Presentations
Vision Learning has produced “Chemical Bonding”, an explanation of ionic and covalent bonding. There are flash presentations on the reaction of sodium with chlorine and of hydrogen atoms to each other. When compounds are formed, their properties are different from the properties of the elements that formed them.

The direct link to “Chemical Bonding is http://www.visionlearning.com/library/module_viewer.php?mid=55

2. Chemical Bonding Explanation
“Chemical Bonding” is a short and simple explanation of covalent and ionic bonding. There are common examples (water and sodium chloride) of these types of bonding as well as of hydrogen bonding. There are some links on this page that show more detailed images of subatomic particles as well as atoms that are bonding.

To view this page, clink on the link below. http://www.nyu.edu/pages/mathmol/textbook/bonding.html

3. Covalent Bonds Explanation
“Covalent Bonds” is a more complex explanation of bonding and includes other types of bonding in addition to covalent and ionic. This page also gives schematic representations (Lewis dot diagrams) of what electrons are doing in covalent and ionic bonding. Metallic bonding and hydrogen bonding are also presented.

To see this website, click on:
http://hyperphysics.phy-astr.gsu.edu/hbase/chemical/bond.html#c2

4. Covalent, Ionic, and Metallic Bonding Lessons
“ Ithaca Science Zone” has produced lessons on covalent, ionic, and metallic bonding. Clicking on the link below will take you to covalent bonding, and there are links on this page to describe ionic and metallic bonding. Students can access only the pages they want to view. This is a very clear, concise site, and the graphics give an excellent presentation of what is happening when bonds are formed.

To access the site, go to
http://ithacasciencezone.com/chemzone/lessons/03bonding/mleebonding/covalent_bonds.htm

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Benchmark
Support Pages

Misconceptions:
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Sample Questions:
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Intervention Strategies & Resources:
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