Polar covalent bond

NSCI172 Assignment: Bonding

Name ______________________________________

Complete the three activities by typing in your answer below each question, save the file as YourLastName_Bond, and upload to the dropbox. You also may handwrite and take photos of each page and upload all 7 pages to the dropbox as a pdf file using AdobeScan phone app or OneDrive phone app.

Activity 1 – A compound by any other name…

Objective: Based on the elements present in a chemical formula, classify the compound as ionic or covalent (covalent molecules are also referred to as molecular compounds).

Getting Started:

Review the definitions for an element and a compound based on the Model.

The Model:

Fe is the elemental form of iron.

C is the elemental form of carbon.

Cl2 is the elemental form of chlorine.

FeCl3 is a compound formed from the elements iron and chlorine.

Reviewing the Model

1. What does the subscript 2 indicate in Cl2?

2. What is implied when there is no subscript?

3. Classify C, Fe and Cl as metals or nonmetals.

Element	Metal or Non-metal
C
Fe
Cl

Exploring the Model

4. Based on the Model, evaluate the statement, “The formulas for elements never contain a subscript.” Is this statement true? Why or why not?

5. From the examples and the Model provided, would you expect the P₄ to represent a compound or an element? Explain your answer.

Exercising Your Knowledge

6. Classify each formula below as an element or a compound:

1. Co _______________________
2. S8 _______________________
3. CuOH _______________________
4. Br2 _______________________
5. Hg_______________________
6. Na₃N _______________________
7. BaCl2_______________________
8. Ne _______________________

Summarizing Your Thoughts

7. What clues are given in chemical formulas that allow you to differentiate between an element and a compound?

Activity 2 – Types of compounds…

Getting Started:

There are two major classes of compounds typically encountered as part of an introductory course: ionic compounds and covalent compounds. The concepts describing how these compounds are held together can be developed as you progress through your studies. However, before you get to those concepts you must be able to quickly classify a compound into one class or the other. In other words, your ability to classify compounds will guide how you will think about bigger ideas.

The Model:

Table 1 – Compounds that are considered…

Ionic	Covalent
Fe2O3	CCl4
Na2O	OF2
ZnCl2	NO2
CuI	CO

Reviewing the Model

1. The compound ZnCl2 is considered to be a (an) ______________________________ compound.

2. The compound that contains nitrogen (N) and oxygen (O) is a (an) _______________ compound

Exploring the Model

3. Does the classification seem to be based on how many atoms of each element are represented in the formula?
4. Using your mouse, place the boxes of the symbols for the elements presented by the Model (in Table 1 above) near their correct location on the outline of the periodic table. You don’t need to fill in the other empty boxes nor the entire Periodic Table. You may use your textbook.

C

I

Cu

N

O

Na

Cl

Zn

Fe

P

5. Where are the metals located in the Periodic Table? How about the non-metals? Which type of compound (ionic or covalent) contains both metals and non-metal elements?

Exercising Your Knowledge

6. Classify each of the following as either ionic or covalent compounds.

1. SiH₄____________________
2. KI ____________________
3. PH₃____________________
4. CrCl3 ____________________
5. SO2 ____________________
6. CaS ____________________
7. CO2____________________
8. AlCl3 ____________________
9. CoBr2 ____________________
10. CsF2 ____________________

Summarizing Your Thoughts

7. Write a simple rule that will allow you to classify compounds as ionic or covalent on the basis of what you have learned from the Model.

Activity 3 – Types of covalent bonds…

Getting Started:

For molecular or covalently bonded compounds, there are two types of covalent bonds: polar covalent and non-polar covalent. The difference in electronegativities of the atoms involved in the bond dictates the type.  We will focus on diatomic molecules.  Note: a table of electronegativies is on the next page.

The Model:

Table 2

Compound or Element*	Elements to be Compared	Difference in Electronegativities	*Note that H2 is an element, but the other 3 in the table are compounds.Type of Covalent Bond
HCl	H and Cl	3-2.1 = 0.9	Polar
ICl	I and Cl	3-2.5 = 0.5	Polar
HI	H and I	2.5 – 2.1 = 0.4	Non-Polar
H2	H and H	2.1-2.1 = 0	Non-Polar

Source of pictures: http://125.167.178.172/sandichem.net/chemistry/4.bp.blogspot.com/_V_sWTQG6rgE/Sq3FVdin0oI/AAAAAAAAAXE/DbvNDt-8OLU/s320/150HCL.png

Reviewing the Model.  Use the information in Table 2 and the pictures above.

1. Which of the 4 compounds or elements in Table 2 have polar covalent bonds? ______________________________________________________________
2. These have differences in electronegativies greater than a value of ___________.
3. Which of the 4 compounds or elements in Table 2 have non-polar covalent bonds? ______________________________________________________________
4. These have differences in electronegatives less than a value of _______________.
5. Which type of covalent bond has unequal sharing of electrons a large percentage of the time? polar covalent non-polar covalent
6. Which type of covalent bond has equal sharing of electrons all the time?

polar covalent                  non-polar covalent
Electronegativity Trends in the Periodic Table

Source: www.mrteverett.com/Chemistry/pdictable/electronegativity%20table.jpg

5. Fill in the blanks based on the Periodic Trend with “increases” or “decreases”:

Electronegativity _____________________________________ from left to right, and ______________________________________ from top to bottom.

Exploring the Model and Exercising your Knowledge

6. Fill in the table. The first one has been done for you.

Compound	Elements to be Compared	Difference in Electronegativities	Type of Covalent Bond
HF	H and F	4-2.1 = 1.9	Polar
HBr
Br2

7. Directions: HF is done for you so follow this example. Draw pictures for HBr and Br₂.  You may want to review the pictures on page. 4.  You don’t have to include the lone pair electrons.
8. First draw a picture of each of the compounds using a single line for a single-covalent bond. If it is contains a polar covalent bond, then indicate the location of the d+ and d- . If it is a non-polar bond, then leave out these partial charges.
9. Next draw a picture of the compound using 2 dots to represent the 2 shared electrons in the bond. If it contains a polar covalent bond, the electrons should be closest to the more electronegative atom in the bond, and you also should draw a dipole symbol.  Note: the cross in the dipole symbol is under the less electronegative atom and the point is under the more electronegative atom. If it is non-polar, then only draw the dots representing the electrons and don’t draw the dipole symbol.

Example:        a) H – F                       b) H    :F   (note that the electrons are much closer to F)

d+    d-                                          (Dipole symbol is the arrow below)

Now, do the same for HBr and Br₂ below.  You should have 4 drawings total.

Activity 4 – Review…

Directions: Below the table, there are 5 sets of 3 facts where each of the facts corresponds to one of the types of bonds.  Fill in the table using the given facts. The first set has been done for you, so you need to add the other 4 sets of facts in the remaining empty blocks in the table.

Ionic Bond	Covalent Bond
Ions	Polar	Non-Polar
Complete transfer of electron	Unequal sharing of electrons	Equal sharing of electrons

Complete transfer of electronEqual sharing of electronsUnequal sharing of electrons	Two different nonmetalsTwo identical nonmetalsMetal and nonmetal
No chargesPartial ionic chargesFull ionic charges	Electronegativity difference <0.5Electronegativity difference 0.5–1.7Electronegativity difference ˃1.7
Na+Cl–H–H·         H–F

Sources:

Activities 1 and 2 are based on Bonding_POGIL_2011 by Clutz.

Activity 3 is based on http://www.pdesas.org/module/content/resources/18006/view.ashx

Activity 4 is based on: http://www.pdesas.org/module/content/resources/18005/view.ashx and http://www.pdesas.org/module/content/resources/18006/view.ashx

Modified by Sharon Fredericks 5/22/2020.