Covalent Bonding Day 2

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Objective

SWBAT Predict the number and types of bonds(i.e. covalent, ionic) formed based on outermost electrons and position on periodic table.

Big Idea

A little more practice and a summary to help students understand covalent bonding.

Introduction

This lesson takes place on the day where classes are shortened by 10 minutes to 40 minutes.  My lessons on these days are very streamlined and sometimes are used for summarizing and checking for student understanding.

This is the second and final day of covalent bonding where my student practice more covalent bonding and receive a summary of information that they will be tested on. 

In a traditional bonding unit, two days of practice would not be enough time to really master covalent bonding.  However, my curriculum only requires students to understand the basics of covalent bonding, such as oxygen has two bonding sites and can form a single and double bond, or nitrogen has three bonding sites and can form a single, double or triple bond. 

The main objective is that students realize that valence electrons can be shared and recognize that sharing can create an octet through covalent bonding.  Therefore, I do not have my students learn complicated covalent structures that have more than two different elements bonding.  This is all that is needed to ensure they have a foundation of simple covalent bonding to understand polarity and intermolecular forces which the next unit will address.

This lesson is aligned with NGSS HS-PS1-1, "use the periodic table as a model to predict the relative properties of elements based on the patterns of electrons in the outermost energy level of atoms" and aligned with PS1.A: The periodic table orders elements horizontally by the number of protons in the atom’s nucleus and places those with similar chemical properties in columns. The repeating patterns of this table reflect patterns of outer electron states.

This lesson continues with the Science and Engineering Practice (SEP): Developing and using models by having student use Lewis dot diagrams to illustrate how atoms such as hydrogen and oxygen can share electrons to gain an octet.

 

 

Homework/Guided Practice

10 minutes

On shortened day, I try to start class quickly by waiting for students at the door and asking them to get the previous days assignment out before the bell rings.  As they walk into the class they will see that the previous days guided practice is on the screen and can begin to check their answers on the final problems that were not completed. 

After students check these problems, we move on to the homework problems.  Before putting the assignment under the document cam I allow students about 5 minutes to work with the person next to them to either compare answers, or complete a problem or two if it wasn’t done for homework. 

As they are working the problems, I walk around looking for student work that has been completed.  I assign each of these students a problem, based on accuracy, to put on the board for the class to see.  As a reward for doing the homework (that wasn't taken for credit) I offer each of the students that comes to the board extra credit. 

After several minutes of working on problems I ask the volunteers to the board to post their answers they were assigned.  This takes several minutes, so I encourage the other students to continue to work on the problems that weren't completed.  I then take the rest of the time to go over the problems and explain the procedures that were taken in completing them.

One of the benefits of having students put their answers on the board is if there are questions the student can answer it for their classmate.  This makes me more of a facilitator, and creates a more student-centered classroom where students learn from other students.

 

Covalent Bonding Summary

20 minutes

This part of the lesson is a summary of what groups students will see covalently bond, their # of valence electrons in the group, # of bonds, example of bonded elements from that group and type of bonds formed by the group.  This takes about 15 minutes and should be written in their notes.

 


Evaluate

10 minutes

A quick way to assess their understanding is using white boards.  For the last ten minutes of class I have them use white boards to answer the following questions:

  1. What types of elements covalently bond?
  2. Draw a Lewis dot diagram for iodine?
  3. How many bonds does iodine form?
  4. Draw I2
  5. Draw NH3
  6. What group forms double bonds when bonded to the same elements
  7. Draw dot diagram for O2
  8. What group will form a triple bond when bonding to the same kind of element?
  9. Draw dot diagram for N2
  10. Draw C2H4  (this is a challenge problem that I will use for extra credit on the test)

I like ending class with a white board review because I have a set of 4 at each table and only need to handout the dry erase markers and the process of getting set up takes less than 1 minute. For this review I have each student use their own board to answer the questions because this is the last day we are working on covalent bonding and I want to know what individuals still need help.  I find the process of assessing each individual easy just by scanning the room and looking at answers as they hold their boards up.  I give them about 45 seconds to answer each one, if they finish early, I tell them to turn their board over until I ask them to hold them up.  I do this because it's easy for students to look at other answers and I want to make this as individual of an assessment as possible.

Questions 1-4 are fairly easy and I anticipate most students to get these right.  Questions 5-6 are a little more difficult, but the majority of the class should get these correct because we just reviewed double bonds. Questions 8-9 are difficult, but I am satisfied if the majority of the class can answer 8.  Since they won't have to draw a triple bond on the test; they just need to know what elements can form triple bonds and question 8 does this.  Finally, question 10 is a challenge problem and my expectation is that only a handful of kids get this one.  Again this is fine because they will not have to draw a triple bond during an assessment; it strictly was meant to provide enrichment for the more advanced students.

 Overall, I found this to be a successful formative assessment because most of the class was able to move forward.  The students that still needed help (2 or 3) I offered to come by for extra help either before or after school.  Usually a one-on-one can give these students enough help that they will be fine when it comes to the end of the unit test.