Building Molecular Models Lab Report

Chem 1211 Central Georgia Technical College Name _______________________________________

Chemistry 1: Lab #8

Lab Group # ______________

Building Molecular Models Instructor’s initials: _____________

Purpose: To construct models of molecules containing single, double, and triple bonds: draw the structural formulas and draw the Lewis dot structures.

Equipment needed: Molecular modeling kit for each lab group.

Introduction:

Number of bonding groups attached to the central atom

Number of lone pairs on the central atom

Number of electron clouds on the central atom

Electron pair geometry

Molecular geometry

A total of only two atoms

Any number on either atom

No central atom

 

Linear

2

0

2

Linear

Linear

3

0

3

Trigonal planar

Trigonal planar

2

1

3

Trigonal planar

Bent

4

0

4

Tetrahedral

Tetrahedral

3

1

4

Tetrahedral

Trigonal Pyramidal

2

2

4

Tetrahedral

Bent

5

0

5

Trigonal Bipyramid

Trigonal Bipyramid

4

1

5

Trigonal Bipyramid

See-Saw

3

2

5

Trigonal Bipyramid

T-Shaped

2

3

5

Trigonal Bipyramid

Linear

6

0

6

Octahedral

Octahedral

5

1

6

Octahedral

Square pyramid

4

2

6

Octahedral

Square Planar

Procedure: adapted for on-line classes during the COVID-19 closure of CGTC

  1. A molecular model kit was used to build a model of each of the following molecules. Observe the picture. Sketch the model (as best you can) showing its three-dimensional structure. Notice in the example that each circle representing a ball has the symbol of the element in it.
  2. Draw the Lewis dot structure corresponding to the structural formula. Complete the octet by surrounding each atom with 8 electrons (except for hydrogen which only gets 2). The pictures of the molecular models have a wooden peg (without a wooden ball at the end) to indicate the position of a lone pair of electrons.
  3. Draw the structural formula corresponding to the molecular model and the Lewis structure.
  4. Verify each structure by identifying the number of bonds, bonding groups, lone pairs, and charge clouds on each central atom. Identify the shape & polarity of each molecule. Check electronegativity values. More electronegative = negative end of the bond. Electronegativity tells you the polarity of the bond buy you need to find the polarity of the molecule for this assignment.

Data:

Molecular Formula:

Sketch:

Make sure elements are labeled

Lewis Dot Structure:

Structural Formula:

Numbers:

Geometry & Polarity :

Molecules with only Single Bonds

Example:

HOCl

Valence electrons: _14_

H

Cl

word image 748

H – O

|

Cl

(on the O)

Bonds: _2_

Bonding Groups: _2_

Lone Pr: _2__

Clouds: __4_

Bent

Polar molecule

H2

Valence electrons: ______

   

(on either)

Bonds: ____

Bonding Groups: ____

Lone Pr: ____

Clouds: ____

 

Cl2

Valence electrons: ______

   

(on either)

Bonds: ____

Bonding Groups: ____

Lone Pr: ____

Clouds: ____

 

HBr

Valence electrons: ______

   

(on Br)

Bonds: ____

Bonding Groups: ____

Lone Pr: ____

Clouds: ____

 

CH2Cl2

Valence electrons: ______

   

(on C)

Bonds: ____

Bonding Groups: ____

Lone Pr: ____

Clouds: ____

 

N2H4

Valence electrons: ______

   

(on N)

Bonds: _____ Bonding Groups: ____

Lone Pr: ____

Clouds: ____

 

NH2OH

Valence electrons: ______

   

N central:

Bonds: _____ Bonding Groups: ____

Lone Pr: ____

Clouds: ____

O central:

Bonds: _____ Bonding Groups: ____

Lone Pr: ____

Clouds: ____

N central:

O central:

Molecules with a Double Bond

C2H4

Valence electrons: ______

   

(on C)

Bonds: _____ Bonding Groups: ____

Lone Pr: ____

Clouds: ____

 

C2H3Cl

Valence electrons: ______

   

(on C)

Bonds: _____ Bonding Groups: ____

Lone Pr: ____

Clouds: ____

 

HCOOH

Valence electrons: ______

   

C central:

Bonds: _____ Bonding Groups: ____

Lone Pr: ____

Clouds: ____

O central:

Bonds: _____ Bonding Groups: ____

Lone Pr: ____

Clouds: ____

C central:

O central

Molecules with a Triple Bond

N2

Valence electrons: ______

   

(on either)

Bonds: _____ Bonding Groups: ____

Lone Pr: ____

Clouds: ____

 

C2H2

Valence electrons: ______

   

(on C)

Bonds: _____ Bonding Groups: ____

Lone Pr: ____

Clouds: ____

 

HOCN

Valence electrons: ______

   

C central:

Bonds: _____ Bonding Groups: ____

Lone Pr: ____

Clouds: ____

O central:

Bonds: _____ Bonding Groups: ____

Lone Pr: ____

Clouds: ____

C central:

O central

Try this: (note that there are at least two possible structures)

C3H4

Valence electrons: ______

   

(for a C)

Bonds: _____ Bonding Groups: ____

Lone Pr: ____

Clouds: ____

or

Bonds: _____ Bonding Groups: ____

Lone Pr: ____

Clouds: ____

or

Bonds: _____ Bonding Groups: ____

Lone Pr: ____

Clouds: ____

 

Pictures: only Single bonds, p. 1: only Single bonds, p. 2: Double bonds:

This picture shows molecular structure for H2, Cl2 and HBr.
This picture shows molecular structure for CH2Cl2, N2H4 and NH2OH.
This picture shows molecular structure for C2H4, C2H3Cl and HCOOH.

Triple bonds: Try this:

This picture shows molecular structure for N2, C2H2 and HOCN.
This picture shows two possible molecular structures for C3H4.

White – Hydrogen

Black – Carbon

Green – Chlorine

Orange – Bromine

Blue – Nitrogen

Red – Oxygen

Questions:

  1. In your own words, define the following terms:
    1. Covalent bond
    2. Double bond
    3. Octet rule
    4. Structural formula
    5. Electron
    6. Valence electrons
  2. What do each of the following represent in the molecular model kit?
    1. A rigid connector that is not attached to an atom at one end
    2. A rigid connector with an atom at each end
    3. Two flexible connectors (springs) holding two atoms together
  3. Determine the “molecular geometry” of each of the following molecules: (the bold atom is central)
    1. H2S

___________________________________

    1. PH3

___________________________________

    1. SiH4

___________________________________

    1. CS2

___________________________________

    1. SO2

___________________________________

Seeley, Dale. Unpublished material. Central GA Technical College. 2018.

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