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

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.
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.
Draw the structural formula corresponding to the molecular model and the Lewis structure.
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	Structural Formula:	Numbers:	Geometry & Polarity :
Molecules with only Single Bonds
Example: HOCl Valence electrons: _14_	H Cl	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.

Triple bonds: Try this:

White – Hydrogen

Black – Carbon

Green – Chlorine

Orange – Bromine

Blue – Nitrogen

Red – Oxygen

Questions:

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
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
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.

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

Data:

Molecular Formula:

Sketch:

Make sure elements are labeled

Lewis Dot Structure:

Structural Formula:

Numbers:

Geometry & Polarity :

Questions: