College of the Redwoods Lewis Structures Lab Report If you are able, please write down and show work so I can do the same, especially if it’s not easy to d

College of the Redwoods Lewis Structures Lab Report If you are able, please write down and show work so I can do the same, especially if it’s not easy to do typing out. If there are any requirements of a lab, you can google image search and let me know. He is pretty flexible. Please let me know what questions you have.

Learning Objectives:

Learn how to determine the number of valence electrons in a molecule or polyatomic ion
Practice developing Lewis Structures
Learn the difference between molecular formulas, Lewis structures, structural formulas, and condensed formulas.

Background:

Valence electrons are the glue that holds atoms to one another. Valence electrons are outer shell electrons. Each main group element has the same number of valence electrons as the group number. Sodium, a group 1A element, has one valence electron. Chlorine, a group 7A element, has seven valence electrons. The number of valance electrons in molecules or polyatomic ions is determined as follows:

Number of Valence Electrons = (Sum of group number of each atom) – (overall charge)

The reason for subtracting the charge is as follows:
neutral molecules have zero charge so this does not affect the number of valence electrons
polyatomic cations have lost valence electrons equal to the charge so we subtract the charge
polyatomic anions have gained valence electrons equal to the amount of charge, since the charge is negative, subtraction of the negative charge results in adding electrons.
Lewis structures are comprised of terminal atoms-atoms bonded to only one other atom, and branching or central atoms-atoms bonded to two or more other atoms. Most of the Lewis structures in this assignment have only one branching atom and all of the other atoms are bonded to this atom. Common branching atoms and the number of other atoms bonded to them can be found in the textbook. Directions for making making a Lewis structure are below:
determine the number of valence electrons
Choose the central atom (the one that usually makes the most number of bonds)
Arrange the other atoms around the branching atom
Connect the terminal atoms to the branching atoms with a single bond (each bond represents two valence electrons)
Add lone pairs (nonbonding pair of electrons) each the terminal atoms, one terminal at a time, until it has a an octet of valence electrons). The exception is hydrogen, it gets no lone pairs.
Place the remaining electrons as lone pairs on the central atom.
If the central atoms does not have an octet and it is not B, Al, Be, change a lone pair from a neighbor atom to a bonding pair to the central atom. Try to choose a lone pair that ends up giving the terminal atom the number of bonds it usually makes.

Assignment:

Briefly describe how to use the electron dot symbols of main group elements to determine the number of bonds they usually make.
Briefly describe the elements that do not make an octet when bonding and give a brief explanation for their behavior.
Briefly describe the elements that can have more than an octet and briefly describe how you can tell looking a the figure that shows the number of covalent bonds main groups elements may make.
Briefly describe:
molecular formula
Lewis structure
structural formula
condensed structure (look in the index)
Draw a Lewis structure for the following molecules:
SO2
SO3
SO42-
CH2O
AlCl3
BeCl2
PH3
H2O
Ethanol the molecular formula C2H6O and contain an O-H bond.
propose a Lewis structure
Draw the structural formula
Write the condensed formula
Tetrachloroethylene, C2Cl2, is used comercially as a dry-cleaning solvent.
Propose a Lewis structure
Draw the structural formula
Write the condensed formula
The carbonate ion contains one double bond.
Propose a Lewis structure
Draw the structural formula
Isomers of molecules have the same molecular formulas but different structures. For the isomer of ethanol:
Propose a Lewis structure
Draw the structural formula
Write the condensed formula
For coordinate covalent bonds:
What is a coordinate covalent bond? Use H+, NH3, and NH4+ to aid in your explanation.
Why is it tough to recognize (Use NH4+) to illustrate.
Why are they so important?

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