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Consider the following structures: CH4 and NH3 Using Table 1 in the lab handout,

ID: 591886 • Letter: C

Question

Consider the following structures: CH4 and NH3 Using Table 1 in the lab handout, evaluate whether each of the following is the same or different between these compounds: Total valence electrons in the structure select an answer . Total areas of electron density around Select an answer central atom: # of areas of bonding around central Select an answer atom # of lone electron pairs on the central atom Electronic geometry of the molecule: Select an answer Molecular geometry of the molecule: | Select an answer Polarity of the molecule Select an answer Select an answer Using the table above, what is the best reason for the differences noted? OThe differences do not result from the atoms themselves but from a set of rules governing how atoms should behave. The differences result from the different central atom. The differences result from the presence of lone pairs in the structure. OThe differences result from the difference outer (non-central) atom.

Explanation / Answer

a)

CH4:

valence electrons --> C = 4, H = 1, then 4 + 4*1 = 8

electron density areas --> none, this is nonpolar

areas around central atom --> 4, each H

lone pairs --> none, all electrons are used in bonding

electronic geometry = tetrahedral

molecualr geometry --> tetrahedral

Poalrity --> nonpolar, no poles

b)

NH3:

valence electrons --> N = 5, H = 1, then 5 + 3*1 = 8

electron density areas --> Top of nitrogen, lone pairs presenceand Hydrogen (bottoms)

areas around central atom --> 4 --> 3 for H and 1 for lone pair

lone pairs --> 1 lone pair in nitrogen

electronic geometry = tetrahedral

molecualr geometry --> pyrdamidal

Poalrity --> polar, due to lone pairs