Question

Complete the following table. Tell if the molecule is polar or nonpolar, draw the Lewis dot structure for the molecule, tell what shape the molecule is, and state what the most significant intermolecular force affecting the molecule would be.

Answer 1

The complete table is shown in figure

a) NH3 is polar as the bonds between N and H are polar. Due to asymmetry in   the molecule the molecule is polar

The shape of molecule is trigonal pyramidal while its electronic geometry is tetrahedral.

b) CO2: it is a non polar molecule with polar bonds. The molecule becomes non polar as the dipole moment cancel each other. [Dipole moment is a vector quantity]

The shape is linear.

Answer 2

Answer:

Explanation:

Ammonia: NH₃

• Polarity: nitrogen-hygrogen bond is polar because nitrogen is more electronegative than hydrogen (nitrogen atom attracts with more force to it the electrons of hydrogen), and also there is a lone pair of electrons that give the molecule a region with a negative pole. So the ammonia molecule is polar. You can see this in the attachent like ornge arrows.
• Lewis structure: check the attachment below. Nitrogen atom stays in the center position with hydrogen atoms around it. It is necesary make bonds between central atom and the surrond atoms with their valence electrons. Write the nitrogen atom in the center with all its valence electrons arround it, then do it with the hydrogen atoms, making a ile between an electron of nitrogen atom and an electron of hydrogen atom; that is a "simple bond" (a pair of bonded electrons between two atoms), remaining a pair unbonded electrons that belongs to nitrogen.
• Molecular shape: it is "trigonal pyramidal" because the central atom (nitrogen) has 3 bonds and 1 pair of non-bonded electrons. That molecular shape has the generic form AB₃E, that means, in this case, NH₃ and 1 pair of non-bonded electrons (E).

• Most significant intermolecular force: ammonia molecules interact with each other by an specific dipole-dipole intermolecular force called "Hydrogen bond". This type of intermolecular force is so strong and it takes place when an hydrogen atom interacts with lone pair electrons that belongs to a nitrogen, oxygen or fluorine atom (from another molecule).

Carbon dioxide: CO₂

• Polarity: carbon-hydrogen bond is polar because there is a difference of electronegativity between them, but the carbon dioxide molecule is nonpolar because the polarity of both bonds of carbon atom with oxygen atoms are canceled because they go in a different direction. You can see this in the attachment like orange arrows.  
• Lewis structure: check the attachment below. In thi case, Carbon atom stays in the center position with oxygen atoms each side of carbon atom. To make bonds between carbon atom and oxygen atoms correctly it is important to follow the "Octet rule", which says that atoms in a molecule tend to bond reaching 8 electrons in its valence; that's because atoms with 8 valence electrons are more stable (that's what happen with noble gases). So for  carbon atom to have 8 electrons, it is necesary to make 2 bonds with each oxygen atom, so it has 2 pair of bonded electrons. Doing this, oxygen atoms also follow the Octet rule, and all of the atoms have 8 electrons in its valence during the bonding.
• Molecular shape: it is "linear" because the central atom (carbon) has 2 bonds (even if they are double bounds they are conuted as one for the molecular shape) and no lone pair electrons. The generic form of a linear molecular shape is AB₂, which is the same as CO₂.
• Most significant intermolecular force: carbon dioxide molecules interact with each other by "London dispersion forces". These are very weak and are the only interaction between symmetric nonpolar molecules like carbon dioxide molecule.

Notes:

- Cross shape electrons and dot shape electrons are different just to differ them from each atom.

- It is very important to follow the Octet rule in the making of Lewis structure but note that not all the atoms can have 8 electrons during a bond, that's what happen with hydrogen atoms in ammonia molecule. Hydrogen atoms can have 2 electrons as maximun, because they have just 1 electron to make bonds. This also happen with elements like boron, aluminiun and others.

- Electronegative atoms must occupy the center of Lewis structure.

- Hydrogen atoms and fluorine atoms occupy terminal positions in the Lewis structure.