i do not understand how to do these and i have a question on my test tomorrow on this stuff can someone explain to me how to do this?
for each of the following molecules draw the lewis structure, determine the shape, determine the polarity, and determine the kinds of intermolecular forces that are present PO4-3, HBr, CH3OH, CO2, NO2-1
Sure! I can help you with that. Let's go through each molecule step-by-step and explain how to determine the Lewis structure, shape, polarity, and intermolecular forces.
1. PO4-3:
To draw the Lewis structure, you need to follow these steps:
- Count the total number of valence electrons. In this case, there are 32 (5 from phosphorus and 6 from each oxygen atom).
- Determine the central atom. Phosphorus will be the central atom.
- Place the atoms symmetrically around the central atom, bonding each atom to the central atom with a single bond.
- Distribute the remaining electrons to satisfy the octet rule, putting extra electrons around the central atom if needed.
The Lewis structure of PO4-3 should have a double bond between one oxygen and the phosphorus atom, and three single bonds between the other oxygen atoms and the phosphorus atom.
To determine the shape:
- Count the total number of electron domains (bonded atoms and lone pairs) around the central atom. In this case, there are four electron domains around phosphorus.
- Use the VSEPR theory to determine the molecular geometry. In PO4-3, the shape is tetrahedral.
To determine the polarity:
- Check if the molecule has any polar bonds. In PO4-3, there is a polar bond between phosphorus and one of the oxygen atoms.
- Determine if the molecule has a net dipole moment. Since the polar bonds in PO4-3 are symmetrical (oxygen atoms are symmetrically positioned), the dipole moments cancel each other out, resulting in a nonpolar molecule.
To determine the intermolecular forces:
- PO4-3 does not have intermolecular forces; it is an anion and forms ionic bonds with other ions or polar molecules.
2. HBr:
To draw the Lewis structure:
- Hydrogen will be the central atom.
- Hydrogen and bromine will be connected by a single bond.
- Bromine will have a lone pair of electrons.
The Lewis structure of HBr will have one single bond and one lone pair of electrons.
To determine the shape:
- There are two electron domains around the central atom.
- The shape of HBr is linear.
To determine the polarity:
- The bond between hydrogen and bromine is polar because bromine is more electronegative.
- As there is no symmetry to cancel out the dipole moment, HBr is a polar molecule.
To determine the intermolecular forces:
- HBr has dipole-dipole interactions as the positive end of one molecule attracts the negative end of another molecule.
3. CH3OH:
To draw the Lewis structure:
- Carbon will be the central atom.
- Hydrogen and oxygen will be bonded to the carbon atom.
- Oxygen will have one lone pair of electrons.
The Lewis structure of CH3OH will have three single bonds and one lone pair of electrons.
To determine the shape:
- There are four electron domains around the central atom.
- The shape of CH3OH is tetrahedral.
To determine the polarity:
- The bond between carbon and oxygen is polar because oxygen is more electronegative.
- As there is no symmetry to cancel out the dipole moment, CH3OH is a polar molecule.
To determine the intermolecular forces:
- CH3OH has dipole-dipole interactions due to the presence of polar bonds. It can also form hydrogen bonds with other CH3OH molecules.
4. CO2:
To draw the Lewis structure:
- Carbon will be the central atom.
- Oxygen atoms will be bonded to the carbon atom.
The Lewis structure of CO2 will have a double bond between carbon and each oxygen atom.
To determine the shape:
- There are two electron domains around the central atom.
- The shape of CO2 is linear.
To determine the polarity:
- Although there are polar bonds between carbon and oxygen, the molecule is linear and symmetrical, so the bond dipoles cancel out.
- CO2 is a nonpolar molecule.
To determine the intermolecular forces:
- CO2 has London dispersion forces, as it is a nonpolar molecule.
5. NO2-1:
To draw the Lewis structure:
- Count the total number of valence electrons. Nitrogen contributes 5 electrons, each oxygen contributes 6 electrons, and the negative charge adds one extra electron. Altogether, it gives us 18 electrons.
- Nitrogen will be the central atom.
- Place the two oxygen atoms around the nitrogen atom, bonding each oxygen to the nitrogen with a single bond.
- Add the extra electron to satisfy the charge.
The Lewis structure of NO2-1 will have one double bond between nitrogen and one of the oxygen atoms, and one single bond between nitrogen and the other oxygen atom.
To determine the shape:
- There are three electron domains around the central atom.
- The shape of NO2-1 is trigonal planar.
To determine the polarity:
- The bond between nitrogen and oxygen is polar because oxygen is more electronegative.
- As there is no symmetry to cancel out the dipole moment, NO2-1 is a polar molecule.
To determine the intermolecular forces:
- NO2-1 has dipole-dipole interactions due to the presence of polar bonds.