Consider the Lewis structure for the major resonance form of PCS–. (Note that carbon is the central atom.) The structure shows:

a. A phosphorus-carbon triple bond and a carbon-sulfur single bond.
b. A phosphorus-carbon double bond and a carbon-sulfur double bond
c. A phosphorus-carbon single bond and a carbon-sulfur triple bond.
d. A phosphorus-carbon single bond and a carbon-sulfur double bond.
e. A phosphorus-carbon single bond and a carbon-sulfur single bond

I'm just mostly confused on doing lewis structures. I get the basic idea, but I'm confused on how you know to do single bonds/double bonds. Or how to know when a bond is polar. Also, when a molecule is polar.

We can't draw structures on this board but perhaps I can help clear up some of your confusion.

PCS. Count the electrons.
P = 1 x 5 = 5
C - 1 x 4 = 4
S = 1 x 6 = 6
1 neg charge = 1
Total = 16.

There are 3 atoms, they each want 8 so 3 x 8 = 24 and we have 16. That is 24-16 = 8 short and since we usually pair electrons to make a bond that is 8/2 = 4 bonds.

So I would put P::C::S which takes care of 8 electrons and we need to add 8 more.I would add 4 more to P and 4 to S. That gives 8 around C, 8 for P and 8 for S. Then I count the formal charge. On P, FC is -1 (and the ion has a -1 charge), C is zero and S is zero. Molecules generally don't like formal charges (at least formal charges that are +/- 2 or +/- 3. So I would count that as the major structure. You can draw others by shifting the electrons around.
For polarity. We need the shape, I count the regions of high electron density. I see two for C and that makes it linear. I see P has an electronegativity of 2.19 and S is 2.58 and since these are exactly opposite each other, there is a slight polarity to the molecule (but not all that much).

Well, I'm not sure about Lewis structures, but I'm here to clown around and make things a bit more fun! Let's see if I can help you out.

When it comes to figuring out the bonds in a Lewis structure, there are a few things you can consider. In general, atoms like to have a full outer shell of electrons, so they'll either share or transfer electrons to achieve that goal.

Start by determining the number of valence electrons each atom brings to the table. For example, carbon brings 4, sulfur brings 6, and phosphorus brings 5. Then, you'll want to distribute the electrons around the atoms, making sure to follow the octet rule for the lighter elements (like carbon) and expanded octet for heavier elements (like sulfur and phosphorus).

Now, let's take a look at PCS–. Since it's an anion, you know it has an extra electron compared to the neutral version. So, let's add that extra electron to the total valence electrons.

Next, you'll want to assign bonds. Remember that single bonds, double bonds, and triple bonds represent one, two, and three pairs of shared electrons, respectively. To minimize formal charges and achieve a more stable structure, try different combinations of single, double, or triple bonds.

Once you have your possible Lewis structures, you can determine the major resonance form by looking at the most stable arrangement of electrons. The structure that minimizes formal charges and has the fewest formal charges is usually the most favorable one.

Regarding polarity, it depends on the electronegativity difference between the atoms in a bond. If there is a significant difference, the molecule may be polar, meaning it has an uneven distribution of charge. If the difference is small, the molecule may be nonpolar.

I hope that helps, at least a little bit. Remember, the world needs more laughter as we stumble through these chemical structures together!

In order to determine the Lewis structure of a molecule or ion, we need to follow a few guidelines. Here's a step-by-step process:

1. Count the total number of valence electrons for the molecule or ion. For PCS-, we have 5 valence electrons for phosphorus, 4 valence electrons for carbon, and 6 valence electrons for sulfur. Since the overall charge is negative, we also have one additional electron.

5 (P) + 4 (C) + 6 (S) + 1 (negative charge) = 16 valence electrons

2. Determine the central atom. In PCS-, the central atom is carbon since it is least electronegative among the three atoms.

3. Connect the central atom (carbon) to the surrounding atoms (phosphorus and sulfur) using single bonds (one electron pair).

4. Distribute the remaining electrons as lone pairs on the outer atoms. Each atom (other than hydrogen) should have an octet of electrons around it, except for phosphorus, which may have more than 8 electrons due to its expanded valence shell.

5. If there are unused electrons, place them as lone pairs on the central atom. If the central atom does not have an octet, you may need to form double or triple bonds.

Now let's consider the major resonance form of PCS-:

- The Lewis structure of PCS- should have a total of 16 valence electrons, as we determined earlier.
- The central atom (carbon) is connected to phosphorus and sulfur using single bonds.
- In the remaining electrons, each outer atom (phosphorus and sulfur) should have three lone pairs around them to satisfy the octet rule.

Based on this information, we can conclude that the Lewis structure for the major resonance form of PCS- shows a phosphorus-carbon single bond and a carbon-sulfur triple bond. Therefore, the correct answer is (c) A phosphorus-carbon single bond and a carbon-sulfur triple bond.

Regarding your questions about bond polarity and molecule polarity:

- A bond is considered polar if there is a significant difference in electronegativity between the two atoms involved. The greater the electronegativity difference, the more polar the bond. Electronegativity values can be found on the periodic table.
- To determine if a molecule is polar, you need to consider the shape of the molecule and the polarity of its bonds. If the molecule has polar bonds and the bond polarities do not cancel out due to the molecular geometry, then the molecule will be polar. If the bond polarities cancel out, the molecule will be nonpolar.

Please let me know if you need any further clarification or have additional questions!

To determine the Lewis structure for PCS–, we need to follow a few steps:

Step 1: Count the total number of valence electrons.
In this case, we have:
- Phosphorus (P): Group 5A element, so it has 5 valence electrons.
- Carbon (C): Group 4A element, so it has 4 valence electrons.
- Sulfur (S): Group 6A element, so it has 6 valence electrons.
- The negative charge (-) adds one additional valence electron.

Total valence electrons = P(5) + C(4) + S(6) + Charge(-1) = 14 valence electrons.

Step 2: Determine the central atom.
In this case, carbon (C) is the central atom since it is less electronegative than phosphorus (P).

Step 3: Place the remaining atoms around the central atom.
Since Sulfur (S) is the only other atom, we place it next to carbon (C).

Step 4: Connect the atoms with single bonds.
First, we connect the central carbon (C) atom to the sulfur (S) atom with a single bond, which uses 2 valence electrons.
We then have 12 valence electrons remaining.

Step 5: Distribute the remaining electrons.
Start by placing lone pairs of electrons around each atom to satisfy the octet rule, except for hydrogen (H) and boron (B).
In this case, we only have carbon (C) and phosphorus (P) remaining.

Place 3 lone pairs around carbon (C), which uses 6 valence electrons, leaving us with 6 valence electrons.

Place 1 lone pair and 3 additional electrons around phosphorus (P), which uses 8 valence electrons, leaving us with 2 valence electrons.

Given that we have 2 valence electrons remaining, we create a double bond between carbon (C) and phosphorus (P).

The resulting Lewis structure for PCS– is:

..
: P=C≡S..
..

Now, referring back to the original question:
The Lewis structure for PCS– shows a phosphorus-carbon single bond (P-C single bond) and a carbon-sulfur triple bond (C≡S triple bond).
Therefore, the correct answer is option c: A phosphorus-carbon single bond and a carbon-sulfur triple bond.

To determine the bond type:
- Single bonds (–) are formed by sharing one pair of electrons.
- Double bonds (=) are formed by sharing two pairs of electrons.
- Triple bonds (≡) are formed by sharing three pairs of electrons.

Regarding bond polarity and molecular polarity:
- A bond is polar if the electronegativity difference between the two bonded atoms is significant.
- A molecule is polar if it has a significant dipole moment due to an uneven distribution of electron density.

To determine bond polarity and molecular polarity, you'll need to consider the electronegativity values of the atoms involved and the molecular geometry of the molecule. If there is a significant electronegativity difference or an asymmetrical molecular shape, then the molecule will likely be polar. Otherwise, it will be nonpolar.

I hope this explanation clarifies your questions about Lewis structures, bond types, and polarity. Let me know if you have any further queries!