From the lewis structure of AlCl4- where should I place the formal charge? next to Al or Cl?
If you are talking about the ion itself, I would write it as
AlCl4^-
If you are talking about drawing the Lewis structure and counting formal charge on each atom; if you count them you will see that each Cl is zero formal charge and the Al has a formal charge of -1.
To determine the placement of formal charges in a molecule, you need to follow a set of guidelines. Here's the step-by-step process to figure out where to place the formal charge in the Lewis structure of AlCl4-:
1. Calculate the total number of valence electrons for the AlCl4- ion:
- Aluminum (Al) has 3 valence electrons.
- Chlorine (Cl) has 7 valence electrons each.
- Since AlCl4- carries a negative charge (-1), an additional electron needs to be included, making it a total of 5 + 4(7) + 1 = 32 valence electrons.
2. Determine the skeletal structure:
- Aluminum (Al) is the central atom since it is less electronegative than chlorine (Cl).
- Connect the four chlorine atoms (Cl) to the aluminum atom (Al) using single bonds.
3. Distribute the remaining valence electrons around the atoms:
- Place a lone pair of electrons on each chlorine atom (Cl) to complete their octets. This will account for 4 x 2 = 8 electrons.
- Distribute the remaining electrons around the central atom (Al). In this case, there are 32 - 8 = 24 electrons left for aluminum (Al).
4. Check if all atoms have achieved an octet (except hydrogen, which can have a duet):
- In the Lewis structure of AlCl4-, all atoms have a complete octet except for the aluminum atom (Al), which has only 6 electrons.
5. Place the remaining electrons on the central atom as lone pairs until it satisfies the octet rule:
- Add two additional lone pairs of electrons on the aluminum atom (Al). This will account for 4 + 4 = 8 more electrons, completing its octet.
After following these steps, you will find that the Lewis structure of AlCl4- contains four chlorine atoms (Cl) bonded to a central aluminum atom (Al) with two additional lone pairs of electrons on the aluminum atom.
Regarding the formal charges:
A formal charge can be calculated using the formula:
Formal Charge = Valence Electrons - Unshared Electrons - Half of the Shared Electrons.
In the Lewis structure of AlCl4-, each chlorine atom (Cl) has 7 valence electrons and no unshared electrons, resulting in a formal charge of 0 for each chlorine atom. The aluminum atom (Al) has 3 valence electrons and 8 electrons from the bonds, giving a formal charge of -1.
So, in the Lewis structure of AlCl4-, the formal charge is placed next to the aluminum atom (Al).
To determine where to place the formal charge in the Lewis structure of AlCl4-, you will need to calculate the formal charges for each atom. The formal charge is a way to evaluate the distribution of electrons in a compound and determine the most stable arrangement.
To calculate the formal charge, you can use the following formula:
Formal charge = Valence electrons - (Number of lone pair electrons + 0.5 * Number of bonding electrons)
For AlCl4-, Aluminum (Al) has 3 valence electrons, and each Chlorine (Cl) atom has 7 valence electrons.
Let's go step-by-step to calculate the formal charge for each atom:
1. Aluminum (Al):
Valence electrons = 3
Number of lone pair electrons = 0 (Aluminum doesn't have any lone pairs)
Number of bonding electrons = 4 (Aluminum forms four bonds with Chlorine atoms)
Formal charge (Al) = Valence electrons - (Number of lone pair electrons + 0.5 * Number of bonding electrons)
Formal charge (Al) = 3 - (0 + 0.5 * 4)
Formal charge (Al) = 3 - 2
Formal charge (Al) = +1
2. Chlorine (Cl):
Valence electrons = 7
Number of lone pair electrons = 0 (Chlorine doesn't have any lone pairs)
Number of bonding electrons = 1 (Chlorine forms one bond with Aluminum)
Formal charge (Cl) = Valence electrons - (Number of lone pair electrons + 0.5 * Number of bonding electrons)
Formal charge (Cl) = 7 - (0 + 0.5 * 1)
Formal charge (Cl) = 7 - 0.5
Formal charge (Cl) = +6.5
Based on the formal charge calculations, the formal charge of Aluminum (Al) in AlCl4- is +1, while the formal charge of each Chlorine (Cl) atom is +6.5. However, it is important to note that formal charges are not always whole numbers in some cases.
Therefore, if you are asked to place the formal charge next to Al or Cl, you would place it next to Cl since the formal charge for each Chlorine atom is +6.5.