Write Lewis structures that obey the octet rule for the following species. Assign the formal cha

Write Lewis structures that obey the octet rule for the...

Key Concepts

Lewis Structures

Lewis structures are diagrams that represent the bonding between atoms of a molecule and the lone pairs of electrons that may exist in the molecule. They are useful for visualizing the arrangement of electrons based on the valence electrons of each atom, and are drawn in a way that reflects the connectivity of the atoms in the molecule.

Octet Rule

The octet rule states that atoms tend to form bonds until they are surrounded by eight valence electrons, achieving an electron configuration similar to that of the noble gases. In drawing Lewis structures, it is important to distribute electrons to ensure that each atom (with some exceptions) fulfills this condition, particularly for main group elements.

Formal Charge

Formal charge is a bookkeeping tool used in Lewis structures to estimate the distribution of electrons among atoms. It is calculated for an atom by subtracting the number of electrons assigned to it (based on lone pairs and half the bonding electrons) from its number of valence electrons. Assigning formal charges helps in determining the most stable structure by minimizing the number of charges and placing negative formal charges on the more electronegative atoms.

Counting Valence Electrons

Counting the total number of valence electrons available for bonding is a crucial step in drawing a correct Lewis structure. This includes considering the valence electrons of each atom as well as any additional electrons contributed by charges (for ions) to ensure that the electron sum is accurate before distributing them among the atoms.

Resonance Structures

Resonance structures are alternative ways of arranging electrons in a molecule that cannot be represented by a single Lewis structure. In species where electron delocalization occurs, such as polyatomic ions, multiple resonance forms can be drawn to represent the true electronic structure. Understanding resonance allows for a more complete depiction of the electron distribution which can influence properties such as reactivity and stability.

Transcript

00:01 So in problem number 99, draw the lowest structure and obey octet rule for the following species and assign the formal charge on each central atom.

00:12 So first species is p .o.

00:15 Cl3 and we know that generally less electronegative element as the central atom.

00:21 So we choose as the phosphorus, which is less electronegative.

00:25 And when we count the valence electron, so phosphorus has five.

00:30 And for oxygen is 6 and 3 chlorine atom so which 7 into 3 that mean 21 and we find out that total 32 valence electron are involved in this species so phosphores is a central atom and then we can draw the lewis structure so here oxygen and this is chlorine this is chlorine and this is chlorine like this now we can use the electrons to see the octet.

01:03 So chlorine has seven valence electrons.

01:05 So here one, two, three, four, five, six.

01:10 And similarly, here, one, two, three, four, five, six.

01:14 And one, two, three, four, five, six.

01:18 And in case of oxygen, one, two, three, four, five, six.

01:22 So basically, when we count that for each atom, that each atom that has the complete the octet, phosphosophobic.

01:31 For phosphorus that is the total 2468 and for each chlorine that is it and for oxygen it is also complete it's octet now we can also count the formal charge on each atom as by using the formula formal charge is basically the valence electron minus non -bonding electrons minus bonding electrons divided by 2.

01:59 So as we know that the phosphorus here has 8 electron completed so octet and each atom obey octets.

02:07 So that we know that the phosphorus has 5 valence electrons.

02:12 So here 4 valence are used so that the central atom has 1 positive charge.

02:23 So that the central atom has one positive charge.

02:28 So formal charge of phosphorus, we can find out that the valence electron of phosphorus is 5 and non -bonding electron is 0 and bonding electron is 8 by 2.

02:37 So which means formal charge is plus 1.

02:40 And for chlorine, we can find out that the 7 valence electron and then non -bonding electron is 6 and then bonding electron is 2 divide by 2.

02:49 So which means the chlorine as charge is equal to zero and similarly for oxygen that is six valence electron minus non -bonding electron is six and bonding two by two which means minus one so that mean the formal charge on chlorine is zero so chlorine is zero then formal charge on here it's chlorine is zero and here again zero but for oxygen formal charge is minus one so which means the overall central atom has formal charges plus 1 and it obey the octet root now we can consider the second example that is as so 4 2 minus so basically it is a sulphate and sulphur has 6 valence electron and for oxygen 6 in 2 for 24 and 2 for the negative charge so which count total 32 electrons so that mean total 32 electrons in this case and similarly 32 electron in sulphide so this structure is look like this sulphur as the central atom and then oxygen oxygen oxygen now we can use electrons 1 2 3 4 5 6 1 2 3 4 5 6 1 2 3 4 5 6 and similarly here one two three four five six so that means each atom obey its octets sulfur away octets as now formal charge we can count as the valence electron minus non -bonding electrons minus bonding electrons divide by two so that the sulfur has six valence electron as we know that it's belong to oxygen family and two electrons are short in this case so that the sulfur has formal charge that is plus 2 plus 2 and in other words we can find out the formal charge on sulfur valence electron sulfur is 6 non -bonding electron is 0 then bonding electron is 2 4 6 8 so 8 by 2 so which means 6 minus 4 which is plus 2 and we can also find out this formal charge on oxygen so 6 valence electron in oxygen non -bonding electron is 6 and bonding electron is 2 divided by 2 so which means minus 1 so that mean for each oxygen atom the charge is minus 1 minus 1 minus 1 and minus 1 so which means that the overall that is the charge on this species is 2 minus so that now we can see that the formal charge on central sulfur atom is plus 2 and each oxygen is minus 1 now we can see another example that is the next case that is c -l -o -4 minus.

06:00 So chlorine has 7 valence electron and for oxygen for each oxygen 6 valence electrons so 6 into 424 and 1 electron for a negative charge so which means that total 32 electrons are involved in this case also.

06:16 So this is chlorine and then 4 oxygen like 1, 2, 3, 3, 3.

06:23 Now we can use electron so here one two three four five six and one two three four five six one two three four five six one two three four five six now we can see that the chlorine has seven valence electron and here four valence are used and so three so three are short so that mean formal charge on chlorine is basically plus three and we can also count the formal charge so the formal charge so formal charge on chlorine is formal charge on chlorine is so valence electron that is 7 minus non -bonding electron is 0 and bonding electron 2 4 6 8 so 8 by 2 so which means 7 minus which means plus 3 formal charge on chlorine and similarly formal charge on oxygen atom is 6 minus so non -bonding electron is 6 minus 2 divide by 2 so which mean formal charge on each oxygen atom is minus 1 so that mean minus 1 minus 1 minus 1 so which means the overall that is the minus 1 on this species and total 32 electrons are involved in this case and for each atom in this species obey the octet rule now we can can see that the next case that is the case number d so in the case number d that is p of 4 3 minus so phosphate ion so phosphorus has 5 valence electron and oxygen for each oxygen 6 valence electrons so 6 into 4 24 and 3 for the negative ion so which means total 32 electrons are involved in this case and the structure of p o 4 3 minus is central atom is phosphorus as it is the less electron negative atom and then oxygen oxygen oxygen now we can see that i use electrons so here one two three four five six one two three four five six and one two three four five six similarly one two three four five six now we can see that the phosphorus has five valence electron and here one electrons are short so that means the phosphorus has plus one formal charge and we can also find out the formal charge on phosphorus so phosphorus has as we know that the five valence electron minus non -bonding is zero and bonding electron is two four six eight so eight by two so which means five minus four which is equal to plus one and for each oxygen atom we can find out the formal charge on oxygen atom that is 6 minus valence electron oxygen is 6 and then non -bonding electron is 2 for 6.

09:35 So 6 minus bonding 2 by 2...

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