How do I draw Lewis Structure for BN and CN-
CN^- is here but you must scroll through a lot of "stuff" to get there.
http://www.kentchemistry.com/links/bonding/LewisDotTutorials/CNion.htm
I would draw BN as B:::N:
Drawing the Lewis structures for molecules or ions involves a few steps. I'll explain the process to draw the Lewis structures for BN (boron nitride) and CN- (cyanide ion).
Step 1: Calculate the total number of valence electrons.
To determine the number of valence electrons, you need to know the group number of each element.
For BN:
Boron (B) is in Group 13, so it has 3 valence electrons.
Nitrogen (N) is in Group 15, so it has 5 valence electrons.
Total valence electrons in BN: 3 (B) + 5 (N) = 8
For CN-:
Carbon (C) is in Group 14, so it has 4 valence electrons.
Nitrogen (N) is in Group 15, so it has 5 valence electrons.
The negative charge (-) indicates an extra electron.
Total valence electrons in CN-: 4 (C) + 5 (N) + 1 (charge) = 10
Step 2: Determine the central atom.
The central atom is generally the least electronegative element. In both BN and CN-, the central atom is the less electronegative atom, which is B (boron) in BN and C (carbon) in CN-.
Step 3: Connect the atoms using single bonds.
Each bond consists of two electrons, so in BN, one bond (2 electrons) will connect B and N. In CN-, a triple bond (6 electrons) will connect C and N.
Step 4: Distribute the remaining electrons on the outer atoms.
In BN, we have 8 valence electrons available. Since there is no need for additional electrons around B, all remaining electrons will be placed on N, giving nitrogen an octet. So, we place 6 lone pairs (12 electrons) around N.
In CN-, we have 10 valence electrons available. Since the carbon (C) atom has an octet already through the triple bond with N, we only need to distribute the remaining two electrons as a lone pair on the nitrogen atom.
Step 5: Check if all atoms have a complete octet.
Now, double-check to see if all atoms have a complete octet.
In BN: Boron (B) has 3 electrons (below an octet), while nitrogen (N) has 8 electrons (octet). This means B has an incomplete octet, which is acceptable for boron compounds.
In CN-: Carbon (C) has 8 electrons (octet), and nitrogen (N) has 8 electrons (octet). Both atoms have complete octets.
The Lewis structures for BN and CN- are as follows:
BN: B has a single bond with N, and N has 6 lone pairs (12 electrons).
B
|
N
CN-: C has a triple bond with N, and N has one lone pair.
C≡N
^
-
Remember, Lewis structures are a representation of electron distribution, and the goal is to achieve stability by fulfilling octet or duet rules.