KNO3
Draw the Lewis dot structure for KNO3. Include all nonbonding electrons. Show the formal charges of all atoms. To change the symbol of an atom, double-click on the atom and enter the letter of the new atom.
(I already tried N+, N2+, N and it was wrong…and this question want us to put the charge on each element instead of using bracket)
The correct answer and explanation is:
The molecular compound potassium nitrate (KNO₃) consists of the potassium cation (K⁺), the nitrate anion (NO₃⁻), and the associated bonds between nitrogen and oxygen atoms. To draw the Lewis structure of KNO₃, we must focus on the NO₃⁻ anion and then place the potassium ion.
Steps for drawing the Lewis structure of NO₃⁻:
- Count valence electrons:
- Nitrogen (N) is in group 15, so it has 5 valence electrons.
- Oxygen (O) is in group 16, so each oxygen atom has 6 valence electrons. There are three oxygen atoms, so 6 * 3 = 18 electrons from oxygen.
- The extra negative charge on the nitrate ion (NO₃⁻) means we add 1 more electron.
- Total valence electrons: 5 (N) + 18 (O) + 1 (charge) = 24 electrons.
- Construct the skeletal structure:
- Nitrogen is the central atom, with three oxygen atoms around it.
- Draw single bonds between nitrogen and each oxygen atom. This accounts for 6 electrons (2 electrons per bond).
- Distribute the remaining electrons:
- After placing the bonds, we have 24 – 6 = 18 electrons remaining.
- Place these 18 electrons as lone pairs around the oxygen atoms, ensuring each oxygen gets 8 electrons (two electrons in a single bond and 6 electrons in lone pairs).
- Adjust for formal charges:
- Formal charge = (Valence electrons) – (Nonbonding electrons) – (1/2 Bonding electrons)
- For nitrogen:
- Nitrogen has 5 valence electrons, 0 nonbonding electrons, and shares 6 bonding electrons (2 per bond to oxygen).
- Formal charge on nitrogen = 5 – 0 – (6/2) = 5 – 3 = +2.
- For oxygen (in a single bond):
- Each oxygen atom has 6 valence electrons, 6 nonbonding electrons, and shares 2 bonding electrons.
- Formal charge on each oxygen = 6 – 6 – (2/2) = 6 – 6 – 1 = -1.
- For oxygen (in a double bond):
- This oxygen shares 4 electrons in the double bond and has 4 nonbonding electrons.
- Formal charge = 6 – 4 – (4/2) = 6 – 4 – 2 = 0.
- Final structure:
- The nitrogen atom has a formal charge of +1, the doubly bonded oxygen has no formal charge, and the two singly bonded oxygens each have a formal charge of -1.
- This gives a net charge of -1 for the nitrate ion (NO₃⁻).
Conclusion:
The final structure of the nitrate ion (NO₃⁻) is:
- Nitrogen (N) in the center with a formal charge of +1.
- One oxygen (O) double-bonded to nitrogen with a formal charge of 0.
- Two oxygens (O) single-bonded to nitrogen, each with a formal charge of -1.
K⁺ ion: The potassium ion (K⁺) is simply a potassium atom that has lost one electron, giving it a +1 charge. It is not part of the Lewis structure for NO₃⁻ but associates with the nitrate ion to form KNO₃.
The final Lewis structure of KNO₃ is:
K⁺ [O=N-O]⁻ (O)