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C. Mark Zheng © 2008. All rights reserved. How to Draw Lewis Dot Structures (Demo)
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C. Mark Zheng © 2008. All rights reserved. How to Draw Lewis Dot Structures (Demo) Hydrogen Cyanide (HCN)
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C. Mark Zheng © 2008. All rights reserved. Step 1: Identify the central atom and draw the outer atoms around it.
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN)
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) Carbon is the central atom
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C H
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN
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C. Mark Zheng © 2008. All rights reserved. Step 2: Connect each outer atom to the central atom using a dash.
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN
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C. Mark Zheng © 2008. All rights reserved. Step 3: Count the total number of valence electrons..
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN H = 1 e -
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN H = 1 e - C = 4 e -
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN H = 1 e - C = 4 e - N = 5 e -
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN H = 1 e - C = 4 e - + N = 5 e -
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN H = 1 e - C = 4 e - + N = 5 e -
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN H = 1 e - C = 4 e - + N = 5 e - Total = 10 e -
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C. Mark Zheng © 2008. All rights reserved. Step 4: Fill each outer atom with electrons such that the outer atoms obey the octet rule.
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN Hydrogen
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN Hydrogen
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN Hydrogen 1
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN Hydrogen 1 2
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN Hydrogen full (2e - max for H) 1 2
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN Nitrogen 1 2
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN Nitrogen 1 2
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN Nitrogen 11 2
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN Nitrogen 1 2
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN Nitrogen need 6 more 1 2
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN Nitrogen 1 2 3 ●
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN Nitrogen 1 2 3 4 ●● 1 2
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN Nitrogen 1 2 3 4 5 ●● ● 1 2
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN Nitrogen 1 2 3 4 5 6 ●● ● ● 1 2
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN Nitrogen 1 2 3 4 5 6 ●● ● ● 7 ● 1 2
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN Nitrogen 1 2 3 4 5 6 ●● ● ● 8 7 ●● 1 2
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C. Mark Zheng © 2008. All rights reserved. Step 5: Apply leftover electrons to the central atom.
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN 1 2 3 4 5 6 ●● ● ● 8 7 ●● H = 1 e - C = 4 e - + N = 5 e - Total = 10 e - 1 2
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN 1 2 3 4 5 6 ●● ● ● 8 7 ●● H = 1 e - C = 4 e - + N = 5 e - Total = 10 e - used = 10 e - 1 2
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN 1 2 3 4 5 6 ●● ● ● 8 7 ●● H = 1 e - C = 4 e - + N = 5 e - Total = 10 e - - used = 10 e - 1 2
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN 1 2 3 4 5 6 ●● ● ● 8 7 ●● H = 1 e - C = 4 e - + N = 5 e - Total = 10 e - - used = 10 e - 1 2
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN 1 2 3 4 5 6 ●● ● ● 8 7 ●● H = 1 e - C = 4 e - + N = 5 e - Total = 10 e - - used = 10 e - left = 0 e - 1 2
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN 1 2 3 4 5 6 ●● ● ● 8 7 ●● H = 1 e - C = 4 e - + N = 5 e - Total = 10 e - - used = 10 e - left = 0 e - 1 2 No (zero) electron go on the central atom (C)
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C. Mark Zheng © 2008. All rights reserved. Step 6: Check each atom to see if the octet rule is obeyed.
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN 1 2 3 4 5 6 ●● ● ● 8 7 ●● 1 2
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN 1 2 3 4 5 6 ●● ● ● 8 7 ●● 1 2 We the electrons were assigned to the outer atoms, we made sure they obey the octet rule; therefore we need only check the central atom – carbon.
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN ●● ● ● ●●
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN ●● ● ● ●● 1
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN ●● ● ● ●● 1 2
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN ●● ● ● ●● 1 23
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN ●● ● ● ●● 1 23 4
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN ●● ● ● ●● 1 23 4 4
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN ●● ● ● ●● 1 23 4 4 X
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN ●● ● ● ●● 1 23 4 4 X – Does NOT obey the octet rule
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C. Mark Zheng © 2008. All rights reserved. Step 7: Move a pair of non-bonding (or lone pair) electrons from the outer atom to form a new bond with the central atom.
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN ●● ● ● ●●
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN ●● ● ● ●●
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN ●● ● ●
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C. Mark Zheng © 2008. All rights reserved. Check Octet Rule Again
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN ●● ● ● 1
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN ●● ● ● 1 2
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN ●● ● ● 1 2 3
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN ●● ● ● 1 2 3 4
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN ●● ● ● 1 2 3 4 5
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN ●● ● ● 1 2 3 4 5 6
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN ●● ● ● 1 2 3 4 5 6 6
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN ●● ● ● 1 2 3 4 5 6 6 X
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN ●● ● ● 1 2 3 4 5 6 6 X – Does NOT obey the octet rule
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN ●● ● ●
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN ●● ● ●
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN ● ●
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C. Mark Zheng © 2008. All rights reserved. Check Octet Rule Again
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN ● ●
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN ● ● 4 bonds around carbon = 8 e - + 0 lone pair e - around carbon = 0 e - valence electrons around carbon = 8 e -
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN ● ● 4 bonds around carbon = 8 e - + 0 lone pair e - around carbon = 0 e - valence electrons around carbon = 8 e - Octet rule is obeyed!
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C. Mark Zheng © 2008. All rights reserved. Step 8 & 9: Check and minimize formal charge on all atoms.
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C. Mark Zheng © 2008. All rights reserved. Step 8 & 9: Check and minimize formal charge on all atoms. F.C. = (normal # of valence e - ) – (# non-bonding e - + ½ # of bonding e - )
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN ● ●
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN ● ● AtomNormal # of Valence electrons # of non- bonding electrons # of bonding electrons Formal Charge
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN ● ● H = 1 - ( 0 + ½ (2) ) = 0 AtomNormal # of Valence electrons # of non- bonding electrons # of bonding electrons Formal Charge
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN ● ● H = 1 - ( 0 + ½ (2) ) = 0 C = 4 - ( 0 + ½ (8) ) = 0 AtomNormal # of Valence electrons # of non- bonding electrons # of bonding electrons Formal Charge
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN ● ● H = 1 - ( 0 + ½ (2) ) = 0 C = 4 - ( 0 + ½ (8) ) = 0 N = 5 - ( 2 + ½ (6) ) = 0 AtomNormal # of Valence electrons # of non- bonding electrons # of bonding electrons Formal Charge
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) C HN ● ● H = 1 - ( 0 + ½ (2) ) = 0 C = 4 - ( 0 + ½ (8) ) = 0 N = 5 - ( 2 + ½ (6) ) = 0 All Formal Charges Minimized! AtomNormal # of Valence electrons # of non- bonding electrons # of bonding electrons Formal Charge
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN)
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) Final Structure
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) Final Structure C HN ● ●
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C. Mark Zheng © 2008. All rights reserved. Hydrogen Cyanide (HCN) Final Structure C HN ● ●
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