April 18, 2019, 07:18:04 PM
Forum Rules: Read This Before Posting


Topic: What is the formal charge of Carbon in H3C?  (Read 32841 times)

0 Members and 1 Guest are viewing this topic.

Immortal

  • Guest
What is the formal charge of Carbon in H3C?
« on: February 07, 2006, 01:06:18 AM »
Ok the question is "What is the formal charge of Carbon in H3C?

I did it several times and got the same answer, anyone care to try it? for those who dont know what formal charge is, the equation is :

Formal Charge = Valence Electrons - non bonding electrons - .5(bonding electrons)
« Last Edit: February 07, 2006, 02:42:11 AM by Mitch »

Offline lemonoman

  • Atmospheric
  • Chemist
  • Full Member
  • *
  • Posts: 607
  • Mole Snacks: +71/-8
  • Gender: Male
Re:What is the formal charge of Carbon in H3C?
« Reply #1 on: February 07, 2006, 03:12:15 AM »
I'm confused.  I thoughts that te CH3 'entity' could exist in three different kinds of forms (see below, correct geometry not shown):

Maybe I'm just going crazy lol :P?
« Last Edit: February 07, 2006, 03:12:47 AM by lemonoman »

Offline Mitch

  • General Chemist
  • Administrator
  • Sr. Member
  • *
  • Posts: 5260
  • Mole Snacks: +375/-2
  • Gender: Male
  • "I bring you peace." -Mr. Burns
    • Chemistry Blog
Re:What is the formal charge of Carbon in H3C?
« Reply #2 on: February 07, 2006, 03:18:11 AM »
I assume it would be the neutral.
Most Common Suggestions I Make on the Forums.
1. Start by writing a balanced chemical equation.
2. Don't confuse thermodynamic stability with chemical reactivity.
3. Forum Supports LaTex

Immortal

  • Guest
Re:What is the formal charge of Carbon in H3C?
« Reply #3 on: February 07, 2006, 01:37:28 PM »
yeah i also thought it was 0. soo.. hmm well i checked with two other fellow chem students and they also thought it was 0. and i reported it as a error(cause i take hw online) and the following reply was from a TA:
"The question asks for the formal charge of CARBON.  Carbon has 3 H's bonded to
it with single bonds and a lone pair.  Formal charge = #valence electrons -
#Lewis structure electrons.  So for carbon, there are 4 valence electrons and 5
electrons surrounding it in the Lewis structure, making the formal charge -1,
not zero.  If you need further clarification, please talk to your TA."

So i guess it the compound has 8 electrons... somehow... im not sure.. i dont think u can just give it an electron out of air >,<

Offline arnyk

  • Regular Member
  • ***
  • Posts: 54
  • Mole Snacks: +4/-3
  • Gender: Male
  • D'oh!
Re:What is the formal charge of Carbon in H3C?
« Reply #4 on: February 07, 2006, 05:30:44 PM »
Look at the middle figure in lemonoman's picture.  The carbon has 1 lone electron (the dot), giving it a formal charge of 1-.  

Offline Mitch

  • General Chemist
  • Administrator
  • Sr. Member
  • *
  • Posts: 5260
  • Mole Snacks: +375/-2
  • Gender: Male
  • "I bring you peace." -Mr. Burns
    • Chemistry Blog
Re:What is the formal charge of Carbon in H3C?
« Reply #5 on: February 07, 2006, 06:52:25 PM »
Wouldn't it be 3?
Most Common Suggestions I Make on the Forums.
1. Start by writing a balanced chemical equation.
2. Don't confuse thermodynamic stability with chemical reactivity.
3. Forum Supports LaTex

Immortal

  • Guest
Re:What is the formal charge of Carbon in H3C?
« Reply #6 on: February 08, 2006, 12:29:42 AM »
ok the actual element has two dots in it already... and i missed it... kinda didn;t expect it.. but still now its H3C:
wouldn't it have 9 electrons, only needs 8 to complete, unless this is an exception?

Offline lemonoman

  • Atmospheric
  • Chemist
  • Full Member
  • *
  • Posts: 607
  • Mole Snacks: +71/-8
  • Gender: Male
Re:What is the formal charge of Carbon in H3C?
« Reply #7 on: February 08, 2006, 09:10:03 PM »
ok the actual element has two dots in it already... and i missed it... kinda didn;t expect it.. but still now its H3C:
wouldn't it have 9 electrons, only needs 8 to complete, unless this is an exception?

H3C: has two electrons in a lone pair, and 3 bonds, each to a hydrogen.

So the formal charge on H3C: is
(Valence Electrons) - (Electrons in Lone Pairs) - (# of bonds)
= 4 - 2 - 3
= -1

This is only true for CH3 when the C has a full lone pair to itself.  CH3, the collection of four atoms, can exist together in the three ways shown in the picture above.  The three C-H bonds would exist in sp2 hybrid orbitals, and the only thing that varies is the number of electrons in the remaining 2p orbital.

CH3+ is a methyl cation...no electrons in the 2p orbital
CH3 is a neutral radical...one unpaired electron in the 2p orbital
CH3- is a methyl anion...two electrons in the 2p orbital

:) Hope that clears everything up :)

Sponsored Links