Valence electrons

[coolchix321]

How do you determine the number of valence electrons in an atom?
For example, how do you know that Boron has 6?
How do you know the exceptions for the Octet rule?

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[RogueUnicorn]

boron does not have 6. i think you really need to buckle down and hit the books if you need to ask these questions. not to be rude but it's extremely elementary.

 

[coolchix321]

Kaplan says that boron has 6
How do you determine the number of valence electrons in an atom?

 

[wanderer]

boron does not have 6. i think you really need to buckle down and hit the books if you need to ask these questions. not to be rude but it's extremely elementary.

I think what he's touching upon is that Boron has 6 in certain compounds like BF3.
OP: Atoms that don't obey the octet rule (that is they have less than an octet) are very rare. Some exceptions are BF3, AlCl3, and certain Beryllium compounds. Don't worry about them, but know they can exist and are usually very reactive.

 

[stockraider]

as far as exceptions for the octet rule go, i would memorize the once that can have greater than an octet, and the boron exception. for some reason, boron is only comfortable with 6 valence and AlCl3 gives the aluminum more than an octet. I think that's all you do need to know for the mcat. also, if you look at the periodic table, you can find this out by going to the group number for the non metals, that gives you the number of single valence electrons around an atom. for example, boron has 3 valence electrons in it because it is in group number 3, carbon has 4 since it is in group number 4, etc. now they can bond with other atoms to make an octet, but just remember, boron is only satisfied with 3 bonds to make six.

 

[sv3]

as far as exceptions for the octet rule go, i would memorize the once that can have greater than an octet, and the boron exception. for some reason, boron is only comfortable with 6 valence and AlCl3 gives the aluminum more than an octet. I think that's all you do need to know for the mcat. also, if you look at the periodic table, you can find this out by going to the group number for the non metals, that gives you the number of single valence electrons around an atom. for example, boron has 3 valence electrons in it because it is in group number 3, carbon has 4 since it is in group number 4, etc. now they can bond with other atoms to make an octet, but just remember, boron is only satisfied with 3 bonds to make six.

I think the rule is true for any element on the table....

 

[coolchix321]

What are the rules for valence electrons?
How does one determine how many valence electrons that an atom has??
I still don't understand...

 

[wanderer]

What are the rules for valence electrons?
How does one determine how many valence electrons that an atom has??
I still don't understand...

Go through your entire chemistry textbook and relearn everything if you are hung up on this. It's perhaps one of the most fundamental concepts in both organic and general chemistry, and you should certainly know it by now.

 

[coolchix321]

Can you just tell me how? Wow
I thought this was a forum for helping people...
I know chemistry... I just want to know the method for finding the number of valence electrons please
Is it that big of a deal to tell me?
and maybe answering this will help hundreds of others who want to know, as well
thanks

 

[coolchix321]

Boron has 3 valence electrons, but 6?
What??

 

[HippocratesX]

in order to tell how many valence electrons an atom has, you have to look at the GROUP number. If its in group 1 (like, Li, Na, etc) it has 1 valence electron. If its in group 2 (like Ca, Mg) it has 2 valence electrons. So how many valence electrons would oxygen have? (answer: 6. why? cuz its in group 6). How many does chlorine have? (answer: 7. why?.....u should be catching onto a trend while looking at your periodic table by now).

 

[stockraider]

Boron has 3 valence electrons, but 6?
What??

the element boron, by itself has 3 valence electrons around it, and each of those could participate in covalently bonding with other atoms to make sigma covalent bonds that will give you a total of 6 valence electrons.

by the way, what year of college are you? i don't recommend taking this test without first taking g chem and orgo classes. if it's been a long time since those classes just brush up on the material a little more and you'll be fine! don't sweat it too much!

 

[G1SG2]

Can you just tell me how? Wow
I thought this was a forum for helping people...
I know chemistry... I just want to know the method for finding the number of valence electrons please
Is it that big of a deal to tell me?
and maybe answering this will help hundreds of others who want to know, as well
thanks

Valence electrons are the outermost electrons of an atom. Except for transition metals, the number of valence electrons can be determined by looking at the group that the element is in. For example, all group 1 elements have 1 valence electron. All group 2 elements have 2 valence electrons. Group 13 (or 3A, since we skipped the transition metals) elements have 3 valence electrons. Boron is in group 3. It has 3 valence electrons. Group 14 have 4 valence electrons. Carbon is in group 4. It has 4 valence electrons and makes 4 bonds in a compound (i.e., CH4). Group 15 elements have 5 valence electrons, group 16 has 6, group 17 has 7, and group 18 (with the exception of He) has 8. Additionally, you can tell by looking at the number of electrons in the outermost shell. For example, the electron configuration of carbon is [He] 2s^2 2p^2. That's a total of 4 valence electrons. Hope this helps.

 

[RogueUnicorn]

this is ridiculous

 

[levodopa]

I googled "determining valence electrons" and got 1,240,000 results. You might want to start there.

 

[sv3]

this how u should approach all your studying (or at least incorporate what im about to say):

read up on the topic, think about it, test your grasp by doing some problems - you don't have to do 100 problems, but do a bunch. This will test your understanding and enhance retention. You learn a ton while doing them if you look at the explanations too.

then if you are still stuck, refer to external resources. When you come onto a forum, you can sometimes get more confused b/c people explain things in different ways. So use it as a last resort. As much as i like forums like these, unless you have a good foundation and have a specific question, it can be ineffecient at times and you can be more effecient on your own for the majority of things.

just my take

sv3