Chem Fall 2007

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I'm hoping we can make this a sticky and have a new Chem group for Fall 2007. I'm starting August 23. I'm taking Chem (of course), A&P 1, and Nutrition. Anyone else up for a Chem group?

Good Luck to us All!!:yeahthat:

Specializes in Critical Care, Surgical ICU.

Just got my first chem test back over chapter 1 & 2. Got a B!!!! I was four points away from an A. WOO HOO! :balloons:

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Congratulations to those of you whom just took your first tests and got such good grades!!!!

I just took my first one tonight. It seemed easier than the ungraded quiz she gave us last week. We'll see. I am getting an A in my lab and an A in my ethics class so far though :up:

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Hey everyone! I have a question I was hoping you all could help me with... (seems to be the going thing for me lately) :uhoh3:

Anyway... my instructor has us complete homework about every other week. I am stuck on a question for this weeks assignment that is actually a "fill-in-the-blank" so I'll try my best to explain it..

She gave us the element Isotope and then there are blanks by each isotope for protons/neutrons/and electrons. She just put the isotope information in the blank... for instance.. for Oxygen it says O-16. So I'm suppose to fill in the blanks for Protons and Neutrons (which I get and I've done).. but is it possible to know what the electrons would be without any more information?? I thought you had to know the charge of the ion to determine the electrons. She didn't give us that...and I don't want to email her unless it's absolutely necessary.

Thanks everyone for your time. Any suggestions or insight would be so appreciated!

Jennifer

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Specializes in Critical Care, Surgical ICU.

Hey Jennifer let me see if I can help you. If you have O-16 you look at the periodic table and find what the atomic number for O is, which is 8. You then subtract 8 from your isotope of 16, which leaves you with 8. So your answer is 8 protons and 8 neutrons.

Always remember your atomic number is the number of protons your element has. Always subtract the atomic number from the isotope number to get the number of protons and neutrons, and your element will always have the same number of protons and electrons. Since O has 8 protons it automatically has 8 electrons. Hope this helps you. :)

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Specializes in being a Credible Source.

What Shampagne has told you is correct.

The number of protons in an atom define the element. Oxygen always always always has 8 protons. If it had a different number of protons, it would be a different element.

The number of neutrons varies. Elements with different numbers of neutrons are known as isotopes. The most stable isotopes often have the same number of neutrons as protons but not always.

The atomic number is the number of protons and defines the element. The atomic mass is the number of protons plus the number of neutrons.

In many cases, the atomic mass is not an integer. This is because naturally occurring samples of the element often have multiple isotopes.

In a neutrally charged atom, the number of electrons will equal the number of protons. If it's an ion, there will be more or fewer electrons than protons and the charge of the ion will be thusly determined.

I am presuming that you have not yet covered electron configuration. If you have, your answer will need to include the electron configuration and not just the total number of electrons. For example, oxygen would be 1s2 2s2 2p4. If you haven't seen this yet, don't worry about it.

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I have a question. In my Chem class we are now working on Ionic Bonding. We are talking about the Octet Rule and electronic transfers. There is an example in our book that I am confused about. Here it is: The question is Show how the following atom can achieve a Noble Gas Configuraton and become an ion by gaining or losing electrons:

The answer is Na---->Na+ +1e-

What I am confused about is if the atom is losing an electron, why is it Na+ +1e- and not Na+ -1e-?????

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Hey Jennifer let me see if I can help you. If you have O-16 you look at the periodic table and find what the atomic number for O is, which is 8. You then subtract 8 from your isotope of 16, which leaves you with 8. So your answer is 8 protons and 8 neutrons.

Always remember your atomic number is the number of protons your element has. Always subtract the atomic number from the isotope number to get the number of protons and neutrons, and your element will always have the same number of protons and electrons. Since O has 8 protons it automatically has 8 electrons. Hope this helps you. :)

Thank you for your help. I guess I'm confused as to why she would have us fill in the blank without making it a little bit challenging by having the electrons a bit different??? I was worried I was missing something.

Thanks again...

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What Shampagne has told you is correct.

The number of protons in an atom define the element. Oxygen always always always has 8 protons. If it had a different number of protons, it would be a different element.

The number of neutrons varies. Elements with different numbers of neutrons are known as isotopes. The most stable elements generally have the same number of neutrons as protons but not always.

The atomic number is the number of protons and defines the element. The atomic mass is the number of protons plus the number of neutrons.

In many cases, the atomic mass is not an integer. This is because naturally occurring samples of the element often have multiple isotopes.

In a neutrally charged atom, the number of electrons will equal the number of protons. If it's an ion, there will be more or fewer electrons than protons and the charge of the ion will be thusly determined.

I am presuming that you have not yet covered electron configuration. If you have, your answer will need to include the electron configuration and not just the total number of electrons. For example, oxygen would be 1s2 2s2 2p4. If you haven't seen this yet, don't worry about it.

I'm not sure if we have covered electron config. yet?? I know we went over the different columns on the periodic table and something to do with -8?? It was the last 10 minutes of class and I think I had started day dreaming of a coffee from Starbucks by then...

Could you just explain the 1s2/2S2/2p4 for me? (if it's not too much of a bother) I just thought it was odd that she would ask us to fill in the electrons when the protons are right there and there is no "real" work involved... TIA

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Specializes in being a Credible Source.
i have a question. in my chem class we are now working on ionic bonding. we are talking about the octet rule and electronic transfers. there is an example in our book that i am confused about. here it is: the question is show how the following atom can achieve a noble gas configuraton and become an ion by gaining or losing electrons:

the answer is na---->na+ +1e-

what i am confused about is if the atom is losing an electron, why is it na+ +1e- and not na+ -1e-?????

in english, the answer is 1 sodium atom ionizes into a sodium ion plus an electron. the sodium ion has charge of +1 and the electron has a charge of -1.

this is written symbolically as na --> na+ + e- where the + simply means "and". personally, i wouldn't write the "1" in front of the e- because, as in algebra, it's understood to be a "1" unless a different coefficient is written. however, if your teacher wants you to write the "1" then you should, of course, do so.

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Specializes in being a Credible Source.
Thank you for your help. I guess I'm confused as to why she would have us fill in the blank without making it a little bit challenging by having the electrons a bit different??? I was worried I was missing something.

Thanks again...

I think she's just trying to drive home the point: In an uncharged atom, the number of electrons always equals the number of protons. ALWAYS.

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Specializes in being a Credible Source.
I'm not sure if we have covered electron config. yet?? I know we went over the different columns on the periodic table and something to do with -8?? It was the last 10 minutes of class and I think I had started day dreaming of a coffee from Starbucks by then...

Could you just explain the 1s2/2S2/2p4 for me? (if it's not too much of a bother) I just thought it was odd that she would ask us to fill in the electrons when the protons are right there and there is no "real" work involved... TIA

You'd know it if you had covered it.

I'll try to summarize very briefly. After you read about it, feel free to solicit clarification.

There are discrete levels of energy which the electrons can attain. In other words, an electron cannot have any arbitrary amount of energy but only certain discrete amounts of energy. These energy levels are simply assigned a number (1, 2, 3...)

Further, electrons are not free to be at any location around the nucleus. Rather, there are regions from which the electrons are excluded and other regions where they are more likely to be found. From quantum mechanics are found equations that yield the probability that an electron will be found at any particular location.

There are several probability functions and they have different shapes that represent the "probability cloud" around the nucleus. The electron cannot be found outside of the cloud; regions of higher cloud density correspond to a higher probability that an electron will be found there. There are a number of probability functions but the ones of interest are given the names, in increasing order of energy, s p d and f (I don't remember why, though). These are referred to as "orbitals" although the electrons don't orbit the nucleus in the sense that we typically think of orbiting bodies. There is 1 type of s orbital, 3 types of p orbitals, 5 types of d orbitals, and 7 types of f orbitals. Each of these can hold 2 electrons.

The type of orbital (s, p, d, f) possible for an electron depends on the energy level. For example, for level 1, there is only a single s orbital. For level 2, there's an s orbital and 3 p orbitals and so on up through the levels.

Since electrons always try to seek the lowest energy configuration, they start by filling the lowest level orbital (s) in the lowest energy level (1) and proceed from there.

Therefore, a hydrogen atom (1 electron) has the configuration 1s1 (one electron in the s orbital of level 1), helium (2 electrons) has the configuration 1s2 and lithium is 1s2 2s1 (2 electrons in the s orbital of level 1 and 1 in the s orbital of level 2).

This is my attempt to simplify and summarize a complex subject. I have no idea the level to which you'll be expected to learn it. I've left out a lot (both intentionally and because I'm doing this from memory) so if this just confuses you more, my apologies.

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in english, the answer is 1 sodium atom ionizes into a sodium ion plus an electron. the sodium ion has charge of +1 and the electron has a charge of -1.

this is written symbolically as na --> na+ + e- where the + simply means "and". personally, i wouldn't write the "1" in front of the e- because, as in algebra, it's understood to be a "1" unless a different coefficient is written. however, if your teacher wants you to write the "1" then you should, of course, do so.

thank you so much for answering this question. that makes more sense to me. also, i was reading your other post about the electronic configurations. i think you did an awesome job summarizng it (especially based on memory.) :up::wink2:

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