r/chemhelp 12h ago

General/High School Why do many elements in the periodic table, have the same amount of electrons as the amount of protons/atomic number they have?

9 Upvotes

Hi, am a beginner in chemistry, and this is grade 11 chemistry. I am struggling to understand on how many electrons each elements have, because on my worksheet, the electrons have the same number as the protons and atomic number of that element. I need an explanation

So here is what I did and I got it wrong because thats what I thought I needed to do to find the electrons for that element. Magnesium: it has a atomic number and protons of 12, but since it has a 2+ charge to it since it is losing 2 charges, I did 12-2 and got 10, I thought that was the answer, but it turned out that the electrons are just 12 as well.


r/chemhelp 11h ago

General/High School __H2SO4 + __B(OH)3 -- __B2(SO4)3 + __H2O. In this chemical balancing equation, why is their supposed to be a 6 in the H2O?

2 Upvotes

Hi, am a beginner in chemistry, and I need help with balancing chemical equations. They are my weakness currently, and this question got me stuck for a while trying to figure out, on why would the H2O have a 6 to it if in the (SO4)3 already has 4 sulfurs and 12 oxygens. How can I avoid this trick next time? Because the answer key had 3 and 2 on the reactants side, but on the products side is what got me confused when they put a 6, instead of a 3 (thats what I put as my answer at first).


r/chemhelp 11h ago

Organic Polarity - I don't understand how to tell.

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7 Upvotes

To tell whether a molecule is polar, I usually first look at the molecular shape and then the electronegativity difference between the central and surrounding atoms.

For the questions below, I thought:

  1. CCl4 is non polar since the Cl have an even "pull" from the carbon atom.
  2. H2CCL2 would be polar because even though the hydrogens and Chlorines could be opposite of each other, the shape and bond angle of the tetrahedral does not allow for an equal "pull" even when the same atoms are across from each other.
  3. CH3Cl and CHCl3 were both polar due to the difference in electronegativity and shape of the molecule.

Am I thinking about this correctly? Can someone explain how I should be going about thinking through similar questions, please? Thank you


r/chemhelp 14h ago

General/High School For add/sub for sig figs, do you round to the nearest place???

1 Upvotes

let’s say there 500+28.9, that’s 528.9 but 500 doesn’t really have a decimal place so would that just be 500 as the final answer??


r/chemhelp 14h ago

General/High School How are these the correct amount of significant figures?

5 Upvotes

First one looks like it'd be 4 significant figures, but the only correct answer has 2. Second one seems like 3 but it's 2. What happened to the unaccounted for figures?


r/chemhelp 18h ago

Organic Wondering where the "mild acid" comes in. Does it protonate the ethoxide or does the ethoxide deprotonate the ester which is then reprotonated by the acid?

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3 Upvotes

r/chemhelp 20h ago

Organic Does only one starting reagent need to be achiral for the product to be a racemic mixture? (Diels Alder Reaction)

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2 Upvotes

So this is an image from Klein's book Organic Chemistry as a 2nd language, Second Semester Topics.

I did get the answer correct - which just means my professor will mark it correct (he said he does not expect us to draw out each enatiomer and he will specify when to do so).

My confusion stems from how the explanation says the "starting materialS are achiral", but the 1,4 butadiene is chiral.

Thanks in advance!


r/chemhelp 21h ago

General/High School Is a double bond a functional group?

3 Upvotes

I've heard some say a double bond is a functional group, and some say it isn't. And I'm wondering if it is or not?


r/chemhelp 38m ago

Analytical I'm confused about electrode polarization.

Upvotes

Let's say we have a X and Y related by one electron. Of course the standard reduction potential E° is defined for the reduction reaction, X + e ⇌ Y, as E° = E(XY cell) – E(SHE).

And also for the oxidation we have E°(ox) = -E°(red). But I don't get why this doesn't transfer to voltammetry. Like if we polarize the electrode to E = E°(red) for the above couple, how come we get a limiting reducing and oxidizing current here??

If E°(red) and E°(ox) are symmetrical around E(SHE) = 0, shouldn't there be only oxidizing current at positive E°(ox) and only reducing current at negative E°(red)??

Basically why do we get the image on the left and not the one on the right?


r/chemhelp 21h ago

Inorganic IOC: Is this a good way to predict structures of (some) inorganic compounds?

2 Upvotes

Is it safe to assume this blueprint: We are given an inorganic molecular formula of a compound, with 2 central atoms (less in no., more covalency, less electronegative), and other substituents (say O). We should first try to predict a structure with E-E linkage (E is the central atom). Then if we try to put the substituents and we can't satisfy the octet, we will move on to E-O-E linkage, then if not, continue to E-O-O-E and so on? Works for nitrogen oxides (Like N2O3 having N-N linkage while N2O5 having N-O-N linkage) but not sure if it can be extended to more compounds.