CHEMISTRY COMMUNITY

tmehrazar

why is the answer in the key the most stable lewis structure for NO2, wouldn't having another double bond between N and the other O make all of its formal charges 0 hence more stable?

tmehrazar

How do we find the oxidation state for platinum in [Pt(Cl)2(NH3)2]?

tmehrazar

yes like if its a long string of atoms coming out of two sides of the central atom, you can imagine it would bend and make a chelate if a metal comes and connects each end

tmehrazar

where did that number come from, is it just something to know or is there a reason behind it?

tmehrazar

I know for sure non-metals have expanded octets so definitely not only transition metals. In the review today the TA said anything group 3 and lower can have an expanded octet so I think that's the most important thing to know.

tmehrazar

no we don't need to know names of molecules, the professor mentioned this in the last class and he said just to ignore that part of book problems, but you're talking about naming molecules right?

tmehrazar

What do you mean, like the lewis structure?

tmehrazar

sorry I'm still a little confused about this, can anyone further explain what resonance structures mean for the bond lengths

tmehrazar

got it!

tmehrazar

in part a, how do you know that in the lewis structure for ClO, Cl has one lone electron and not O? or does it not matter?

tmehrazar

i understand the problem, but how are we supposed to know the oxygens get double bonded in the lewis structures?

tmehrazar

b) write the complete lewis structure for the compound potassium phosphide

could somebody explain their work on this question please, I'm having trouble with it

tmehrazar

can someone also explain how to fully do this question!

tmehrazar

i think it'll be clearly stated in the question

tmehrazar

basically you can only give an answer with the same amount of sig figs as the number you used in your calculations with the lowest sig figs, this is because if you have a less precise number you can't report a more precise result an example is if you used 4.000(4sf) and 5.0000(5sf) in your calculati...

tmehrazar

what works for me is just doing valence electrons - nonbonding electrons - bonding electrons/2
i just try to remember the total you have is the valence, then you remove the lone electrons you used, then the bonding electrons divided by 2 because they're shared

tmehrazar

I'm not sure, but I got 1.550 x 10^-10m and I got that from (6.626x10^-34Js)/(3.818x10^-26kg)(112ms^-1)

I got 3.818x10^-26kg by multiplying 22.99g Na/1mol Na x 1mol Na/6.022x10^23 x 1kg/1000g

Not 100% I'm right though

Can anyone validate this?

tmehrazar

So although the trend is increasing from left to right and down to up for ionization energy, atoms that are stable, meaning either they have all unpaired electrons in their shells or all paired, have a higher ionization energy because when it is stable, it's harder to remove an electron meaning it h...

tmehrazar

I think phosphorus does have a higher ionization energy because when you look at the shells filled up, sulfur has one pair of electrons and phosphorus has all unpaired electrons. Either all unpaired or all paired makes it stable, so if phosphorus is all unpaired it take more energy to remove an elec...

tmehrazar

I had a different version, but I'm pretty sure the way to do this problem is: 10.0g malrotriose x 1 mol maltotriose/504.437g maltotriose x 18mol O2/1 mol maltotriose x 32g O2/1 mol O2 = 11.42g O2 each denominator for the fractions cancels out the numerator of the previous fraction, so you're left wi...

tmehrazar

got it thanks!

tmehrazar

thank you!! (: def helps

tmehrazar

5. f) How many electrons can have the quantum numbers n=3, l=1?

Why is the answer to this 6?

tmehrazar

4. a) Write an equation using words only that captures the conservation of energy in the photoelectric effect. Describe the conceptual change that arose from the photoelectric experiment and discuss how intensity plays a role. I got the equation, but how do you describe the conceptual change and how...

tmehrazar

2. Ammonia (NH3) reacts with oxygen (O2) to form air pollutant nitrogen oxide (NO) and water. Determine the theoretical yield of NO if 21.1 g NH3 is reacted with 42.2 g O2.

I missed the first part of the review session, is the answer to this 7.9g NO?

tmehrazar

For part c on homework problem M12, do we find the excess amount of reactant by subtracting the original amount of Al by the amount of Al we get when we convert Fe0 to grams of Al since FeO was the limiting reactant? If this works, are there other ways to find the excess reactant leftover?

tmehrazar

i was confused about this too, so it's just that equation?

tmehrazar

looks right to me!

tmehrazar

the 4s orbitals have lower energy than the 3d orbitals not the other way around, some things online say that s-orbitals are more penetrating than d-orbitals so i think that may be why

tmehrazar

How do you do question 4 on test 1? Writing a balanced equation for the combustion of fluorene.

tmehrazar

What is the minimum uncertainty in the speed of an electron confined to within a lead atom of diameter 350. pm? Model the atom as a one-dimensional box with a length equal to the diameter of the actual atom.

How do you do this problem i'm having some trouble?

tmehrazar

got it thanks!!

tmehrazar

thanks guys this helped! (:

tmehrazar

I think you count how many of each atom you have for the molecular formula and then simplify that by it's least common denominator.

tmehrazar

The question asks: Which of the following happens when the frequency of electromagnetic radiation decreases? Explain your reasoning. a) the speed of radiation decreases b) the wavelength of the radiation decreases c) the extent of the change in the electrical field at a given point decreases d) the ...

tmehrazar

Yes it can be used for both and it does depend on the basic units of the substance.

tmehrazar

What do you mean exactly, could you provide an example?

tmehrazar

What is the velocity of a neutron of wavelength 100.pm?

Do we have enough info to answer this question?

tmehrazar

A 1.50g of metallic tin was placed in 26.46g crucible and heated until all of the tin had reacted with the oxygen in air to form an oxide. The crucible and product together were found to weigh 28.35g. a) what is the empirical formula of the oxide? b) write the name of the oxide. I'm pretty confused ...

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