CHEMISTRY COMMUNITY

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The way I determine whether a solution is acidic, basic, or neutral by looking at the formula and I follow theses rules: Acids= Hydrogen ion in front of solution. Ex. HNO3, Hc2H3O2, H2SO4 Base= OH attached to it so H is attached to the O. Ex. NaOH, KNO3, If it doesn’t have an H or attached to it the...

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You do not have to but Its helpful to know the latin names so it is easier to name it

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I don't think we do but just know how to calculate the pH of a strong acid and base

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(a) HF or HCl HCl is a stronger acid because its a binary acid meaning the H is attached to the element and the acid strength increases as you go from the right and down. (b )HClO or HClO2 HClO2 is stronger because there's more oxygens present. So that means it has a higher Ka value (c) HBrO2 or HCl...

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Acids strength increases as you go across the right and down and if H is attached to the element and if its not then the trend doesn’t apply. (This is for binary acids) Has to deal with atomic size For oxyacids, electronegativity is the determining factor so the trend is the opposite. The acid stren...

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It does not need a full octet since its an exception to the rule. As long as it has 2 bonds it's happy.

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The easiest way to calculate whether a molecule has radical is to find the total amount of electrons in the molecule and if it adds up to an odd number then it has a radical.

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Covalent character is a covalent bond, which is formed through sharing electrons. So in the covalent character has some ionic character because the two atoms have different electronegativity Polarizability is a measure of how more easily the electron cloud can be distorted. Polarity is the separatio...

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NaCl is an ionic bond. The way Lavelle calculated 250 k.j/mol. Is though calculating the amount of energy that exists in a bond between ions at a distance through Coulomb's law: the energy between 2 ions equals the product of two charges. So E=(2.31 x 10^-19 J.nm)(Q1Q2/r^2) Constant: (2.31 x 10^-19 ...

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In lecture, Lavelle had mentioned that the bond angle for H2O is (104.5) less than 109.5. I did not understand as to why it's less than 109.5. Can someone explain why this is?

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I believe they should be the same as long as you maximize the space when placing the bonds around the central atom.

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For both bonds, I know that they overlap one another but in different positions. Such as a for a sigma bond, 2 orbitals will overlap the ends side to side which allows them to rotate (say they lay horizontally on an x-axis). While Pi bonds overlap side to side preventing it from rotating because the...

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I may be wrong but from my understanding, if an atom is paired with a low electronegative atom the bond length would be longer because the atomic radius is larger, so it can accept more electrons. If its highly electronegative the bond should be shorter since it has a smaller radius and holds its el...

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1st: count the number of valence electrons 2nd: Make an element the central atom. The central atom should be that atom with the lowest ionization energy. 3rd: Place the electrons symmetrically around the elements 4th: Usually I check whether or not there may be octet exceptions and check if the elem...

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Any element from the 3rd row and beyond can have an expanded octet. These electrons become bonds or are symmetrically placed around the elements

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Octet exceptions: - H, Be, & B don't need a full octet, they can be incomplete bc it doesn't have 8 electrons: such as H can only hold 2 electrons. - Expanded octet: Anything from the 3rd row and beyond can have an expanded octet meaning it could hold more than 8 electrons, while anything in the...

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It generally doesn’t matter for now since we haven’t gotten into formal charge, so just put them anywhere around the element

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Its because the atomic radii decrease across a period, so the electrons are in the same shell closer to the nucleus and the increased nuclear charge attracts them closer to the center. Since its closer to the center its harder to remove an electron, and from here you can consider the octet rule wher...

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It's not that we skip 4s2, but rather its because we have to put in order of lowest energy to highest and 4s2 has a higher energy than 3d, therefore it will be []3d4s

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Say you’re given L, and to find how many electrons occupy a subshell you can use it to find the magnetic quantum number which is m1=1..0..+1. The quantum numbers divide the subshells into orbitals- s,p,d,f- and the orbitals hold the electrons. Example: To find the orbitals in a subshell with l=2, m ...

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Say you’re given L, and to find how many electrons occupy a subshell you can use it to find the magnetic quantum number which is m1=1..0..+1. The quantum numbers divide the subshells into orbitals- s,p,d,f- and the orbitals hold the electrons. Example: To find the orbitals in a subshell with l=2, m ...

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If you want to convert meters to nanometers all you have to do is take the given meter and multiply it by 1nm/10^-9 m, so that way you can cancel out the meters and are left over with nanometers.
Example:
(7.10 x 10^-7 m) x (1nm/10^-9m)

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The key difference between the Balmer and Lyman series is that the Lyman series is in the UV region, which is not visible and so starts at H ground state so n1=1 and from n2=2,3….
The Balmer series starts from an already excited H atom hence n1=2 and n2=3,4…. and is visible.

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In my preference, I find it easier to write the unit in terms of nanometers. Also If you want to convert meters to nanometers all you have to do is take the given meter and multiply it by 1nm/10^-9 m
Example:
(7.10 x 10^-7 m) x (1nm/10^-9m)

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In lecture the example of the car not having measurable wavelike properties (1.64 x 10^-38m ), Lavelle said that this number (10^-38) is very small therefore doesn’t show wavelike properties. I'm not sure though, someone correct me if I’m wrong.

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We will be given the formulas for the test, however, you will have to know how to rearrange these equations to get what you’re looking for. To remember formulas I just memorize the main formulas and try rearranging them to get my answer by using dimensional analysis, so it would be best if you know ...

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It does not have to deal with sig figs. I'm pretty sure it has to do with how you input the atomic mass, such as for Oxygen he rounded 15.9994 to 16. Since he rounded the atomic mass it could be the reason for his answer to b slightly different from yours.

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In this case, because the answer is 4.563 I think it safe to make it 4.56 since like you said the lowest sig fig is 3.

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No, you don’t have to memorize them I’m pretty we will not be asked to create compounds on the test. It will be something we get to know in class and along the way, you will be able to create the compounds.

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When it asks to predict the shape of a species, how would you visualize it? Do we need to know the names by memory?

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To know if an atom has an expanded octet, you don’t have to memorize it. All you need to know is that an element that is in the 3rd period and beyond can have an expanded octet. So say you’ve done the Lewis structure for XeF4, it has 36 valence electrons and since fluorine can’t have double bonds, b...

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For me, I find it useful to remember how they overlap such as that there's an axis and sigma lays along the axis, while pi is above/below the bond axis.

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In determining whether a molecule is polar or nonpolar, how do you know the charges of each atoms?

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Lone pair electrons occupy more space than bonding electron pairs because lone pairs are more excited than bonding electrons, therefore they repel each other in which they end up taking up more space.

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In lecture, Lavelle said it doesn't matter if the Lewis structure is not at its lowest formal charge, so if it doesn't matter since the shape will remain the same, can we leave it as is, or should we make it to the lowest formal charge?

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I don't think it matters if it looks different from the answer in the solutions manual, as long as it has the same number of valence electrons and it's correctly bonded, then you’re fine. If anything it would be resonance.

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In order to determine whether or not to make it a double or triple you would need to find its formal charge first, and from there try to minimize it through the bonds.

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When trying to minimize the formal charge, how do you know which element you should minimize first?

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Yes, typically when an atom is not stabilized the octet rule should be applied.

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Can someone clarify as to why in XeF4, you cant make a double bond, instead of having 2 lone pairs?

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For the Lewis structure of NO, it is a radical, and In class today the structure given was:
. ..
:N-O:
..

Is it possible that it can have a double bond instead of a single bond? Would this be resonance?

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Can someone clarify how to get the ground state?
For example in Lecture the ground state for scandium is, Sc: [Ar] 3d¹ 4s², but how is that 4s^2 follows after 3d^1, and why is [Ar] present in the ground state?

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How can you find how many electrons can occupy a subshell with a given value of L?

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Miya Lopez 1L wrote:When l=2, m can be -2, -1, 0, 1, 2 which corresponds to 5 orbitals.

I got this from the chart we wrote in lecture on 4/25.

Hope this helps :)

Hi, how did you get (-2,-1,0,1,2) from just l=2?

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Can someone explain to me as to how orbitals of a given shell in a hydrogen atom has the same energy regardless of the value of orbital angular momentum?

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I was hoping if anyone can clarify as to how I would go about answering this question.

#8. A mixture of argon and mercury vapor used in blue advertising signs emits light of wavelength 470nm. Calculate the energy change resulting from the emission of 1.00mol of photons at this wavelength.

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In question 1.7 in the textbook at asks, to calculate the wavelength.
My answer was 1.49x10^-10, but the correct answer is 1.5x10^10. Does anyone know if we have to round up, or can we leave it just like that?

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