Search found 57 matches

by Lily Mohtashami
Thu Nov 19, 2020 7:37 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron configuration exceptions
Replies: 5
Views: 29

Electron configuration exceptions

Why is the electron configuration for Ni 3d10 and not 3d84s2? I thought only copper and chromium were exceptions?
Also why is Ni2+ 3d8 and not 3d64s2?
Does this mean that vanadium would be 3d5 and not 3d34s2?
by Lily Mohtashami
Wed Nov 18, 2020 11:14 pm
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: Hydrogen Bond
Replies: 5
Views: 31

Hydrogen Bond

In H2SeO4 how is there a hydrogen bond? Doesn't a hydrogen bond have to be between two O's or between two N,F, or Os? These hydrogens are just bonded to one Oxygen and nothing else!
by Lily Mohtashami
Wed Nov 18, 2020 1:49 am
Forum: Lewis Structures
Topic: Charge favorability lewis structures
Replies: 2
Views: 12

Charge favorability lewis structures

Is it more favorable for charges to be on the central atom or an outside atom?
by Lily Mohtashami
Mon Nov 16, 2020 8:07 pm
Forum: Lewis Structures
Topic: Lewis structure compounds
Replies: 1
Views: 9

Lewis structure compounds

How do you know what goes in the [] for lewis structure of compounds and what doesn't?
by Lily Mohtashami
Mon Nov 16, 2020 7:52 pm
Forum: Lewis Structures
Topic: Lewis structures
Replies: 2
Views: 26

Lewis structures

2B.9 Draw the complete Lewis structure for each of the following compounds: (a) ammonium chloride; (b) potassium phosphide; (c) sodium hypochlorite.

Can someone explain how you are supposed to know the formula for these compounds?
by Lily Mohtashami
Mon Nov 16, 2020 6:52 pm
Forum: Formal Charge and Oxidation Numbers
Topic: chemical formula of compound
Replies: 6
Views: 40

chemical formula of compound

Can someone explain how to solve this textbook problem please? 2A.23 On the basis of the expected charges on the monatomic ions, give the chemical formula of each of the following compounds: (a) magnesium arsenide; (b) indium(III) sulfide; (c) aluminum hydride; (d) hydrogen telluride; (e) bismuth(II...
by Lily Mohtashami
Sat Nov 14, 2020 3:05 pm
Forum: Trends in The Periodic Table
Topic: Textbook questions !F
Replies: 6
Views: 23

Re: Textbook questions !F

I meant 1F in the title
by Lily Mohtashami
Sat Nov 14, 2020 3:05 pm
Forum: Trends in The Periodic Table
Topic: Textbook questions !F
Replies: 6
Views: 23

Textbook questions !F

Some of the textbook questions ask to order elements in decreasing or increasing order of atomic radius and ionization energies. The answer not only orders them but also gives the exact atomic radius and ionization energies of each. Do we have to do this or do we just order them?
by Lily Mohtashami
Thu Nov 12, 2020 6:43 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron configurations
Replies: 7
Views: 27

Re: Electron configurations

Also how come Dr. Lavelle said that 4d state is lower energy than 5s state, after 2 e- have occupied 5s state. Based on what you said wouldn't it be the opposite? wouldn't it be that 4d state is lower energy than 5s state before 2 e- have occupied 5s state?
by Lily Mohtashami
Thu Nov 12, 2020 6:39 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron configurations
Replies: 7
Views: 27

Re: Electron configurations

So is the only exception that half full 3(d^5) and full 3d(d^10) have lower energy than 4s for example:
[Ar]3d^5 4s^1 and [Ar] 3d^10 4s^1
and then for everything else when you have 4s^1 it comes before 3d?
by Lily Mohtashami
Thu Nov 12, 2020 5:49 pm
Forum: Quantum Numbers and The H-Atom
Topic: Effective nuclear charge
Replies: 4
Views: 16

Re: Effective nuclear charge

Thank you so much.
by Lily Mohtashami
Thu Nov 12, 2020 5:47 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron configurations
Replies: 7
Views: 27

Electron configurations

Can someone explain exactly when electrons fills 4s state before 3d state and when they fill 3d state first?
by Lily Mohtashami
Thu Nov 12, 2020 5:00 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: e- p
Replies: 1
Views: 14

e- p

Dr. Lavelle refers to e- p a lot what does the p stand for?
by Lily Mohtashami
Thu Nov 12, 2020 4:57 pm
Forum: Quantum Numbers and The H-Atom
Topic: Effective nuclear charge
Replies: 4
Views: 16

Effective nuclear charge

Can someone explain what effective nuclear charge is?
by Lily Mohtashami
Tue Nov 10, 2020 10:31 am
Forum: Bond Lengths & Energies
Topic: Dipole
Replies: 7
Views: 19

Dipole

Can someone explain thoroughly what a dipole is? Dr. Lavelle is referring to dipole in dipole-dipole and ion-dipole bonds and I'm not sure what a dipole actually is?
by Lily Mohtashami
Mon Nov 09, 2020 2:28 pm
Forum: Ionic & Covalent Bonds
Topic: The ionic model
Replies: 7
Views: 25

Re: The ionic model

Ionic bonds have more covalent character when when the polarizing cation is distorting the polarizable anion. This happens to some extent for most ionic bonds. the farther the cation and anion are from each other on the periodic table the more distortion and covalent character they will have.
by Lily Mohtashami
Mon Nov 09, 2020 2:13 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Distortion
Replies: 8
Views: 43

Re: Distortion

distortion occurs when the cation is polarizing and attracting electrons because the ion is positive. The polarizable anion has electrons that are being pulled which forms a distorted electron cloud. The more distortion occurs the more the bond has covalent characteristics and the more soluble it wi...
by Lily Mohtashami
Mon Nov 09, 2020 2:09 pm
Forum: Sigma & Pi Bonds
Topic: Sigma and Pi bonds
Replies: 9
Views: 58

Sigma and Pi bonds

Can someone explain what a sigma bond is and what a Pi bond is? Also does anyone know which lecture we learned this in because I don't remember learning about it?
by Lily Mohtashami
Mon Nov 09, 2020 2:08 pm
Forum: Ionic & Covalent Bonds
Topic: Hydrogen Bonds [ENDORSED]
Replies: 9
Views: 50

Re: Hydrogen Bonds [ENDORSED]

Can someone please explain what a dipole dipole bond is? We learned dipole moments however I have not heard dipole in any other context until this post.
by Lily Mohtashami
Mon Nov 09, 2020 2:06 pm
Forum: Lewis Structures
Topic: Lewis Dot Structure
Replies: 11
Views: 31

Re: Lewis Dot Structure

It really depends on the certain Lewis Structure. The key is to make the structure as symmetrical as possible. So if you are making the structure for Silicon you would want one dot (electron) on each side of Si since there are four valence electrons. I think typically you would go in a clockwise ord...
by Lily Mohtashami
Mon Nov 09, 2020 2:02 pm
Forum: Resonance Structures
Topic: Bond lengths
Replies: 20
Views: 75

Re: Bond lengths

No you don't! However knowing the bond length will be important when finding the dipole moment so it is definitely good to know!
by Lily Mohtashami
Mon Nov 09, 2020 1:53 pm
Forum: Octet Exceptions
Topic: SO42- Octet Rule Exception Orbitals
Replies: 4
Views: 29

Re: SO42- Octet Rule Exception Orbitals

I believe that since 4s has lower energy than 3d it fills first but I also thought this was only true for a couple exception orbitals? Is this true for all molecules or elements?
by Lily Mohtashami
Mon Nov 09, 2020 1:44 pm
Forum: Electronegativity
Topic: Electronegativity vs. Electron Affinity
Replies: 8
Views: 34

Re: Electronegativity vs. Electron Affinity

This is a great question because electronegativity and electron affinity are very similar and have the same trends on the periodic table, however they do have slightly different definitions. Electron affinity is defined by the energy that is released when an electron attaches to the element, while e...
by Lily Mohtashami
Mon Nov 09, 2020 1:37 pm
Forum: Ionic & Covalent Bonds
Topic: delta + or -
Replies: 12
Views: 53

Re: delta + or -

We know that Oxygen is delta negative because it has a greater affinity for electrons and also a greater ionization energy which means that oxygen is also more electronegative. Oxygen will then attract more electrons which will make its overall charge more negative.

Hope this helps!
by Lily Mohtashami
Mon Nov 09, 2020 12:56 pm
Forum: Electronegativity
Topic: Delta negative and delta positive?
Replies: 8
Views: 27

Re: Delta negative and delta positive?

Hi,

yes delta negative and delta positive refer to the electronegativity of an atom. Atoms that are delta negative have a high electron affinity and ionization energy, and atoms that are delta positive will have a low electron affinity and ionization energy.
by Lily Mohtashami
Mon Nov 09, 2020 12:50 pm
Forum: Dipole Moments
Topic: Dipole clarification
Replies: 6
Views: 30

Dipole clarification

I am a little confused whether a dipole moment is calculated in a covalent or ionic bond?
by Lily Mohtashami
Wed Nov 04, 2020 10:57 am
Forum: Ionic & Covalent Bonds
Topic: SO4 covalent bond
Replies: 6
Views: 23

SO4 covalent bond

How come in lecture 14 Dr. Lavelle changes two fo the single bonds in SO4 to double bonds? Which way is the correct way to draw the structure??
by Lily Mohtashami
Sun Nov 01, 2020 5:57 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configuration
Replies: 1
Views: 17

Electron Configuration

How do you know which atoms are exceptions and don't go from 2s to 2p to 3s to 3p to 4s to 4p to 4d in order?
by Lily Mohtashami
Sun Nov 01, 2020 5:54 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Radius
Replies: 8
Views: 25

Re: Radius

Oh okay that makes sense thank you.
by Lily Mohtashami
Sun Nov 01, 2020 5:53 pm
Forum: Trends in The Periodic Table
Topic: Electron Affinity
Replies: 2
Views: 23

Electron Affinity

When finding electron affinity how do you know if energy is released or absorbed and how do you know the neutral atom and anion energy?
by Lily Mohtashami
Sun Nov 01, 2020 5:51 pm
Forum: Ionic & Covalent Bonds
Topic: Different Bonds
Replies: 8
Views: 41

Different Bonds

Can someone explain the difference in depth between an ionic and a covalent bond?
by Lily Mohtashami
Sun Nov 01, 2020 5:49 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Radius
Replies: 8
Views: 25

Radius

When ions are isoelectric how do you know which has the smallest radius?
by Lily Mohtashami
Sun Nov 01, 2020 5:47 pm
Forum: Quantum Numbers and The H-Atom
Topic: Ionization energy
Replies: 2
Views: 13

Ionization energy

Can someone explain why Oxygen has a lower first ionization energy than fluorine and nitrogen and what first ionization energy tells you?
by Lily Mohtashami
Mon Oct 26, 2020 4:42 pm
Forum: DeBroglie Equation
Topic: Diffraction Pattern
Replies: 9
Views: 57

Diffraction Pattern

Can someone explain what a diffraction pattern is exactly?
by Lily Mohtashami
Sun Oct 25, 2020 9:50 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Rydberg Equation
Replies: 2
Views: 18

Rydberg Equation

How do you know whether n is n1 or n2 in the Rydberg equation?
by Lily Mohtashami
Sun Oct 25, 2020 12:26 pm
Forum: Limiting Reactant Calculations
Topic: Midterm
Replies: 7
Views: 85

Midterm

On the midterm will the questions be like those in the textbook where it will ask for the balanced chemical equation when aluminum metal reacts with chlorine gas to produce aluminum chloride? Will we be expected to know that Chlorine gas is Cl2 or know what aluminum chloride looks like? Or will we b...
by Lily Mohtashami
Sat Oct 24, 2020 7:52 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: s and p Orbitals
Replies: 4
Views: 59

s and p Orbitals

Can someone exaplin why s is lower in energy than p in multi-electron atoms and why this isn't the case in single electron atoms?
by Lily Mohtashami
Sat Oct 24, 2020 7:44 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Orbitals
Replies: 6
Views: 66

Orbitals

How come in lecture Dr. Lavelle says when n is 2, l can be 0,1, or 2. I thought l had to be n-1 so shouldn't l only be 1 if n is 2?
by Lily Mohtashami
Fri Oct 23, 2020 5:13 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Orbitals
Replies: 9
Views: 72

Orbitals

In his lecture what does Dr. Lavelle mean when he says the 5S state?
by Lily Mohtashami
Tue Oct 20, 2020 4:30 pm
Forum: Limiting Reactant Calculations
Topic: Theoretical Yield
Replies: 12
Views: 54

Theoretical Yield

Should your theoretical yield be in moles of product or grams of product or will the question specify which it should be in?
by Lily Mohtashami
Tue Oct 20, 2020 4:18 pm
Forum: Limiting Reactant Calculations
Topic: Stoichiometric Problem
Replies: 2
Views: 15

Stoichiometric Problem

In a stoichiometric problem if the masses of each reactant are not given can you assume that the mass is 100g like you can do when finding the empirical formula, and then can you use this 100g to convert masses to moles?
by Lily Mohtashami
Sun Oct 18, 2020 8:10 pm
Forum: Properties of Electrons
Topic: Energy of photons vs electrons
Replies: 2
Views: 36

Re: Energy of photons vs electrons

I don't think the energy of a photon is necessarily half the energy of an electron. In the equation mv is also squared so there are other factors, and I think you can't really compare these equations because they are measuring different things in different scenarios.
by Lily Mohtashami
Sun Oct 18, 2020 8:06 pm
Forum: Photoelectric Effect
Topic: In a Vacuum
Replies: 7
Views: 34

Re: In a Vacuum

Using a vacuum controls the experiment so that you know anything that is observed is based completely on the light and the electrons and is not affected by any other particles. These particles could simply collide with the electrons and change the speed which alters the results of the experiment.
by Lily Mohtashami
Sun Oct 18, 2020 8:01 pm
Forum: Properties of Light
Topic: Kinetic Energy of Electron
Replies: 4
Views: 28

Re: Kinetic Energy of Electron

Another way to derive the kinetic energy is using the equation:

Ek= Ephoton- Work function
by Lily Mohtashami
Sun Oct 18, 2020 7:56 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Rydberg Equation
Replies: 1
Views: 13

Rydberg Equation

When using the Rydberg Equation how do you know which energy level is n1 or n2?
by Lily Mohtashami
Sun Oct 18, 2020 7:53 pm
Forum: Photoelectric Effect
Topic: Questions from Discussion
Replies: 2
Views: 28

Questions from Discussion

When a metal was exposed to photons at a frequency of 1.42*10^15s^-1, electrons were emitted w a maximum kinetic energy of 3.90*10^-19J. What is the maximum number of electrons that could be ejected from this metal by a burst of photons w/ a total energy of 6.22*10^-7? Can someone help explain how t...
by Lily Mohtashami
Mon Oct 12, 2020 2:30 pm
Forum: Properties of Light
Topic: Photoelectric Effect Module Questions 28 and 30
Replies: 2
Views: 52

Photoelectric Effect Module Questions 28 and 30

This is a question from the Photoelectric Effect Module. I don't understand how to do part A or C. Can someone please explain? Question: Light hits a sodium metal surface and the velocity of the ejected electron is 6.61*10^5 m.s. The work function for sodium is 150.6 KJ.mol. A. What is the kinetic e...
by Lily Mohtashami
Fri Oct 09, 2020 3:13 pm
Forum: Properties of Light
Topic: Photoelectric Effect Module Quiz
Replies: 5
Views: 68

Re: Photoelectric Effect Module Quiz

Could someone also explain how to do part c of this question? Part c asks: What is the frequency of the incident light on the sodium metal surface?
by Lily Mohtashami
Fri Oct 09, 2020 2:36 pm
Forum: Properties of Light
Topic: Photoelectric Effect Module Quiz
Replies: 5
Views: 68

Re: Photoelectric Effect Module Quiz

Can someone explain how you got the answer for part A I'm confused?
by Lily Mohtashami
Thu Oct 08, 2020 5:06 pm
Forum: SI Units, Unit Conversions
Topic: Sapling Assignment 1 Question 6
Replies: 16
Views: 114

Re: Sapling Assignment 1 Question 6

You need to make sure you convert the grams to moles so that when you dive your units will be ml=M/(M/ml) and the moles will cancel.
by Lily Mohtashami
Thu Oct 08, 2020 5:02 pm
Forum: Significant Figures
Topic: Sig Figs for Molar Mass
Replies: 14
Views: 80

Re: Sig Figs for Molar Mass

I would use four significant figures because then my answers line up with that of the textbook. Also the more decimal places you use without rounding the more accurate your number will be. Then at the end you can round to the least number of significant figures that are in the problem.
by Lily Mohtashami
Thu Oct 08, 2020 5:00 pm
Forum: Significant Figures
Topic: Sapling HW #4
Replies: 31
Views: 237

Re: Sapling HW #4

950000 has two significant figures because any zeros after integers without a decimal or number after them do not count as significant figures. 80060 has four significant figures for the same reason.
by Lily Mohtashami
Thu Oct 08, 2020 4:53 pm
Forum: Balancing Chemical Reactions
Topic: Week 1 Sapling #10 Balancing Reaction
Replies: 7
Views: 58

Re: Week 1 Sapling #10 Balancing Reaction

For this question you should pretty much disregard the bromopropane and magnesium and assume that the ratio is one to one and that the equation is already balanced. Also I was wondering do we just look up the molar mass of 2-butanone or are we expected to know it?
by Lily Mohtashami
Thu Oct 08, 2020 4:48 pm
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student [ENDORSED]
Replies: 221
Views: 115592

Re: Advice from a Medical Student [ENDORSED]

Thank you so much for your advice. It is really good to know in advice that I should keep my notes from this quarter. How do you recommend studying for tests? Would you recommend doing textbook problems or reading the textbook or rewatching lecture. What do you think is the number one thing we shoul...
by Lily Mohtashami
Thu Oct 08, 2020 4:26 pm
Forum: Empirical & Molecular Formulas
Topic: Sapling Question Number 9
Replies: 12
Views: 166

Re: Sapling Question Number 9

How did you get the molecular formula. When I find the molar mass of C6H3O2 I get 91.09 which times 2 is not equal to the Molar Mass that is given in the question. Also in the problem what does the plus or minus 10(110+_10) mean?

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