Search found 41 matches

by Adelpha Chan 1B
Tue Nov 19, 2019 12:11 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: seesaw
Replies: 5
Views: 19

Re: seesaw

Are the angles of a seesaw molecule 90 and 120 degrees? Or should they be slightly less than 90 and 120. The textbook answer key says it should be 90 and 120 exactly, but shouldn't the lone pair repulsion cause the angles to be slightly smaller? they should be slightly less than 90 and 120 degrees ...
by Adelpha Chan 1B
Tue Nov 19, 2019 12:10 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Pi and Sigma bonds
Replies: 5
Views: 19

Re: Pi and Sigma bonds

Can someone explain any general rules about using pi and sigma bonds? I understand how they overlap either end to end or sideways but do you have to draw out the entire 3D structure to figure this out? Or is there a rule deciding how many pi/sigma bonds are in molecules? it is a general rule that s...
by Adelpha Chan 1B
Tue Nov 19, 2019 12:09 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: How to know which angles are smaller
Replies: 8
Views: 28

Re: How to know which angles are smaller

Leila_4E wrote:Also, what are the angles of AX5E (which I think is a square pyramidal shape)?

the bond angles of an octahedral are 90. Therefore, as there is a lone pair in AX5E, the shape is a square pyramidal and the resulting bond angles are <90
by Adelpha Chan 1B
Tue Nov 19, 2019 12:08 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Linear Shape
Replies: 6
Views: 22

Re: Linear Shape

Are linear shapes always nonpolar ? are there any exceptions? linear shapes are only nonpolar if both atoms bonded to the central atom exhibit the same amount of potential energy. In the example of HCN, N exhibits a partial negative charge while H exhibits a partial positive charge as N has more el...
by Adelpha Chan 1B
Tue Nov 19, 2019 12:05 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular Shape and Structure
Replies: 1
Views: 13

Re: Molecular Shape and Structure

Could someone explain the answer to the following problem? For the following nitrogen oxide compounds: a. Draw the most stable lewis structure. b. Determine the shape. c. Determine whether the compound is polar or nonpolar. Nitric Oxide (NO) Nitrogen Dioxide (NO2) N2O Thanks! for part a, the most s...
by Adelpha Chan 1B
Tue Nov 12, 2019 12:15 pm
Forum: Empirical & Molecular Formulas
Topic: Midterm question 1
Replies: 5
Views: 34

Re: Midterm question 1

the first step to solving question 1 is to find the mass of carbon, hydrogen, nitrogen and oxygen in the final compound. The amount of carbon, hydrogen, and nitrogen are found by using dimensional analysis of the given weight of the resulting compounds in relation to mole ratios and molar mass. Add ...
by Adelpha Chan 1B
Tue Nov 12, 2019 12:09 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: central atoms
Replies: 7
Views: 26

Re: central atoms

how do you know the central atom since it's not always that with lowest ionization energy? For example, why is Cl the central atom in ClO2+ ? To allow for stability in the molecule/compound, the central atom is the atom with the lower/lowest electronegativity. In this case, oxygen is more electrone...
by Adelpha Chan 1B
Tue Nov 12, 2019 12:07 pm
Forum: Octet Exceptions
Topic: Antioxidants
Replies: 9
Views: 43

Re: Antioxidants

Isabel Day 1D wrote:How do antioxidants react with radicals? What does this look like on a chemical level?

antioxidants stabilize radicals by giving up a free electron. By stabilizing the radical, it is no longer able to attack the body and cause damage.
by Adelpha Chan 1B
Tue Nov 12, 2019 12:06 pm
Forum: Octet Exceptions
Topic: elements in 3p block
Replies: 8
Views: 66

Re: elements in 3p block

Why are Phosphorus, Chlorine, and Sulfur exceptions to the octet rule when their electron configurations do not have a 3d orbital? Is it just because they are in the third energy level? Though themselves do not normally occupy the 3d orbital, n=3 meaning that the d orbital (l=2) is available, there...
by Adelpha Chan 1B
Tue Nov 12, 2019 12:05 pm
Forum: Octet Exceptions
Topic: Limit to expanded octet
Replies: 7
Views: 47

Re: Limit to expanded octet

Aedra Li 3H wrote:Is there a certain amount of lone pairs or bonds that an expanded octet can have?

The amount of lone pairs or bonds are limited to the amount of un-bonded pairs available in the atom. The number of electrons available in the expanded octet are restricted to the capacity of the d and f orbital.
by Adelpha Chan 1B
Mon Nov 04, 2019 11:32 am
Forum: Formal Charge and Oxidation Numbers
Topic: formal charge
Replies: 5
Views: 27

Re: formal charge

When you are drawing lewis structures do you always need to solve for formal charge? Are there molecules that automatically do not have a formal charge and therefore don't need to solve the equation for? When drawing lewis structures, calculating formal charge helps you determine the best lewis str...
by Adelpha Chan 1B
Mon Nov 04, 2019 11:30 am
Forum: Ionic & Covalent Bonds
Topic: Electron Configuration
Replies: 7
Views: 33

Re: Electron Configuration

If there's a charge on an element, do we always try to move the electrons to complete an orbital or at least make it a half-filled orbital? The main goal is to lose/gain electrons in order to result in a full valence shell. The half filled orbital and s1 orbital applies only to the metals that are ...
by Adelpha Chan 1B
Mon Nov 04, 2019 11:27 am
Forum: Ionic & Covalent Bonds
Topic: Ionic vs Covalent
Replies: 14
Views: 88

Re: Ionic vs Covalent

Donavin Collins 3B wrote:How can you tell if a bond is ionic or covalent?

ionic bonds are generally between metals and nonmetals and covalent bonds are between nonmetals. However, the bond type is ultimately determined by the electronegativity difference between the two atoms.
by Adelpha Chan 1B
Mon Nov 04, 2019 11:25 am
Forum: Ionic & Covalent Bonds
Topic: Strength and Length
Replies: 18
Views: 75

Re: Strength and Length

Can someone explain the relationship between the length of the bonds and how the strength of those bonds increase or decrease accordingly? The stronger the bond, the stronger the attraction between the two atoms, resulting in a shorter bond. Vice versa, when the bond is weak, the atoms are not as c...
by Adelpha Chan 1B
Mon Nov 04, 2019 11:24 am
Forum: Administrative Questions and Class Announcements
Topic: 10/28 Updates due to Fire [ENDORSED]
Replies: 14
Views: 528

Re: 10/28 Updates due to Fire [ENDORSED]

Does anyone know if there are any workshop sessions this week (week 6)? I know there were many step-up, drop-in, and workshop sessions last week but looking for one to go to this week. Thanks Yes there are! they are all listed on the Midterm Review Sessions and Rooms link on his website (https://la...
by Adelpha Chan 1B
Mon Oct 28, 2019 11:03 am
Forum: Ionic & Covalent Bonds
Topic: Ground State
Replies: 11
Views: 51

Re: Ground State

What exactly does ground state electron configuration mean? What is it asking me to find? ground state electron configuration refers to the state of the atom where electrons are at the lowest possible energy level (no electrons are excited and jumping to higher levels). For example, the ground stat...
by Adelpha Chan 1B
Mon Oct 28, 2019 11:01 am
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Purpose of the Equation
Replies: 9
Views: 41

Re: Purpose of the Equation

So after hearing both a lecture and a discussion section about this equation, I am still incredibly confused as to what its purpose/use is. What is the purpose of this equation? The purpose of the equation is to quantify the fact that when more is known about position, less is known about speed, an...
by Adelpha Chan 1B
Mon Oct 28, 2019 10:57 am
Forum: General Science Questions
Topic: Rusty on High School Chem [ENDORSED]
Replies: 166
Views: 100974

Re: Rusty on High School Chem [ENDORSED]

Since we only have to turn in 5 answers per week, do you advise not necessarily doing all the problems listed in the syllabus and once we feel confident that we understand the material then we just make sure we have the 5 questions? Even if you are confident that you understand the material, it nev...
by Adelpha Chan 1B
Mon Oct 28, 2019 10:54 am
Forum: Limiting Reactant Calculations
Topic: Showing Work for Limiting Reactant Calculations on Tests [ENDORSED]
Replies: 66
Views: 952

Re: Showing Work for Limiting Reactant Calculations on Tests [ENDORSED]

When doing any problem, do we have to show the steps for the units? Like do we have to show how the units change in order to get the final unit? I believe you don't have to but showing all the units in your dimensional analysis helps with avoiding mistakes and allows for partial credit to be awarde...
by Adelpha Chan 1B
Mon Oct 28, 2019 10:53 am
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Test 1 [ENDORSED]
Replies: 107
Views: 1886

Re: Test 1 [ENDORSED]

I thought we were gonna be given partial credit, but my TA saw one tiny sign mistake in my problem and took away all points for that question (8 POINTS). When I asked him about it he said "you say wrong answer, you get no credit"... anyone else have this problem? Already made sure I switc...
by Adelpha Chan 1B
Tue Oct 22, 2019 3:15 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Test 1 [ENDORSED]
Replies: 107
Views: 1886

Re: Test 1 [ENDORSED]

KatherineValdez_4B wrote:Do we get the actual test back with the correct answers or just a grade?


Our TA gave us the actual test back with indications of exactly where points were lost
by Adelpha Chan 1B
Tue Oct 22, 2019 3:14 pm
Forum: Photoelectric Effect
Topic: if KE is 0 how can the electron be ejected?
Replies: 4
Views: 48

Re: if KE is 0 how can the electron be ejected?

How is the electron ejected if the energy of the photon is equal to that of the work function, meaning it has no KE? Because wouldn't it not be able to move if it has 0 KE? If there is 0 KE, it means that there was just enough energy for the electron to escape the surface of the solid metal. 0 KE r...
by Adelpha Chan 1B
Tue Oct 22, 2019 3:11 pm
Forum: Photoelectric Effect
Topic: One photon one atom interaction
Replies: 14
Views: 71

Re: One photon one atom interaction

So after the energy of light surpasses the minimum energy needed to eject an electron, would increasing the energy of light (the frequency) increase the amount of electrons ejected at that point or would the amount of electrons ejected stay the same? If the energy of each photon is enough to eject ...
by Adelpha Chan 1B
Tue Oct 22, 2019 3:10 pm
Forum: Photoelectric Effect
Topic: When energy is equal to work function
Replies: 9
Views: 73

Re: When energy is equal to work function

So in the photoelectric effect, what would happen if the energy of the photon is equal to that of the work function (ie no KINETIC ENERGY)? No additional kinetic energy means that the only output from the metal is the ejected photon. There is no additional kinetic energy resulting from the light so...
by Adelpha Chan 1B
Tue Oct 22, 2019 3:09 pm
Forum: Photoelectric Effect
Topic: Work Function
Replies: 9
Views: 57

Re: Work Function

Nikita Patra 3J wrote:What is the difference between the work function and the threshold frequency?


The two terms are used interchangeably by Professor Lavelle during the lecture. They both refer to the amount of energy required, or threshold, to remove electrons from the surface of a solid metal.
by Adelpha Chan 1B
Tue Oct 15, 2019 10:24 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7609
Views: 1019697

Re: Post All Chemistry Jokes Here

Q: Wanna hear a joke about sodium hypobromite?

A: NaBrO.
by Adelpha Chan 1B
Tue Oct 15, 2019 10:22 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7609
Views: 1019697

Re: Post All Chemistry Jokes Here

Chemistry jokes are sodium funny that I slapped my neon that one!
by Adelpha Chan 1B
Tue Oct 15, 2019 10:21 pm
Forum: Significant Figures
Topic: All students read this sig fig post [ENDORSED]
Replies: 116
Views: 10385

Re: All students read this sig fig post [ENDORSED]

Should I take sig figs while I am calculating one problem step by step? Should I use sig figs every step or should I just consider the sig figs on the very last calculation? Keep as many significant figures as you can during the middle steps to ensure you are getting an accurate answer. Rounding fo...
by Adelpha Chan 1B
Tue Oct 15, 2019 10:19 pm
Forum: Limiting Reactant Calculations
Topic: Showing Work for Limiting Reactant Calculations on Tests [ENDORSED]
Replies: 66
Views: 952

Re: Showing Work for Limiting Reactant Calculations on Tests [ENDORSED]

KatherineValdez_4B wrote:I have a question about significant figures. What number do we base the amount of significant figures we use? Like in any problem.


The amount of significant figures we use is based on the amount of significant figures in the values given in the question.
by Adelpha Chan 1B
Tue Oct 15, 2019 10:14 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Test 1 [ENDORSED]
Replies: 107
Views: 1886

Re: Test 1 [ENDORSED]

ahuang wrote:Does anyone know when we will be receiving our tests back?


Tests will be given back to you by the TA in discussion this week!
by Adelpha Chan 1B
Mon Oct 07, 2019 11:56 am
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7609
Views: 1019697

Re: Post All Chemistry Jokes Here

Q: How often do I tell chemistry jokes?
A: Periodically
by Adelpha Chan 1B
Mon Oct 07, 2019 11:53 am
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student [ENDORSED]
Replies: 147
Views: 84073

Re: Advice from a Medical Student [ENDORSED]

thank you for your advice, encouragement, and tips on how to succeed in this class!
by Adelpha Chan 1B
Mon Oct 07, 2019 11:48 am
Forum: Student Social/Study Group
Topic: Final Jitters
Replies: 63
Views: 18526

Re: Final Jitters

Something that helps me calm down is to make sure I am prepared well in advance. It helps to space out studying throughout the week, or even two weeks, before the test. This allows you to go at a slower and more comfortable pace without any, or at least reduced, time pressure.
by Adelpha Chan 1B
Mon Oct 07, 2019 11:45 am
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7609
Views: 1019697

Re: Post All Chemistry Jokes Here

Are you a non volitaile particle? Because you raise my boiling point.
by Adelpha Chan 1B
Mon Oct 07, 2019 11:44 am
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7609
Views: 1019697

Re: Post All Chemistry Jokes Here

Are you a carbon sample? Because I want to date you
by Adelpha Chan 1B
Mon Oct 07, 2019 11:40 am
Forum: Limiting Reactant Calculations
Topic: Showing Work for Limiting Reactant Calculations on Tests [ENDORSED]
Replies: 66
Views: 952

Re: Showing Work for Limiting Reactant Calculations on Tests [ENDORSED]

If the answer is correct, minimal work with dimensional analysis is fine. However, listing out each step makes it easier for you to check your answer and also increases the possibility of partial credit if you make a mistake on a step midway through.
by Adelpha Chan 1B
Tue Oct 01, 2019 11:51 pm
Forum: Empirical & Molecular Formulas
Topic: Formulas
Replies: 10
Views: 737

Re: Formulas

First, calculate the molar mass of the empirical formula. Then, divide the known molar mass of the compound by the molar mass of the empirical formula. The resulting value is the scale by which you multiply the integers of the empirical formula in order to obtain the molecular formula. Hope this exp...
by Adelpha Chan 1B
Tue Oct 01, 2019 11:48 pm
Forum: Empirical & Molecular Formulas
Topic: 5 Homework Problems Due
Replies: 21
Views: 191

Re: 5 Homework Problems Due

We just have to hand in any 5 homework questions from the section we are covering in class that week. However, it says on the syllabus that 1 in every 8 questions will be on the test (or midterm or final I'm not sure) so might as well do as many questions as possible.
by Adelpha Chan 1B
Tue Oct 01, 2019 11:45 pm
Forum: Empirical & Molecular Formulas
Topic: Mass % Composition
Replies: 7
Views: 62

Re: Mass % Composition

turning the given % to grams just makes it easier to visualize the distribution of weight among the compound. Once you convert the % to the corresponding grams (in relation to 100g), it is much easier to determine the empirical formula as you are now able to use these theoretical weights and compare...
by Adelpha Chan 1B
Tue Oct 01, 2019 11:41 pm
Forum: Empirical & Molecular Formulas
Topic: Empirical and Molecular Formulas [ENDORSED]
Replies: 5
Views: 52

Re: Empirical and Molecular Formulas [ENDORSED]

Yes they can! The empirical formula and molecular formula are the same if the ratios of the molecular formula cannot be reduced by any factor to smaller whole numbers.
by Adelpha Chan 1B
Sat Sep 28, 2019 7:57 pm
Forum: Empirical & Molecular Formulas
Topic: Empirical Formulas Rounding and Multiplying
Replies: 11
Views: 122

Re: Empirical Formulas Rounding and Multiplying

If the decimal is 2.26, I think you would have to multiply all the numbers you have already retrieved by 4. This would make 2.26 much closer to a whole number and avoid rounding numbers far from a whole number. This would be similar to the logic that follows how numbers ending in 0.5 and 0.33 are ul...

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