## Search found 36 matches

Sun Nov 22, 2020 10:30 pm
Forum: Electronegativity
Topic: Trick for remembering periodic trends
Replies: 11
Views: 64

### Re: Trick for remembering periodic trends

Learned this in highschool and found it to be really helpful for remembering certain trends: Periodic table: across down A ↓ ↑ I ↑ ↓ M ↓ ↑ E ↑ ↓ S -- ↑ A: atomic radius I: ionizing energy M: metallic properties E: electronegativity S: shells This is actually really helpful! Thanks for sharing this ...
Sun Nov 22, 2020 10:28 pm
Forum: Electronegativity
Replies: 8
Views: 31

### Re: Electronegativity versus atomic radius

I understand where we apply the principles of electronegativity but how does the trend of atomic radius relate to physical effects on the elements that we can use to study them? It is basically the opposite of each other, where the top right of the periodic table would have the highest electronegat...
Sun Nov 22, 2020 10:26 pm
Forum: Octet Exceptions
Topic: Octet Rule Exceptions
Replies: 20
Views: 142

### Re: Octet Rule Exceptions

Yolanda_Xing_3A wrote:I think I saw one YouTube video saying elements after #15, P, can form exceptions of octet rule. And so does the first few elements.

This is very helpful. thank you!
Sun Nov 22, 2020 10:25 pm
Forum: Lewis Structures
Topic: Expanded Valence
Replies: 11
Views: 40

### Re: Expanded Valence

Emma Ide 2E wrote:Hi, I'm confused about when an atom can have an expanded valence shell. I was adding up the number of valence electrons and then drawing a Lewis structure, but I had 2 electrons left over and was wondering if this was a case of expanded valence?

It revolves with period 3 and p block elements
Sun Nov 22, 2020 10:24 pm
Forum: SI Units, Unit Conversions
Topic: unit conversions
Replies: 13
Views: 112

### Re: unit conversions

When converting units do you just multiply by 10^x given number or is there a different way? For example if I convert centi to giga, I multiply the number I'm converting by 10^9 and leave it in scientific notation? I believe leaving it at 10^x would be the best as it would leave it in sig fig alrea...
Sun Nov 15, 2020 11:29 pm
Forum: Properties of Light
Topic: Is c always the speed of light?
Replies: 70
Views: 236

### Re: Is c always the speed of light?

Savannah Torella 1L wrote:When using the equation E= hc/ wavelength, is c always going to be the speed of light constant? Are there any instances were c is a different variable?

I think based on this class, it would always be used for speed.
Sun Nov 15, 2020 11:27 pm
Forum: Lewis Structures
Topic: Hydrogen Bonding
Replies: 12
Views: 25

### Re: Hydrogen Bonding

On a few of the Sapling questions, it mentioned that hydrogen bonding can not occur when the hydrogen atom is bonded to a carbon atom. It can only occur when hydrogen is bonded to either oxygen, fluorine, or nitrogen. I think he went over this in one of his lectures, but I'm still not entirely sure...
Sun Nov 15, 2020 11:26 pm
Forum: SI Units, Unit Conversions
Topic: Modules This Week
Replies: 8
Views: 51

### Re: Modules This Week

Emma_Barrall_1D wrote:Will there be modules this week posted to his website? They're really helpful!

I would hope he would post more as well! they were very helpful.
Sun Nov 15, 2020 11:25 pm
Forum: SI Units, Unit Conversions
Topic: picometer conversion
Replies: 13
Views: 65

### Re: picometer conversion

Does anyone know how to convert m to picometer? In a lot of the problems I see it seems like you just have to move the decimal place over and its usually a 3 digit number. Example 1.5x10^-10 m converts to 150 pm. Is there an actual mathematical way to compute it or is it just moving the decimal pla...
Sun Nov 15, 2020 11:23 pm
Forum: SI Units, Unit Conversions
Topic: Memorizing SI Units
Replies: 14
Views: 80

### Re: Memorizing SI Units

Are we expected to memorize SI units? I have some of them memorized, but could not remember what power of 10 a picometer was on the exam. I didn't see SI units given on the exam or on the formulas sheet, so I am guessing we should memorize them? Does anyone have any tricks they use to memorize them...
Sun Nov 08, 2020 11:35 pm
Forum: Electronegativity
Topic: Fluorine
Replies: 7
Views: 39

### Re: Fluorine

Binyu You wrote:Why does fluorine has the highest electronegativity in all elements of periodic table?

It has to do with its valence electron and that it is highly reactive
Sun Nov 08, 2020 11:28 pm
Forum: Ionic & Covalent Bonds
Topic: Electronegativity
Replies: 16
Views: 81

### Re: Electronegativity

Siwa Hwang 3G wrote:Why does Fluorine have the highest electronegativity energy?

Fluorine is really highly reactive as it only needs one more electrons.
Sun Nov 08, 2020 11:27 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Replies: 12
Views: 73

Savannah Torella 1L wrote:When do you want to use the Avogadro constant? How are you able to tell when it is needed?

It is important to use when converting moles to atoms or vice versa!
Sun Nov 08, 2020 11:26 pm
Forum: SI Units, Unit Conversions
Topic: conversion factors
Replies: 8
Views: 43

### Re: conversion factors

Hana Sigsbee 3A wrote:are there any specific conversion factors we are expected to know for the midterm that are not basic common knowledge ones?

I think the ones that are on the formula sheets are really important, and also the basic unit conversion like m to cm and etc
Sun Nov 08, 2020 11:24 pm
Forum: Balancing Chemical Reactions
Topic: Balancing Equations Coefficient Question
Replies: 15
Views: 71

### Re: Balancing Equations Coefficient Question

Sometimes when I am balancing chemical equations, I end up with coefficients that are not whole numbers. For example, there are 15 mols of O on one side, and on the other side I have to add a coefficient before O2. I can't put 7.5, even though 7.5 * 2 = 15, because I know coefficients have to be wh...
Sun Nov 01, 2020 11:01 pm
Forum: Significant Figures
Topic: When should I start looking at sig figs?
Replies: 18
Views: 100

### Re: When should I start looking at sig figs?

Whenever I'm solving a question, how do I know I can start looking at Sig figs. In other words, can I do it during my scratch work when I'm trying to figure out the final answer or do I use all numbers and decimals until I get to the final answer and then I use Sig Figs? I generally use sig fig for...
Sun Nov 01, 2020 11:00 pm
Forum: Significant Figures
Topic: 0's
Replies: 19
Views: 113

### Re: 0's

Matlynn Giles 1A wrote:Do the 0's following the decimal place count as SigFigs? For example the 2 0's after the decimal in 20.00.

Yes it does, in this case it would have 4 sig figs
Sun Nov 01, 2020 10:59 pm
Forum: Significant Figures
Topic: Sig Figs and Scientific Notation
Replies: 10
Views: 55

### Re: Sig Figs and Scientific Notation

Rayna Irving 3H wrote:When considering significant figures in a number, is the (10^x) part also included when using scientific notation or does that part not count?

No, generally only the first part would count!
Sun Nov 01, 2020 10:48 pm
Forum: SI Units, Unit Conversions
Topic: SI Units & US
Replies: 4
Views: 27

### Re: SI Units & US

noelle_lipschutz_3F wrote:This is a random question that popped into my head while doing SI units. Why hasn’t the US converted to SI units?

I believe that it is relatively difficult to convert now once the U.S has already adapted to the system we're using for awhile
Sun Nov 01, 2020 10:47 pm
Forum: SI Units, Unit Conversions
Topic: SI Unit for Mass
Replies: 8
Views: 58

### Re: SI Unit for Mass

Out of all the equations we've used so far in units 1 and 2, should mass always be in kg? I've been using g for mass for most of my work, but I noticed while reviewing the De Broglie equation that mass needs to be converted into kg for this example. Do some equations require mass in kg while some u...
Sun Oct 25, 2020 11:33 pm
Forum: Molarity, Solutions, Dilutions
Topic: Solute vs Solvent
Replies: 5
Views: 47

### Re: Solute vs Solvent

Hi! What makes something a solvent or a solute? How can we just know? I know that solutes are dissolved in solvents to create a solution such as salt and water, respectively. However, if given two items, how would I know? What makes something soluble I guess? Basically, the solvent is the substance...
Sun Oct 25, 2020 11:29 pm
Forum: Ionic & Covalent Bonds
Topic: Covalent Bonds
Replies: 9
Views: 47

### Re: Covalent Bonds

America Ramirez 3H wrote:How can you determine which one is stronger, out of ionic, covalent and hydrogen?

Hydrogen is the weakest out of the three, and I believe covalent and Ionic are both strong depending on its environment
Sun Oct 25, 2020 11:29 pm
Forum: Ionic & Covalent Bonds
Topic: Strength of bonds
Replies: 13
Views: 67

### Re: Strength of bonds

Queena Chu 1I wrote:What is the strength of types of bonds from highest to lowest?

I've learned that covalent bond is the strongest bond when compared to ionic but I also remember that in certain stances, an ionic bond may be very strong as well
Sun Oct 25, 2020 11:25 pm
Forum: Limiting Reactant Calculations
Topic: Midterm
Replies: 7
Views: 90

### Re: 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 ...
Sun Oct 25, 2020 11:24 pm
Forum: Balancing Chemical Reactions
Topic: States of matter in chem equations
Replies: 9
Views: 49

### Re: States of matter in chem equations

Hello, When we have to balance chem equations do we have to include the states of matter in all components. Additionally how do we know what state of matter a reactant/product is in? I believe it would be better to include the state of matter as it quite often appears together while balancing an eq...
Sun Oct 18, 2020 11:35 pm
Forum: Molarity, Solutions, Dilutions
Topic: Molarity test question
Replies: 8
Views: 84

### Re: Molarity test question

On the midterms or even the exams when expected to find molarity, will we be required to know how to substitute for any of the missing factors using the equation MfinalVfinal/Mnitial for example if we were finding the Vintial or will it always be the same factor we are finding? I am also wondering ...
Sun Oct 18, 2020 11:30 pm
Forum: Ionic & Covalent Bonds
Topic: Nonpolar and polar
Replies: 16
Views: 227

### Re: Nonpolar and polar

Jessica Tejero 3L wrote:Whats the easiest ways to tell whether a molecule is polar or non-polar?

I believe it is based on the electronegativity of the molecules
Sun Oct 18, 2020 11:26 pm
Forum: Ionic & Covalent Bonds
Topic: Is ionic or covalent stronger?
Replies: 31
Views: 331

### Re: Is ionic or covalent stronger?

I've found conflicting answers on the internet so I wanted to ask here. I was always taught throughout high school that covalent bonds are stronger than ionic bonds. But I came across a question in the textbook asking which of two substances would have a higher boiling point and I know that it has ...
Sun Oct 18, 2020 11:24 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Calculating number of moles of an element
Replies: 10
Views: 57

### Re: Calculating number of moles of an element

When calculating the number of moles of an element we always use 100g. I was wondering if we use 100g just for semplicity, and if there is any particular case where we should consider different quantities. I believe it is cause 100g is much easier for simplification, and also it was one of the thin...
Sun Oct 18, 2020 11:22 pm
Forum: Administrative Questions and Class Announcements
Topic: Built-in webcams/Equipment request [ENDORSED]
Replies: 22
Views: 699

### Re: Built-in webcams/Equipment request[ENDORSED]

Is there confirmation that webcams must be external? I'm getting a lot of mixed answers on whether built in cameras are allowed or not and if it's mandatory to have an external webcam and the equipment request instructs do not specify that. Are the webcams from the form only available to pick up in...
Sun Oct 11, 2020 9:12 pm
Forum: Significant Figures
Topic: When to use Sig Figs
Replies: 8
Views: 43

### Re: When to use Sig Figs

Normally I would just follow the trend of the problem, where if it uses scientific notation, then I would follow and use scientific notation and if it does not I would leave it as a regular number with right sig fig.
Sun Oct 11, 2020 9:07 pm
Forum: SI Units, Unit Conversions
Topic: Rounding
Replies: 20
Views: 126

### Re: Rounding

Are we suppose to always round to maintain the same sig figs?
Sun Oct 11, 2020 9:05 pm
Forum: Significant Figures
Topic: Sapling HW #4
Replies: 31
Views: 241

### Re: Sapling HW #4

Hi guys! I was doing question #4 on the homework and got a little confused on the sig figs. Would someone mind explaining why 950000 only has 2 sig figs compared 80060 having 4 sig figs. Initially I thought 950000 and 80060 would both only have 3 sig figs I believe this revolves with leading zeroes...
Sun Oct 11, 2020 9:04 pm
Forum: Balancing Chemical Reactions
Topic: Molar Mass
Replies: 23
Views: 137

### Re: Molar Mass

When a question requires us to calculate anything that needs molar masses, should we use the molar mass on the periodic tables that we have? e.g H- 1.00794 (6 sig figs) Is there a specific amount of sig figs we should use or it just depends on the periodic table given? I believe the specific amount...
Sun Oct 11, 2020 9:02 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Calculating Molar Mass (Sapling Week 1 #10)
Replies: 6
Views: 75

### Re: Calculating Molar Mass (Sapling Week 1 #10)

Were we supposed to look up the molar masses for this specific problem? I did not quite understand how to figure it.
Sun Oct 11, 2020 8:59 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Molar Mass and Molecular Mass Difference?
Replies: 19
Views: 163

### Re: Molar Mass and Molecular Mass Difference?

when do the units matter or when do you know which unit do you use?