Search found 59 matches

by ElizabethP1L
Sun Jun 10, 2018 11:33 pm
Forum: Lewis Acids & Bases
Topic: pH
Replies: 3
Views: 244

pH

Are we expected to know the pH of different solutions like tomato juice/lemon juice?
by ElizabethP1L
Sun Jun 10, 2018 11:21 pm
Forum: Lewis Acids & Bases
Topic: Strong Acid
Replies: 8
Views: 387

Strong Acid

what makes acids strong?
by ElizabethP1L
Sun Jun 10, 2018 11:18 pm
Forum: Significant Figures
Topic: Calculations
Replies: 3
Views: 195

Re: Calculations

It's advised that you avoid rounding/sig figs as you work out the problem. You should use them at the very end.
by ElizabethP1L
Sun Jun 10, 2018 11:14 pm
Forum: Polyprotic Acids & Bases
Topic: Coordination number [ENDORSED]
Replies: 3
Views: 649

Re: Coordination number [ENDORSED]

The coordination number refers to the number bonds around the central metal atom.
by ElizabethP1L
Thu Jun 07, 2018 10:16 pm
Forum: Naming
Topic: Naming Coordination Compounds [ENDORSED]
Replies: 1
Views: 181

Naming Coordination Compounds [ENDORSED]

Hi everyone! Did Dr. Lavelle say that we would need to know how to name coordination compounds, such as in 17.29? I thought I heard no, but I'm asking just to clarify. Thanks!
by ElizabethP1L
Thu Jun 07, 2018 10:02 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 4.19 d
Replies: 1
Views: 86

Re: 4.19 d

Hi! I'm not sure where you got the 95 degrees from because I don't see that in the solutions manual. However, I can tell you that it will definitely be sightly less than 120 degrees because of the lone pair. Tin (Sn) has four valence electrons . Two of them form bonds with the 2 Cl atoms to complete...
by ElizabethP1L
Thu Jun 07, 2018 9:57 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 4.21 a
Replies: 1
Views: 80

Re: 4.21 a

Hi! There are not five regions of electron density. The way the Lewis structure looks like is a double bond between 2 carbon atoms and two H atoms attached to each carbon. Since there are two central atoms here, we count the regions of electron density separately. You'll notice that around a single ...
by ElizabethP1L
Thu Jun 07, 2018 3:42 pm
Forum: Hybridization
Topic: Hybrid Orbitals
Replies: 3
Views: 188

Hybrid Orbitals

Hi everyone! I noticed some discrepancies on how we write the hybrid orbital for each molecule. I know that if there are five regions of electron density, for example, we use dsp3 for our hybrid orbitals (from the notes). However, my TA and the solutions manual both use sp3d instead. Are both accept...
by ElizabethP1L
Mon Jun 04, 2018 11:09 pm
Forum: Lewis Acids & Bases
Topic: Lewis and Bronsted Acid/Bases
Replies: 2
Views: 138

Lewis and Bronsted Acid/Bases

Hi everyone! I understand what defines an acid/base as Lewis or Bronsted. However, does this mean a Lewis base is always a Bronsted base and vice versa? Or can a base strictly be only Bronsted or Lewis? Similarly, is a Bronsted acid always a Lewis acid?
by ElizabethP1L
Sun Jun 03, 2018 9:51 pm
Forum: Ionic & Covalent Bonds
Topic: Polarizability
Replies: 7
Views: 287

Polarizability

Hey everyone! I am confused on the meaning of distorted as used in this sentence in the notes:

"Highly distorted electrons are described as being highly polarizable."

Thanks in advance! :)
by ElizabethP1L
Sun Jun 03, 2018 11:19 am
Forum: Electronegativity
Topic: Calculating electronegativity
Replies: 10
Views: 429

Re: Calculating electronegativity

I think we can just follow the general trends for that (increasing as we go to the right of the periodic table, decreasing as we go down). If values are given, remember that an electronegativity difference greater than 2 indicates an ionic bond and one less than 1.5 shows a covalent bond.
by ElizabethP1L
Sun Jun 03, 2018 11:15 am
Forum: Bond Lengths & Energies
Topic: Test 3 Q 8 [ENDORSED]
Replies: 9
Views: 446

Re: Test 3 Q 8 [ENDORSED]

You were supposed to look at the double bond in relation to the entire molecule. Since SO3 consists of only double bonds it will be stronger than SO4-2 with also has single bonds that are weaker. Hope this helped! :)
by ElizabethP1L
Fri Jun 01, 2018 10:59 am
Forum: Dipole Moments
Topic: London vs. Dipole
Replies: 3
Views: 375

London vs. Dipole

Hi everyone! I was just wondering what the main difference is between London forces and dipole-dipole. I thought they were essentially the same thing...Thanks in advance! :)
by ElizabethP1L
Sun May 27, 2018 10:51 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: PF3 molecular geometry
Replies: 2
Views: 388

Re: PF3 molecular geometry

Fluorine cannot form a double bond since it only needs one more electron to fulfill it's octet and it's unable to form expanded octets. Therefore, you would expect 3 single bonds and a lone pair on P. For VSEPR, it would not affect the general shape of the atom but angles would differ because lone p...
by ElizabethP1L
Sun May 27, 2018 10:47 pm
Forum: Resonance Structures
Topic: Radicals importance
Replies: 3
Views: 218

Re: Radicals importance

Radicals are generally unstable and don't really occur in nature.
by ElizabethP1L
Sun May 27, 2018 10:46 pm
Forum: Octet Exceptions
Topic: Expanded Octet
Replies: 2
Views: 277

Expanded Octet

Why is it that atoms in 3p shell and below may form expanded octets? Is it because of their access to the d-orbital?
by ElizabethP1L
Sun May 27, 2018 10:44 pm
Forum: Ionic & Covalent Bonds
Topic: Most covalent or ionic character
Replies: 3
Views: 368

Re: Most covalent or ionic character

More ionic character means that there is a greater difference in electronegativity between the 2 atoms allowing one to strip the other of an electron making it ionic. Typically, these atoms are farther away from each other on the periodic table than atoms of covalent character that would have simila...
by ElizabethP1L
Thu May 24, 2018 12:29 am
Forum: Lewis Structures
Topic: HW 3.45
Replies: 1
Views: 89

HW 3.45

Hi, everyone! I understand how to get the Lewis structure for ClNO2. Was I don't understand is why the solution manual only shows two resonance structures of it. One consists of the double bond of O to the left of N and the other shows the double bond of O above N. Why is there not a third resonance...
by ElizabethP1L
Wed May 23, 2018 1:45 pm
Forum: Lewis Structures
Topic: Ionic Compounds
Replies: 2
Views: 120

Re: Ionic Compounds

If you break up the individual molecules, you'll be able to recognize if it's ionic. In the case of ammonium chloride, NH4 has a positive charge (NH4+) while chlorine has a negative charge (Cl-). These opposite charges indicate that it's an ionic compound. Hope this helped!
by ElizabethP1L
Wed May 23, 2018 1:38 pm
Forum: Lewis Structures
Topic: H Formal Charge
Replies: 4
Views: 152

Re: H Formal Charge

I understand the formal charge would be zero. However, why don't we label it as such? When other atoms in the Lewis structure have a formal charge of zero we indicate it. Would it be wrong to include it?
by ElizabethP1L
Wed May 23, 2018 1:05 am
Forum: Lewis Structures
Topic: H Formal Charge
Replies: 4
Views: 152

H Formal Charge

Hey, everyone! Is there a reason why the formal charge for Hydrogen is never calculated? I've noticed the solutions manual never mentions a formal charge for H. Thanks in advance!
by ElizabethP1L
Tue May 22, 2018 8:58 pm
Forum: Lewis Structures
Topic: Carbon Monoxide Lewis Structure
Replies: 3
Views: 227

Re: Carbon Monoxide Lewis Structure

So, in other words, CO is an example of a coordinate covalent bond?
by ElizabethP1L
Tue May 22, 2018 3:35 pm
Forum: Coordinate Covalent Bonds
Topic: Coordinate Covalent Bond Definition
Replies: 14
Views: 668

Coordinate Covalent Bond Definition

Hey, everyone! I thought the definition of a coordinate covalent bond wasn't that clear from the notes, so I looked it up on Google. It says that a coordinate covalent bond is when both electrons in a bond come from the same atom. I just wanted to confirm that this is the correct definition. Thanks ...
by ElizabethP1L
Tue May 22, 2018 12:35 am
Forum: Lewis Structures
Topic: 3.41 part c
Replies: 4
Views: 144

Re: 3.41 part c

My TA says that when there are multiple carbons we should try to line them up horizontally and bond them. Then, try to fit in all the other components and complete their octets around the molecule. You should worry about hydrogen last since they are the easiest to accommodate since they only need on...
by ElizabethP1L
Tue May 22, 2018 12:26 am
Forum: Lewis Structures
Topic: Question about Resonance Structures
Replies: 1
Views: 69

Re: Question about Resonance Structures

Resonance structures help us to determine which form of the molecule is most stable (and therefore what would most likely be found in nature). Additionally, it shows us that molecules have different ways of distributing their electrons and bonds (they are not static the way a single Lewis structure ...
by ElizabethP1L
Tue May 22, 2018 12:21 am
Forum: Lewis Structures
Topic: Carbon Monoxide Lewis Structure
Replies: 3
Views: 227

Carbon Monoxide Lewis Structure

Hey, everyone! I'm just a bit confused on the Lewis structure for carbon monoxide with consists for a triple bond with oxygen and two lone pairs (one pair on C and the other on O). For reference, see part C of HW problem 3.49. How can carbon even form a triple bond and have a lone pair left over if ...
by ElizabethP1L
Sat May 19, 2018 10:21 pm
Forum: Ionic & Covalent Bonds
Topic: Ionic bonds
Replies: 6
Views: 228

Re: Ionic bonds

When do we place brackets around ions? I believe that's when you draw a Lewis structure for a charged molecule with covalent bonds like NH4+. In this case, nitrogen would have 4 valence electrons like carbon instead of the expected 5. To account for this lost electron you can put brackets around th...
by ElizabethP1L
Sat May 19, 2018 8:34 pm
Forum: Resonance Structures
Topic: Resonance Structures
Replies: 9
Views: 439

Resonance Structures

Should all resonance structures have the same formal charge?
by ElizabethP1L
Sat May 19, 2018 8:31 pm
Forum: Lewis Structures
Topic: Test #3
Replies: 11
Views: 381

Re: Test #3

Will we have to use significant figures for this test just like midterm?
by ElizabethP1L
Sun May 13, 2018 4:28 pm
Forum: Lewis Structures
Topic: monatomic ion
Replies: 2
Views: 86

Re: monatomic ion

A monatomic ion refers to an ion composed of a single atom like H. The charge on this monatomic ion would be +1. The opposite of a monatomic ion would be a polyatomic ion like NH4+ or PO4-3. Hope this helped! :)
by ElizabethP1L
Sun May 13, 2018 4:26 pm
Forum: Lewis Structures
Topic: Lewis Structure [ENDORSED]
Replies: 3
Views: 124

Re: Lewis Structure [ENDORSED]

Hi! That's a very broad question! From drawing them out for homework and in class, I've noticed oxygen tends to form double bond since it has 6 valence electrons and needs two more. I don't think there's any way to know for sure. I would just try different combinations to fill each atom's octet and ...
by ElizabethP1L
Sun May 13, 2018 4:23 pm
Forum: Lewis Structures
Topic: Expanded Octet
Replies: 2
Views: 106

Expanded Octet

Hey, everyone! So I know elements from 3p and below on the periodic table are able to form an expanded octet (that is, they can have more than 8 overall electrons). However, do they ALWAYS form expanded octets (e.g. will Cl aways have more than 8 electrons in a Lewis structure)? Thanks in advance :)
by ElizabethP1L
Sun May 06, 2018 11:33 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: post Module Heisenberg
Replies: 1
Views: 117

post Module Heisenberg

Hey, everyone! I'm not really sure how to do the following problem. I keep getting he wrong answer regardless of how many times I attempt to calculate it: The hydrogen atom has a radius of approximately 0.05 nm. Assume that we know the position of an electron to an accuracy of 1 % of the hydrogen ra...
by ElizabethP1L
Sun May 06, 2018 10:09 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: 4s and 3d
Replies: 4
Views: 152

Re: 4s and 3d

Andre-1H wrote:So, even though we are not responsible for the elements that occupy these orbitals, could we then apply this to the next row and say that 4d is lower in energy than 5s? Or would that be the only exception for this line of thinking?


Yes, that's right.
by ElizabethP1L
Sun May 06, 2018 4:07 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: 4s and 3d
Replies: 4
Views: 152

4s and 3d

I know that the 4s orbital is actually higher than the 3d orbital and the exceptions in electron configurations that follow this rule. However, why is it that the 4s orbital is higher in energy? It's something I have just memorized, but I'd like to know the reason why. Thanks in advance! :)
by ElizabethP1L
Sat May 05, 2018 9:50 pm
Forum: Ionic & Covalent Bonds
Topic: Midterm Topics [ENDORSED]
Replies: 33
Views: 1915

Re: Midterm Topics [ENDORSED]

Are we expected to know significant figures for the midterm exam? Thanks in advance! :)
by ElizabethP1L
Sun Apr 29, 2018 7:52 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Balmer Series
Replies: 2
Views: 98

Balmer Series

What kind of light is used in the Balmer series?
by ElizabethP1L
Sun Apr 29, 2018 7:50 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Lyman Series
Replies: 4
Views: 152

Lyman Series

Wat kind of light is used in the Lyman series?
by ElizabethP1L
Sun Apr 29, 2018 5:16 pm
Forum: Properties of Light
Topic: Homework question 1.27 [ENDORSED]
Replies: 3
Views: 129

Re: Homework question 1.27 [ENDORSED]

Just divide the number you found that's emitted in two seconds by Avogadro's number (6.02*10^23) since there are that many atoms in just a single mole. Hope this helped! :)
by ElizabethP1L
Sun Apr 29, 2018 5:12 pm
Forum: Ideal Gases
Topic: Reading the textbook [ENDORSED]
Replies: 129
Views: 75225

Re: Reading the textbook [ENDORSED]

I think Dr. Lavelle is very thorough when it comes to explaining things, so maybe just use the textbook to brush up on something or for diagrams/visuals. Sometimes the practice problems throughout the chapter are good for solving the math in the exercises. Hope this helped! :)
by ElizabethP1L
Sun Apr 29, 2018 5:08 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7609
Views: 1019927

Re: Post All Chemistry Jokes Here

What kind of fish is made up of two sodium atoms?

Answer: 2 NA
by ElizabethP1L
Tue Apr 24, 2018 8:42 pm
Forum: Properties of Electrons
Topic: Information Provided on Exam
Replies: 6
Views: 298

Information Provided on Exam

Does anyone know if we will be provided the wavelengths of the electromagnetic spectrum ?
by ElizabethP1L
Tue Apr 24, 2018 6:45 pm
Forum: Photoelectric Effect
Topic: Difference between photon and particle?
Replies: 2
Views: 114

Difference between photon and particle?

Hey, everyone! As I was studying the photoelectric effect I was a bit confused on something. Can anyone explain the difference between a photon and a particle if there is one? Thanks in advance!
by ElizabethP1L
Sun Apr 22, 2018 7:48 pm
Forum: General Science Questions
Topic: Tools for remembering equations
Replies: 5
Views: 514

Re: Tools for remembering equations

Don't know of many myself :( But, remember, you aren't expected to know the equations! They will be provided to you on any exam, according to Dr. Lavelle! Hope this helped! :)
by ElizabethP1L
Sun Apr 22, 2018 7:45 pm
Forum: Properties of Light
Topic: frequency and wavelength [ENDORSED]
Replies: 5
Views: 210

Re: frequency and wavelength [ENDORSED]

The equation most frequently used with it is the product of frequency and wavelength equaling the speed of light (3*10^8). Wavelength and frequency have an inverse relationship meaning that an increase in wavelength leads to a decrease in frequency and an increase in frequency leads to a decrease in...
by ElizabethP1L
Sun Apr 22, 2018 7:43 pm
Forum: Molarity, Solutions, Dilutions
Topic: Units - L or mL? [ENDORSED]
Replies: 15
Views: 604

Re: Units - L or mL? [ENDORSED]

L is definitely more preferred. all the solutions in the solutions manual convert from mL to L unless the problem states that the answer should be in mL.
by ElizabethP1L
Thu Apr 19, 2018 9:02 pm
Forum: Empirical & Molecular Formulas
Topic: empirical vs molecular
Replies: 5
Views: 284

Re: empirical vs molecular

The empirical formula just gives us the relative number of atoms not the actual number. Therefore, usually the empirical formula will be much smaller than the molecular formula. If you notice however, multiplying each element of the empirical formula by the same number results in the molecular formu...
by ElizabethP1L
Sun Apr 15, 2018 11:27 pm
Forum: Properties of Light
Topic: Properties of Light
Replies: 4
Views: 126

Re: Properties of Light

No, Dr.Lavelle said we would be provided with all constants and any outside information, including a periodic table. Hope this helped :)
by ElizabethP1L
Sun Apr 15, 2018 11:23 pm
Forum: SI Units, Unit Conversions
Topic: Avogadro #
Replies: 9
Views: 432

Re: Avogadro #

Avogadro's number is always 6.022*10^23. We mostly use it in stoichiometry. The most common uses for it is converting from moles to atoms. To do this, simply multiply the molar mass by Avogadro's number! To go from atoms to moles, divide the number of atoms you have by Avogadro's number. Hope this h...
by ElizabethP1L
Sun Apr 15, 2018 11:19 pm
Forum: Balancing Chemical Reactions
Topic: Balancing Equation
Replies: 7
Views: 523

Re: Balancing Equation

Well, in general, it's important to remember the basic rules and start balancing the least abundant element in a chemical equation to avoid this problem. If you still encounter it, however, you should just use a fraction to balance it temporarily. For example, let's say you need 19 Fe, but that mean...
by ElizabethP1L
Tue Apr 10, 2018 5:17 pm
Forum: Balancing Chemical Reactions
Topic: Balancing Chemical Equations Online Module Assessment
Replies: 1
Views: 154

Balancing Chemical Equations Online Module Assessment

Hey, everyone! I had a conceptual question about the problem below: 19. During a summer camping weekend 4 moles of butane (C4H10) gas were used for cooking. Chose the right balanced equation for the combustion of 4 moles of butane gas. What is the net number of moles of gas produced? A. 4C4H10(g) + ...
by ElizabethP1L
Mon Apr 09, 2018 5:30 pm
Forum: Limiting Reactant Calculations
Topic: Avogadro's Number
Replies: 1
Views: 88

Re: Avogadro's Number

That's a very broad question! Avogadro's number is popularly used in mole conversions and stoichiometry. Typically if we want to know the number of atoms or molecules in a mole, we multiply the molar mass by Avogadro's number. To convert from atoms to moles, we must divide the atom amount by Avogadr...
by ElizabethP1L
Mon Apr 09, 2018 5:02 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Molar Mass [ENDORSED]
Replies: 2
Views: 189

Re: Molar Mass [ENDORSED]

Atomic mass is simply the mass of a single atom of an element (like an atom of Na). This can be found under the element symbol on a periodic table. In this case the atomic mass is 11. The atomic mass is composed of the mass of protons and neutrons. The molar mass refers to mass of ions, atoms, or mo...
by ElizabethP1L
Sat Apr 07, 2018 12:46 pm
Forum: Molarity, Solutions, Dilutions
Topic: HW G.25
Replies: 1
Views: 92

HW G.25

Hey, everyone! I just had a general question about HW G.25. I understand the math behind it. However, the question asks if a very dilute solution of a substance X (presumably the solute) can still have an effect. I immediately thought yes because Dr. Lavelle mentioned that changing the volume of a s...
by ElizabethP1L
Sat Apr 07, 2018 12:31 pm
Forum: Balancing Chemical Reactions
Topic: H.3
Replies: 3
Views: 156

Re: H.3

Hi, Noah! I actually don't know much about the Hill System, unfortunately. In my own case, I intuitively knew the H4 would follow the Si. However, usually when the H comes first, it usually means its an acid: H2CO3 (carbonic acid) HNO3 (nitric acid) HClO4 (perchloric acid) etc.... Therefore, if it w...
by ElizabethP1L
Fri Apr 06, 2018 4:07 pm
Forum: Empirical & Molecular Formulas
Topic: Molecular Formula f.19
Replies: 2
Views: 534

Re: Molecular Formula f.19

The first step is to determine the number of MOLES of each element to find the molar ratio, which will help us derive the empirical formula. The molecular formula can then be found using this formula. Since the problem did NOT specify how many grams of each atom we have, we can go ahead and assume t...
by ElizabethP1L
Fri Apr 06, 2018 3:41 pm
Forum: Balancing Chemical Reactions
Topic: How to know the state of the molecules [ENDORSED]
Replies: 6
Views: 259

Re: How to know the state of the molecules [ENDORSED]

Ideally, the problem will give you the states already. However, you don't NEED them to balance the equation. Take a look at HW problem H.1 under fundamentals for example! What's important in balancing chemical equations is the conservation of mass. As long as the same number of moles of H are presen...
by ElizabethP1L
Fri Apr 06, 2018 3:30 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Which mass of oxygen should be used? [ENDORSED]
Replies: 23
Views: 962

Re: Which mass of oxygen should be used? [ENDORSED]

That doesn't make a big difference. Since these calculations are not being used for lab procedures, it is not important to be 100% precise. When you find the empirical formula, you round ratios as well. For example 5.12 moles of C can just be denoted 5 C in the empirical formula. Therefore, it is ok...
by ElizabethP1L
Fri Apr 06, 2018 3:24 pm
Forum: SI Units, Unit Conversions
Topic: What is the notation for molar mass?
Replies: 15
Views: 623

Re: What is the notation for molar mass?

Molar Mass is expressed as a capital letter M and should not be confused with molarity. Dr. Lavelle underlines the M for molarity to distinguish the two. The units for molar mass are g/mol. Hope this helped! :)

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