Search found 34 matches

by Sisi Li 1F
Wed Jul 31, 2019 12:20 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Formula from Name
Replies: 4
Views: 193

Re: Formula from Name

There's a page in the textbook that gives you a pretty comprehensive step by step of the process! In the 6th edition it's on page 741. I would also recommend watching some youtube videos on it, if you need some walk through of examples.
by Sisi Li 1F
Sun Jul 28, 2019 10:38 pm
Forum: Properties & Structures of Inorganic & Organic Bases
Topic: Alkali Metals and Alkaline Earth Metals
Replies: 1
Views: 136

Re: Alkali Metals and Alkaline Earth Metals

They are incredibly reactive- Alkali metals form 1+ ions and Alkaline Earth Metals form 2+ ions. As a result, they react strongly with water to form hydroxides
by Sisi Li 1F
Sun Jul 28, 2019 10:32 pm
Forum: Sigma & Pi Bonds
Topic: Importance of Sigma/Pi Bonds
Replies: 5
Views: 170

Re: Importance of Sigma/Pi Bonds

It's very VERY important to categorize sigma/pi bonds-- it helps us determine hybridization in our homework problems. It can also help determine the shapes of molecules. It's a crucial topic that we learn in the syllabus that will also be covered on the final
by Sisi Li 1F
Sun Jul 28, 2019 10:25 pm
Forum: Bronsted Acids & Bases
Topic: Bronsted and Lewis Acids and Bases
Replies: 2
Views: 168

Re: Bronsted and Lewis Acids and Bases

The Bronsted Acids and Bases can be restrictive as it focuses primarily on acids and bases acting as proton donors and acceptors, and in certain conditions this theory doesn't fit. The Lewis Acids and Bases alternatively looks at electrons which are donated/accepted. This helps predict a wider varie...
by Sisi Li 1F
Sun Jul 28, 2019 10:15 pm
Forum: Electronegativity
Topic: How to determine which bond is more covalent?
Replies: 2
Views: 150

How to determine which bond is more covalent?

This was on test 2-- telling which bonds are more ionic and which are more covalent. For the bonds F-CL and P-O, they were so similar so it was tough to tell which one was more ionic. How can I reason through this, and other similar problems such as determining elements that are diagonal to each oth...
by Sisi Li 1F
Sun Jul 28, 2019 10:08 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Geometry vs molecular shape
Replies: 6
Views: 211

Re: Geometry vs molecular shape

Molecular shape only considers the bonding pairs of a molecule. When there are lone pairs, you look at the geometry, or electron arrangement.
by Sisi Li 1F
Sun Jul 28, 2019 10:06 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular shape
Replies: 3
Views: 189

Re: Molecular shape

The shaded in triangle simply means that the electron is pointing towards you, while the dashed triangle means it's angled away. For the final, I wouldn't worry about having to know about this.
by Sisi Li 1F
Thu Jul 25, 2019 3:24 pm
Forum: Naming
Topic: Fe------ferrate? [ENDORSED]
Replies: 8
Views: 384

Re: Fe------ferrate? [ENDORSED]

For iron, when it has a negative charge, the name becomes ferrate- this is the latin term.
by Sisi Li 1F
Sun Jul 21, 2019 8:56 pm
Forum: Bond Lengths & Energies
Topic: Bond lengths [ENDORSED]
Replies: 2
Views: 289

Re: Bond lengths [ENDORSED]

Not the specific bond length, but know which bonds will result in shorter bonds and which results in longer bonds, and how that affects bond strength.
by Sisi Li 1F
Sun Jul 21, 2019 8:23 pm
Forum: Ionic & Covalent Bonds
Topic: Dipoles
Replies: 7
Views: 387

Re: Dipoles

Dipoles are polar unless they cancel out in elements such as CCl4. Hydrogen bonding is a type of dipole-dipole interaction that occurs when F, O, C, and N are bonded to a hydrogen.
by Sisi Li 1F
Sun Jul 21, 2019 8:19 pm
Forum: Ionic & Covalent Bonds
Topic: Inter and Intra
Replies: 8
Views: 365

Re: Inter and Intra

Intramolecular- within the compound, like ionic and covalent bonding
Intermolecular- with other compounds, such as dipole-dipole, hydrogen, london forces, etc.
by Sisi Li 1F
Sun Jul 21, 2019 8:16 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angles
Replies: 3
Views: 96

Re: Bond Angles

Yes, you'd have to predict angles such as 109.5, 90, and 180. For elements in which areas of electron density are lone pairs instead of bonding pairs, the angles will change, but you won't need to know the exact angle, just know whether it's greater or less than the known angles. For example, a tetr...
by Sisi Li 1F
Sun Jul 21, 2019 8:12 pm
Forum: Octet Exceptions
Topic: Lewis Acids and Bases
Replies: 10
Views: 413

Re: Lewis Acids and Bases

Lewis acids are electron acceptors, they usually have an unfilled valence and will accept electron pairs from Lewis bases, which are electron donors that give away electron pairs.
by Sisi Li 1F
Sun Jul 21, 2019 8:08 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Polar v. Nonpolar
Replies: 11
Views: 269

Re: Polar v. Nonpolar

Dipole moments occur wherever there is an unequal sharing of electrons, which makes the compound polar. If you look at the elements and see that they have different electronegativities, then electrons will be unequally shared. The element with the greater electronegativity will pull electrons toward...
by Sisi Li 1F
Thu Jul 18, 2019 6:50 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Is test 2 going to cover electron configuration for ions?
Replies: 1
Views: 216

Is test 2 going to cover electron configuration for ions?

Our homework for ch 3 covers electron configuration of ions, but the outline doesn't include that in the list of things to know. I'm wondering if we would still be tested on that since it was already covered in the midterm.

I posted this on the wrong forum so I'm reposting on the right one :'(
by Sisi Li 1F
Sun Jul 14, 2019 10:45 pm
Forum: Ionic & Covalent Bonds
Topic: What to do if electronegativity difference is between 1.5 and 2? [ENDORSED]
Replies: 3
Views: 246

What to do if electronegativity difference is between 1.5 and 2? [ENDORSED]

In lecture, Dr Lavelle talked about how to determine ionic and covalent bonds with electronegativity differences. He said that if the difference is between 2 and 1.5, then we need to look at the periodic table and see if the compound is a salt. Can someone further explain this?
by Sisi Li 1F
Sun Jul 14, 2019 10:41 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polarizing Power [ENDORSED]
Replies: 8
Views: 420

Re: Polarizing Power [ENDORSED]

Polarizing power is how much a cation distorts a polarizable anion. The charge of the cation causes the electron cloud of the anion to distort as it's attracted to the cation. At first, Lavelle made a distinction between covalent and ionic bonds because covalent bonds creates compounds whereas ionic...
by Sisi Li 1F
Sun Jul 14, 2019 10:35 pm
Forum: Lewis Structures
Topic: Drawing lewis structures
Replies: 5
Views: 265

Re: Drawing lewis structures

I don't think the order of each element matters, just make sure that the formal charge matches with the charge given and you should be fine
by Sisi Li 1F
Sun Jul 14, 2019 10:32 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge
Replies: 12
Views: 526

Re: Formal Charge

I'd say you should show your formal charge calculations, just to show that you know a certain lewis structure is correct. Could depend on the TA though.
by Sisi Li 1F
Sun Jul 14, 2019 10:30 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Which do you prioritize first
Replies: 10
Views: 373

Re: Which do you prioritize first

Prioritize valence electrons first, then look at the formal charge
by Sisi Li 1F
Sun Jul 14, 2019 10:27 pm
Forum: Ionic & Covalent Bonds
Topic: Difference Between Ionic and Covalent
Replies: 8
Views: 261

Re: Difference Between Ionic and Covalent

Covalent bond creates compounds because the electrons are being shared to fill the octet, whereas in ionic bonds, ions are created as electrons donate/accept electrons to fill their octet
by Sisi Li 1F
Sun Jul 07, 2019 6:36 pm
Forum: Photoelectric Effect
Topic: Photo electric effect
Replies: 7
Views: 321

Re: Photo electric effect

The vacuum essentially prevents other elements that are in the air from interacting with the experiment, which would throw off the results
by Sisi Li 1F
Sun Jul 07, 2019 6:34 pm
Forum: Properties of Light
Topic: Speed of Light
Replies: 41
Views: 786

Re: Speed of Light

In the context of this class, it should always be treated as a constant.
by Sisi Li 1F
Sun Jul 07, 2019 2:21 am
Forum: Properties of Light
Topic: Class lecture
Replies: 2
Views: 211

Re: Class lecture

We use hydrogen because it has 1 electron, so it's must easier to study the quantum world because when there are multiple electrons it complicates things
by Sisi Li 1F
Sat Jul 06, 2019 8:31 pm
Forum: Einstein Equation
Topic: Energy of photon [ENDORSED]
Replies: 12
Views: 615

Re: Energy of photon [ENDORSED]

You can use E=hv, or combine this with lamba=c/v to get E=hc/lambda
by Sisi Li 1F
Sat Jul 06, 2019 8:28 pm
Forum: Photoelectric Effect
Topic: Photo electric diagram
Replies: 1
Views: 206

Re: Photo electric diagram

I believe metals are the only elements that donate electrons when excited, whereas nonmetals hold on to their electrons more. Although I don't think that is too important to know for the midterm
by Sisi Li 1F
Sat Jul 06, 2019 8:25 pm
Forum: Einstein Equation
Topic: E=hv
Replies: 41
Views: 1502

Re: E=hv

E is the energy of the photon. The work function, on the other hand, would give you the energy needed to remove an electron.
by Sisi Li 1F
Sat Jun 29, 2019 7:34 pm
Forum: Significant Figures
Topic: Determining sig figs
Replies: 10
Views: 578

Re: Determining sig figs

Decimal points will tell you how precise a number we are measuring. Looking at the number 100, you don't really know for sure whether 100 is an estimate or not- perhaps it was obtained by rounding up or down from a different number, but you don't really know for sure. On the other hand, 100. tells y...
by Sisi Li 1F
Wed Jun 26, 2019 11:55 pm
Forum: Empirical & Molecular Formulas
Topic: Homework E.15 Solutions
Replies: 4
Views: 243

Homework E.15 Solutions

On the solution manual (6th edition), there's a Calcium in the equation. Why is that? It is also unclear to me why they subtracted 34.02 g/mol from the total molar mass of the metal.
by Sisi Li 1F
Wed Jun 26, 2019 11:49 pm
Forum: SI Units, Unit Conversions
Topic: Use of Kelvin
Replies: 6
Views: 291

Re: Use of Kelvin

Basically temperature can't drop further than 0 Kelvin, it's the lowest limit.
by Sisi Li 1F
Wed Jun 26, 2019 10:00 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Theoretical/Actual Yield
Replies: 6
Views: 260

Re: Theoretical/Actual Yield

It seems that because most of our problems are given in terms of grams, yields will also be in grams
by Sisi Li 1F
Wed Jun 26, 2019 9:57 pm
Forum: SI Units, Unit Conversions
Topic: Can someone explain why we use kg for mass as the base unit?
Replies: 9
Views: 299

Re: Can someone explain why we use kg for mass as the base unit?

I understand why using grams is ideal, but it's just the fact that kg is the base unit part that isn't clear to me.
by Sisi Li 1F
Wed Jun 26, 2019 9:47 pm
Forum: SI Units, Unit Conversions
Topic: Can someone explain why we use kg for mass as the base unit?
Replies: 9
Views: 299

Can someone explain why we use kg for mass as the base unit?

In lecture, Dr. Lavelle said that kilograms was used for the base unit for mass. However, when we do conversions, we always write the powers of 10 with respect to grams. Can anyone explain why that is? Or am I misunderstanding something?
by Sisi Li 1F
Wed Jun 26, 2019 3:47 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Balancing Equations [ENDORSED]
Replies: 25
Views: 377

Re: Balancing Equations [ENDORSED]

In lecture, Dr. Lavelle said that all stoichiometric coefficients must be the lowest whole number, so I imagine you would be docked points for leaving any coefficients in fractions.

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