Search found 51 matches

by Camellia Liu 1J
Tue Dec 03, 2019 6:07 pm
Forum: Conjugate Acids & Bases
Topic: Conjugate Base
Replies: 4
Views: 36

Re: Conjugate Base

I think that you would remove the H at the end. The conjugate base of acetic acid is CH3COO-.
by Camellia Liu 1J
Tue Dec 03, 2019 6:04 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Plane
Replies: 2
Views: 22

Re: Plane

To add on, if the atom has a pi bond, we know that it will be on the same plane because you can't rotate pi bonds or they will break.
by Camellia Liu 1J
Tue Dec 03, 2019 6:02 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: Concentration
Replies: 2
Views: 21

Re: Concentration

We use H3O+ and H+ interchangeably, since H3O+ is basically the hydrated form of H+. H+ can't by itself exist in an aqueous solution because there's an attraction between its positive charge and the slightly negative charge on oxygen in the water molecule. H3O+ is just a better and more accurate rep...
by Camellia Liu 1J
Tue Dec 03, 2019 5:55 pm
Forum: Identifying Acidic & Basic Salts
Topic: Cl- and NaCl
Replies: 2
Views: 22

Re: Cl- and NaCl

NaCl is neutral in nature, therefore, it doesn't affect the pH.
by Camellia Liu 1J
Tue Dec 03, 2019 5:46 pm
Forum: Lewis Acids & Bases
Topic: Cations and Anions
Replies: 3
Views: 30

Re: Cations and Anions

Lewis acids are electron acceptors and lewis bases are electron donors. Whether the cation is a Lewis acid would depend on how many empty orbitals it has. A Lewis base has to have at least one lone pair of electrons. I think that all anions can be Lewis bases but not all Lewis bases are anions.
by Camellia Liu 1J
Wed Nov 27, 2019 11:43 am
Forum: Sigma & Pi Bonds
Topic: Question on Test 2
Replies: 11
Views: 162

Re: Question on Test 2

There is actually also one hydrogen bond between H-N. Maybe we were graded differently or something but my answer was 9 hydrogen bonding sites, with 8 lone-pair sites and one hydrogen bond.
by Camellia Liu 1J
Wed Nov 27, 2019 11:37 am
Forum: Lewis Acids & Bases
Topic: Acid and Base Strength
Replies: 7
Views: 49

Re: Acid and Base Strength

I believe a hint given in lecture too is that if you are given a Ka or a Kb in a question, you will automatically know that it is a weak acid or base since it shows that the substance does not dissociate completely.
by Camellia Liu 1J
Wed Nov 27, 2019 11:27 am
Forum: Ionic & Covalent Bonds
Topic: Dative Covalent Bonding
Replies: 4
Views: 58

Re: Dative Covalent Bonding

Dative bonding is just another name for coordinate covalent bonding. It's a covalent bond where both electrons are supplied by the same atom, as compared to a simple covalent bond where each atom supplies one electron to the bond for "sharing." In the case of ligands, they are attached to ...
by Camellia Liu 1J
Wed Nov 27, 2019 11:23 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Ligands
Replies: 6
Views: 49

Re: Ligands

Since ligands are ions/neutral molecules that bond to the central metal atom, they have at least one donor atom (that has a lone pair) that can be used to form covalent bonds with the central atom. Since they "donate" their electrons to the central atom, they act as Lewis bases.
by Camellia Liu 1J
Wed Nov 27, 2019 11:11 am
Forum: Dipole Moments
Topic: H-bonds and H-bonding
Replies: 2
Views: 59

Re: H-bonds and H-bonding

Another way to think about it is that we usually use the term 'hydrogen bond' when talking about intermolecular forces. Its the strongest intermolecular force, but it only amounts to approximately 1/10 the strength of a covalent bond. When we talk about hydrogen bonded to another atom, we would usua...
by Camellia Liu 1J
Tue Nov 19, 2019 4:33 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: SO3(2-)
Replies: 3
Views: 26

Re: SO3(2-)

I believe that it is polar, as through the Lewis structure and VSEPR, you find that the molecule as the shape trigonal pyramidal. Therefore, it would experience dipole moments, making it slightly polar.
by Camellia Liu 1J
Tue Nov 19, 2019 7:28 am
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: Strength of Intermolecular Forces
Replies: 3
Views: 22

Re: Strength of Intermolecular Forces

Hydrogen bonding occurs when a hydrogen atom is bonded to a small, strongly electronegative atom (specifically, N, O, or F) and is attracted to a lone pair of electrons on another N, O, or F atom. It might be better to look at the strength of other intermolecular forces within these atoms, since HCL...
by Camellia Liu 1J
Tue Nov 19, 2019 7:19 am
Forum: Sigma & Pi Bonds
Topic: Symmetry of Electron Density
Replies: 1
Views: 26

Re: Symmetry of Electron Density

Sigma bonds form from the pairing of electron spins between two atoms when they interact end-to-end, resulting in an electron density with cylindrical symmetry around the internuclear axis. The electron density is concentrated in between the nuclei of the bonded atoms. Pi bonds form when two orbital...
by Camellia Liu 1J
Tue Nov 19, 2019 7:11 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Structure of HCN
Replies: 2
Views: 22

Re: Structure of HCN

We know that H is never the central atom since it can't form more than one bond, so that rules it out. HNC and HCN are actually both real structures so technically you could have it as the central atom (if you are taking about hydrogen isocyanide vs. hydrogen cyanide). But if we take HCN as a struct...
by Camellia Liu 1J
Thu Nov 14, 2019 10:26 am
Forum: Bond Lengths & Energies
Topic: Strongest Bonds
Replies: 11
Views: 125

Re: Strongest Bonds

Covalent bonds are the strongest, followed by ionic bonds. Hydrogen bonds are the strongest type of intermolecular force, followed by London forces and dipole interactions.
by Camellia Liu 1J
Thu Nov 14, 2019 10:15 am
Forum: Determining Molecular Shape (VSEPR)
Topic: 2E.11d)
Replies: 2
Views: 28

Re: 2E.11d)

Lewis structures don't determine the shapes of the molecules, but it is the first step in helping to predict it as it helps to identify the bond pairs and the lone pairs. Then, you can apply VSEPR to determine molecular shape/geometry.
by Camellia Liu 1J
Wed Nov 13, 2019 7:56 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 2E.15
Replies: 3
Views: 31

Re: 2E.15

Since TeCl4 is see-saw shaped, I think that the angles are less than the ideal angles of 90 and 120 degrees. You're right that the lone pair will cause repulsion and distort the actual bond angles.
by Camellia Liu 1J
Wed Nov 13, 2019 7:49 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Sigma vs. Pi Bonds
Replies: 2
Views: 32

Re: Sigma vs. Pi Bonds

A sigma bond results from the an end-to-end overlap of atomic orbitals that forms a molecular orbital. Its shared electron density is directly between the bonding atoms and the electron density is continuous from one atom to the other. According to the textbook, sigma bond has no nodal planes contai...
by Camellia Liu 1J
Wed Nov 13, 2019 7:35 pm
Forum: *Particle in a Box
Topic: Hydrogen Atom
Replies: 7
Views: 113

Re: Hydrogen Atom

Another way to think about it is that when an atom absorbs a photon, the change in energy is positive because the electron absorbs the energy that the photon was carrying. This causes it to become excited to a higher energy state.
by Camellia Liu 1J
Thu Nov 07, 2019 4:18 pm
Forum: Lewis Structures
Topic: Octet rule exceptions?
Replies: 4
Views: 37

Re: Octet rule exceptions?

It's usually possible in periods 3 and beyond because they have an empty d-orbital (3d etc.) that allows them to accept those extra electrons.
by Camellia Liu 1J
Thu Nov 07, 2019 4:15 pm
Forum: Octet Exceptions
Topic: 2C.7
Replies: 2
Views: 32

Re: 2C.7

I always start by counting the number of electrons that I have to work with. For ICL2+, I counted 20 electrons, and since I is less electronegative than Cl, I placed it as the central atom. Then it comes down to placing the single bonds in and determining where the lone pairs go. For ICl2+, I got 2 ...
by Camellia Liu 1J
Thu Nov 07, 2019 4:09 pm
Forum: Lewis Structures
Topic: 2.7 Lewis structure for N5 +
Replies: 3
Views: 32

Re: 2.7 Lewis structure for N5 +

In a Lewis structure, I believe that you can show it as connected in a chain. To do the problem, I started by counting the electrons of N5+ and got 24e-. Then I placed them in a chain-formation and started rearranging the electrons and bonds to get the most optimal formal charge for each nitrogen at...
by Camellia Liu 1J
Thu Nov 07, 2019 4:00 pm
Forum: Coordinate Covalent Bonds
Topic: Elements that can form coordinate covalent bonds
Replies: 2
Views: 38

Re: Elements that can form coordinate covalent bonds

I think two factors that help determine whether or not an element forms coordinate covalent bonds is electronegativity and the octet rule. Atoms that accept the two electrons should be "hungry" enough to take them, but this can also mean that they don't have a complete electron shell. That...
by Camellia Liu 1J
Thu Nov 07, 2019 3:46 pm
Forum: Trends in The Periodic Table
Topic: Polarizability
Replies: 4
Views: 42

Re: Polarizability

Another way to think about it in terms of how tightly the electron is 'held' by the nucleus. The larger the ion, the more shielding the outer electrons experience, and so the easier it is to be polarized--to have its electron cloud distorted.
by Camellia Liu 1J
Thu Oct 31, 2019 4:16 pm
Forum: Resonance Structures
Topic: Difference between Resonance and Lewis structures
Replies: 5
Views: 38

Re: Difference between Resonance and Lewis structures

I'm not sure if resonance structures are limited to just double bonds--but I think that they are the most popular. Resonance is possible whenever a Lewis structure has a multiple bond and the other atom has at least one lone pair. Resonance structures have the same number of electrons and the same a...
by Camellia Liu 1J
Thu Oct 31, 2019 3:52 pm
Forum: Octet Exceptions
Topic: En
Replies: 3
Views: 35

Re: En

En stands for electronegativity, which is the electron pulling power of an atom.

For your second question, I think that in lecture it was said that for electronegativity differences between 2 and 1.5 it would depend on studying the particular characters of the atom/molecule/compound that you have.
by Camellia Liu 1J
Thu Oct 31, 2019 3:49 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge Calculation
Replies: 4
Views: 55

Re: Formal Charge Calculation

Formal charge indicates the gain or the loss of electrons of an atom in the formation of a covalent bond. To assign formal charge: Formal Charge = V - (L + ½ S) where V is the number of valence electrons in the free atom L is the number of electrons present on the bonded atom as lone pairs and S is ...
by Camellia Liu 1J
Thu Oct 31, 2019 3:42 pm
Forum: *Shrodinger Equation
Topic: shrodinger equation
Replies: 4
Views: 68

Re: shrodinger equation

Shrodinger's equation basically defines a wave function of a particle that has a certain value at any given time for certain points in space. It also helps specify how the waves are altered by external forces. The equation is HΨ=EΨ, where Ψ represents the height of a wave at position x, y, z and Ψ^2...
by Camellia Liu 1J
Thu Oct 31, 2019 3:40 pm
Forum: Photoelectric Effect
Topic: Threshold Energy
Replies: 5
Views: 74

Re: Threshold Energy

To add on, work function is the smallest amount of energy needed to remove an electron from a metallic surface while the threshold energy refers to the frequency required to release the electron from the surface. But essentially they both refer to the energy required to eject an electron from the me...
by Camellia Liu 1J
Fri Oct 25, 2019 11:20 am
Forum: Formal Charge and Oxidation Numbers
Topic: Electron Affinity and Formal Charge
Replies: 3
Views: 28

Re: Electron Affinity and Formal Charge

I think what he said was to not put negative (formal) charges on the element with the lower electron affinity (which is the central atom).
by Camellia Liu 1J
Fri Oct 25, 2019 11:19 am
Forum: Ionic & Covalent Bonds
Topic: Ionization Energy
Replies: 5
Views: 48

Re: Ionization Energy

Another way to think about it is that because ionization energy is the energy required to remove an electron from a gaseous atom/ion, you can understand it in terms of reactivity. The higher the ionization energy, the harder it is to remove an electron. So, as you go across a period, the atomic radi...
by Camellia Liu 1J
Fri Oct 25, 2019 11:12 am
Forum: Resonance Structures
Topic: Delocalization
Replies: 2
Views: 34

Delocalization

What does it mean when an electron is delocalized and how do you know when it is delocalized? What are the implications in double and triple bonds?
by Camellia Liu 1J
Thu Oct 24, 2019 5:59 pm
Forum: Properties of Light
Topic: photoelectric effect
Replies: 4
Views: 52

Re: photoelectric effect

I don't think intensity is related to either the frequency or the wavelength. When you double the intensity of light, you increase the number of photons emitted per second by the light source.
by Camellia Liu 1J
Thu Oct 24, 2019 5:55 pm
Forum: Resonance Structures
Topic: Different Resonance Structures
Replies: 4
Views: 43

Re: Different Resonance Structures

I'm not sure if different structures for the same molecule/compound necessarily have different energies. In the textbook, for NO3- specifically it mentioned that all three valid structures have the same energy. The bond lengths in a nitrate ion is also the same, and since they're identical, the best...
by Camellia Liu 1J
Thu Oct 24, 2019 5:45 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configuration p orbital
Replies: 2
Views: 30

Re: Electron Configuration p orbital

I think generally you can just leave it as p^n (whatever the number of electrons is) on tests if you understand how the electrons fit into the px, py, and pz orbitals. I'd know it just in case though.
by Camellia Liu 1J
Fri Oct 18, 2019 3:08 pm
Forum: Quantum Numbers and The H-Atom
Topic: Angular Momentum Quantum Number
Replies: 3
Views: 60

Re: Angular Momentum Quantum Number

The second quantum number l is the one associated with angular momentum, which determines the shape of the electron's orbital (the subshell).

The allowed values of l are: l= 0, 1, 2, ... n-1 where:
l=0 (s- orbital); l=1 (p-orbital); l=2 (d-orbital); l=3 (f-orbital)
by Camellia Liu 1J
Fri Oct 18, 2019 2:52 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Cr and Cu
Replies: 5
Views: 50

Re: Cr and Cu

Cr and Cu are exceptions because both of them come into a case where a more symmetric distribution of their electrons would allow them to become more stable. The Aufbau Principle says: Cr = [Ar] 4s2 3d4 Cu = [Ar] 4s2 3d9 But the actual configurations are: Cr= [Ar] 4s1 3d5 Cu = [Ar] 4s1 3d10 The shif...
by Camellia Liu 1J
Fri Oct 18, 2019 2:47 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Exceptions
Replies: 4
Views: 39

Re: Exceptions

I think that Cr and Cu are the main exceptions that we need to know and memorize--just to understand the concepts that completely filled sub levels are more stable than those that are partially fulled (basically that symmetry leads to stability). In regards to other exceptions, I think that Niobium:...
by Camellia Liu 1J
Fri Oct 18, 2019 2:39 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Hund's Rule
Replies: 3
Views: 32

Re: Hund's Rule

Hund's Rule basically says that before any two electrons can occupy an orbital in a subshell, the other orbitals in that same subshell have to be first occupied by one electron. It also states that the electrons filling the subshell will have parallel spin. When two electrons fill the shell, they wi...
by Camellia Liu 1J
Thu Oct 17, 2019 11:34 pm
Forum: Quantum Numbers and The H-Atom
Topic: Orbitals in an H-Atom
Replies: 3
Views: 46

Re: Orbitals in an H-Atom

Hydrogen atoms only have one electron in an s-orbital, so there is not really any electron-to-electron repulsion occurring to differentiate between the different s, p, d, and f orbitals. In atoms with multiple electrons, the interaction between the electrons causes variations in angular components a...
by Camellia Liu 1J
Sun Oct 13, 2019 4:17 pm
Forum: Properties of Electrons
Topic: Photons
Replies: 5
Views: 46

Re: Photons

Photons are regarded as packets of energy. The amount of energy in these photons can be calculated by E=hf, where E=energy of the photon in Joules, h= Planck's constant 6.63x10^-34 Joule-seconds, and f= frequency of the light in Hz. Photons are particles of light, so they can't have negative energie...
by Camellia Liu 1J
Sun Oct 13, 2019 3:24 pm
Forum: Properties of Electrons
Topic: Mass of Electrons
Replies: 6
Views: 37

Re: Mass of Electrons

I believe all electrons have the same mass. In J.J. Thomson's experiment involving cathode rays, he found that electrons were the same regardless of the metal that was used for the cathode. The mass of an electron I think is approximately 9.109x10^-31 kg or 5.489x10^-4 amu.
by Camellia Liu 1J
Sun Oct 13, 2019 3:18 pm
Forum: DeBroglie Equation
Topic: De Broglie's Equation
Replies: 4
Views: 76

Re: De Broglie's Equation

When De Broglie derived his equation, he didn't actually have any experimental data. Instead, he based it all on well-established theories and equations like Einstein's E=mc^2 and Planck's equation, E=hv. I don't think we usually use De Broglie's equation to apply to objects with very large masses. ...
by Camellia Liu 1J
Sun Oct 13, 2019 1:39 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Atomic Spectra for H
Replies: 5
Views: 42

Re: Atomic Spectra for H

I believe the equation is this one: En= -hR/n2, which you can use when you are trying to find the energy of the transitions between certain n levels. The Lyman (n=1), Balmer (n=2), Paschen (n=3), Brackett (n=4), and Pfund series (n=5) describes the spectrum of hydrogen.
by Camellia Liu 1J
Sun Oct 13, 2019 1:18 pm
Forum: Properties of Light
Topic: 1A.11
Replies: 3
Views: 39

Re: 1A.11

I'm pretty sure that its a result of experimental discovery. Electrons change energy levels in quantized values, and when it transitions between different levels, it emits or absorbs energy equal to the energy difference between the original state and the now-different state. The different series th...
by Camellia Liu 1J
Thu Oct 03, 2019 12:51 pm
Forum: Significant Figures
Topic: General sig figs question
Replies: 5
Views: 64

Re: General sig figs question

I'm pretty sure that you start by counting the number of sig figs in the decimal part of the number in the problem. You add or subtract normally and then you round the answer to the least number of places in the decimal part of your final answer. For multiplying/dividing, the least number of sig fig...
by Camellia Liu 1J
Thu Oct 03, 2019 12:11 pm
Forum: Limiting Reactant Calculations
Topic: Fundamentals M7
Replies: 3
Views: 43

Fundamentals M7

I found that Mg was the limiting reactant and that B2O3 was in excess by using the ratio 1:3 and finding that since we have approx 1795 moles of B2O3, we would need approx 5385mol of Mg. Since we only have 5143 mols of Mg, I concluded that it was the limiting reactant. Is there a faster/ more clear-...
by Camellia Liu 1J
Thu Oct 03, 2019 11:37 am
Forum: Limiting Reactant Calculations
Topic: Chemical Principles Section M Question 5b
Replies: 2
Views: 37

Re: Chemical Principles Section M Question 5b

I got the same answer: 12 mols ClO2 (looking at the ratio of 6 ClO2: 6 ClO2F) and 2 mols of Br2 (again, looking at the ratio 2BrF3: 1Br2). Since we know that BrF3 is the limiting reactant and that there are 4 mol of BrF3 needed for 12 mols ClO2, we know that we have 1 mol excess of BrF3 after 2 mole...
by Camellia Liu 1J
Thu Oct 03, 2019 12:38 am
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Different types of formulas
Replies: 2
Views: 64

Re: Different types of formulas

Chemical formulas basically show the symbols and the proportion/number of elements in a compound.

Molecular formulas show the number of each type of atom present in the molecule.

Structural formulas show the arrangement of atoms and the bonds between them.
by Camellia Liu 1J
Thu Oct 03, 2019 12:30 am
Forum: Molarity, Solutions, Dilutions
Topic: Fundamental G.13
Replies: 4
Views: 59

Re: Fundamental G.13

You would actually divide 0.2 by 4L, since the M1V1=M2V2 relationship would leave you with (1)(0.2) = (4)(M2). By doing that, you'd get M2 = 0.05 M NH4NO3. Then you can calculate the number of moles of NH4NO3 by solving 0.05 = (# of mols) / (0.1 L), which would give you 0.005 mols of NH4NO3. So the ...

Go to advanced search