Search found 53 matches

by EvaLi_3J
Sun Dec 08, 2019 9:52 am
Forum: Hybridization
Topic: lone pairs in hybridization
Replies: 6
Views: 121

Re: lone pairs in hybridization

One lone pair would normally take up one hybridized orbital, just like the bonding pairs.
by EvaLi_3J
Sun Dec 08, 2019 9:48 am
Forum: Dipole Moments
Topic: test 2 #6
Replies: 2
Views: 100

Re: test 2 #6

Professor said in class that only when all the surrounding atoms are the same, would the tetrahedral molecules be non-polar.
by EvaLi_3J
Sun Dec 08, 2019 9:47 am
Forum: Dipole Moments
Topic: Cancelling dipole moments
Replies: 9
Views: 181

Re: Cancelling dipole moments

You don't have to determine whether it is polar or not by trying to cancel every single dipole moment. If there is no lone pair on the central atom and all the other atoms are the same, it is a non-polar atom. If there are two opposite lone-pairs and all the other atoms are the same, it is probably ...
by EvaLi_3J
Sun Dec 08, 2019 9:44 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: LDF
Replies: 4
Views: 126

Re: LDF

Yes. London forces exist among all molecules. A induced dipole occurs on non-polar molecules that got close to polar molecules. The uneven electronic distribution in unpolar molecules would change the distribution of electrons in non-polar molecules.
by EvaLi_3J
Sun Dec 08, 2019 9:39 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: Hydrogen
Replies: 3
Views: 111

Re: Hydrogen

Normally you would just count the number of bonds (double and triple count as one) in the molecule.
by EvaLi_3J
Sun Nov 24, 2019 11:41 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Seesaw shape
Replies: 5
Views: 46

Seesaw shape

Can anyone please explain why the seesaw shape would occur? In what circumstance would it appear?
by EvaLi_3J
Sun Nov 24, 2019 11:37 pm
Forum: Trends in The Periodic Table
Topic: Octet Expansion
Replies: 3
Views: 109

Re: Octet Expansion

Starting from period 3, elements have the chance to expand their octets. Because in period three, electron orbitals go up to 3d.
by EvaLi_3J
Sun Nov 24, 2019 12:18 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Non-polar atoms with lone pairs
Replies: 4
Views: 37

Non-polar atoms with lone pairs

If a molecule has 1 lone pair, is it ever gonna be non-polar?
If it has 2 lone-pairs, can it be non-polar, since the lone pairs could possibly cancel each other?
If it has 3, 4, 5..., can it still be non-polar?
by EvaLi_3J
Sun Nov 24, 2019 12:16 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Non-polar molecules with different non-central atoms
Replies: 3
Views: 37

Non-polar molecules with different non-central atoms

If a molecule has one central atom with no lone pairs, four other atoms with two of them being the same, and the other two being the same (central atom + 2 A atoms + 2 B atoms, five atoms in total in this molecule.), would it still be a non-polar molecule? In other words, even though we have two dif...
by EvaLi_3J
Sun Nov 24, 2019 12:04 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bent vs linear
Replies: 56
Views: 750

Re: Bent vs linear

A molecule would be bent because it has lone pairs on the central atom. Lone pairs have very strong electronic repulsion, for which the other two atoms bonded to the central atom are repelled to be as far from the lone pair as possible.
by EvaLi_3J
Sun Nov 17, 2019 6:08 pm
Forum: Dipole Moments
Topic: SCl4 Molecule
Replies: 5
Views: 44

Re: SCl4 Molecule

There is a lone pair on the S atom, which makes this a polar atom overall. The Cl atoms are not directly opposite from each other, and that's why their dipole moments don't cancel.
by EvaLi_3J
Sun Nov 17, 2019 6:02 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR repulsion model
Replies: 8
Views: 75

Re: VSEPR repulsion model

Repulsion plays a large role. It determine both the general arrangement of the atoms in molecules and the specific angles between bonds. Repulsion makes it important that electron clouds are located as far from each other as possible.
by EvaLi_3J
Sun Nov 17, 2019 5:55 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Dipole moment
Replies: 5
Views: 44

Dipole moment

Can anyone please explain what exactly is dipole moment again? Why is it called "moment"?
by EvaLi_3J
Sun Nov 17, 2019 5:53 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: repulsion strength
Replies: 5
Views: 35

Re: repulsion strength

Lone pair and lone pair have the largest repulsion
Lone pair and bonding pair have the second largest repulsion
Bonding pair and bonding pair have the least repulsion
by EvaLi_3J
Fri Nov 15, 2019 12:53 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: 3F problem 3
Replies: 3
Views: 48

3F problem 3

For which of the following molecules will dipole–dipole interactions
be important: (a) CH4; (b) CH3Cl; (c) CH2Cl2; (d) CHCl3;
(e) CCl4?


Can anyone please explain this for me? I don't quite understand the differences between these for types of molecules.
by EvaLi_3J
Thu Nov 07, 2019 1:05 pm
Forum: Lewis Structures
Topic: Exceptions to the Octet Rule Question
Replies: 5
Views: 63

Re: Exceptions to the Octet Rule Question

Any element in and after the third period could have exceptions. The way you deal with the exceptions while drawing Lewis structure is basically make each atom an octet firstm and then attach the extra electrons onto the "exception atoms".
by EvaLi_3J
Thu Nov 07, 2019 1:02 pm
Forum: Lewis Structures
Topic: Does the shape that I draw the Lewis structure matter?
Replies: 14
Views: 113

Re: Does the shape that I draw the Lewis structure matter?

Currently, I don't think that it does, as we have not gone over the shape part yet.
by EvaLi_3J
Thu Nov 07, 2019 1:00 pm
Forum: Ionic & Covalent Bonds
Topic: Covalent and Ionic Bonds
Replies: 6
Views: 63

Re: Covalent and Ionic Bonds

I guess the most formal ways to explain them is looking at the differences between the electronegativity values for atoms that bond together. If two atoms have their electronegativity values differ by more than 2, they are more ionic. If less than 1.6, they are more covalent.
by EvaLi_3J
Thu Nov 07, 2019 12:57 pm
Forum: Ionic & Covalent Bonds
Topic: C, N, O, and F
Replies: 13
Views: 154

Re: C, N, O, and F

Yes, I believe they have to follow the octet rule as they can only have valence electrons as many as eight. Formal charges definitely don't have to be 0, even though the formal charges that are close to 0 makes the molecule more stable.
by EvaLi_3J
Thu Nov 07, 2019 12:54 pm
Forum: Ionic & Covalent Bonds
Topic: Why is the ionization energy of nitrogen higher than that of oxygen's?
Replies: 11
Views: 132

Re: Why is the ionization energy of nitrogen higher than that of oxygen's?

Draw the electronic configuration of the two atoms and you will see that Nitrogen has a half-full 2p shell. This makes it more stable than other unfull 2p shells.
by EvaLi_3J
Thu Nov 07, 2019 12:51 pm
Forum: Ionic & Covalent Bonds
Topic: Covalent character and ionic character
Replies: 5
Views: 50

Covalent character and ionic character

Can anyone please explain the difference plz?
by EvaLi_3J
Sun Nov 03, 2019 11:03 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: When would 3d orbital be filled before the 4s orbital?
Replies: 6
Views: 63

When would 3d orbital be filled before the 4s orbital?

When would 3d orbitals be filled before the 4s orbital?
And similarly, when would 4d filled before 5s? 4f before 6s?

I am just kind of confused as for what exactly is the order in which we fill our electrons into the orbitals. Obviously, there are quite some exceptions.
by EvaLi_3J
Sat Nov 02, 2019 9:35 pm
Forum: Ionic & Covalent Bonds
Topic: The Lewis structure for the chlorite ion ClO2- (Cl atom, 2 oxygen atoms, and one negative charge)
Replies: 1
Views: 19

The Lewis structure for the chlorite ion ClO2- (Cl atom, 2 oxygen atoms, and one negative charge)

Seems like Cl is the central atom and two oxygen atoms are both connected to it. Oxygens only have 6 outer electrons, but in the lewis structure on the book, seems like one of the oxygen atom does not have any electrons contributed to covalent bonding? You can find it on page 80 (topic 2B). When wou...
by EvaLi_3J
Sat Nov 02, 2019 9:27 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Exceptions in electronic configurations?
Replies: 3
Views: 45

Re: Exceptions in electronic configurations?

The exceptions to electron configurations are Chromium and Copper. Basically, in these two elements, you do not fill up the 4s shell first. Instead, you put one electron into the 4s shell and then move on to the 3d shell. So Cr's electron configuration is [Ar] 3d5 4s1 and Cu is [Ar] 3d10 4s1. The w...
by EvaLi_3J
Sat Nov 02, 2019 9:05 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Exceptions in electronic configurations?
Replies: 3
Views: 45

Exceptions in electronic configurations?

Does anyone know which atoms are the exceptions for electronic configuation?
And why are they exceptions?
by EvaLi_3J
Sat Nov 02, 2019 9:02 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: 2A problem 5
Replies: 2
Views: 26

Re: 2A problem 5

The answer is [Ar]3d10 because even though the 4s block on the periodic table is seen before the 3d block, 3d is still a shell below 4s and therefor the 3d shell would fill up before you could add any electrons to the 4s orbital. Because Cu+ has 28 valence electrons and you know that it comes after...
by EvaLi_3J
Sat Nov 02, 2019 8:33 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: 2A problem 5
Replies: 2
Views: 26

2A problem 5

On the textbook, this problem asks us to write the electronic configuration of Cu+, Bi3+, Ga3+, and Tl3+. Except for Bi3+, the other three ions seem to be exceptions to the energy level rule. Can anyone explain why that happened? For example, for Cu+, I wrote [Ar]3d33p54s2, but the answer is [Ar]3d1...
by EvaLi_3J
Sat Nov 02, 2019 4:01 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: How do we draw the electron configurations for transition metal atoms?
Replies: 2
Views: 53

How do we draw the electron configurations for transition metal atoms?

On the textbook 2A exercise 1, we are asked to write the valence electron of Sb, and the answer is 5. I thought that it would be 15. Can anyone explain why the valence electron is 5 and explain the electronic configuration of transition atoms in general?
by EvaLi_3J
Sat Nov 02, 2019 2:27 pm
Forum: Ionic & Covalent Bonds
Topic: coulomb potential energy and Madelung constant, as well as lattice energy
Replies: 4
Views: 57

coulomb potential energy and Madelung constant, as well as lattice energy

Are we supposed to know these concepts and equations for midterms and finals?

If yes, can someone explain how the lattice energy works please?
by EvaLi_3J
Sat Nov 02, 2019 1:55 pm
Forum: Ionic & Covalent Bonds
Topic: The net energy decrease when Na and Cl form NaCl
Replies: 2
Views: 37

The net energy decrease when Na and Cl form NaCl

On the book P72 (2A.3),it is said that "In summary, there is a net lowering of energy below that of the individual atoms, provided the net attraction between ions is greater than the energy needed to make them. The major contribution to the energy input is normally the ionization energy of the ...
by EvaLi_3J
Sun Oct 27, 2019 3:29 pm
Forum: Lewis Structures
Topic: Lone pair
Replies: 8
Views: 51

Lone pair

Can anyone please explain what a lone pair is? Is it just the valence electrons that have not been used in bonding?
by EvaLi_3J
Sun Oct 27, 2019 3:25 pm
Forum: Electronegativity
Topic: Difference between electronegativity, ionization energy, and electron affinity
Replies: 5
Views: 49

Re: Difference between electronegativity, ionization energy, and electron affinity

Electronegativity is a property that describes how easily it is for an atom to gain electrons to form bonds.
Ionization energy is THE ENERGY it takes for an electron to leave an atom.
Electron affinity is also THE ENERGY that would be released when an electron is added to a neutral atom or molecule.
by EvaLi_3J
Sun Oct 27, 2019 3:15 pm
Forum: Trends in The Periodic Table
Topic: Ionization and Electron Affinity
Replies: 5
Views: 72

Re: Ionization and Electron Affinity

Ionization energy represents the energy needed to REMOVE one electron from the atom, which is a representation of how easily the atom loses electrons. Electron affinity is the opposite. It measure how easily an atom GAINs electrons. The trends for these two properties are mostly opposite on the peri...
by EvaLi_3J
Sun Oct 27, 2019 3:13 pm
Forum: Ionic & Covalent Bonds
Topic: Resonance
Replies: 10
Views: 95

Resonance

So if these is resonance for a specific molecule, does it mean that there are three slightly different structures that exist for this one molecule? Or it just means that we can write its Lewis structure in three different ways?
by EvaLi_3J
Sun Oct 27, 2019 3:11 pm
Forum: Ionic & Covalent Bonds
Topic: Benzene's covalent bond
Replies: 2
Views: 33

Benzene's covalent bond

Can anyone explain again what's special about Benzene's chemical bonds? Is it a case of resonance?
by EvaLi_3J
Sun Oct 20, 2019 9:16 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Summary of how to write electron configurations please
Replies: 2
Views: 23

Re: Summary of how to write electron configurations please

I will try to be as comprehensive as possible, but if I missed anything, please correct me :) 1. know how many electrons this specific atom has 2. know the order in which subshells are filled 3. know how many electrons a specific subshell can take, for example, s has one orbital and can take 2 elect...
by EvaLi_3J
Sun Oct 20, 2019 9:07 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Why is 4s before 3d?
Replies: 9
Views: 108

Re: Why is 4s before 3d?

Because 4s has lower energy than 3d. There are some exceptions like this where higher energy level subshells are actually filled first.
by EvaLi_3J
Sun Oct 20, 2019 11:56 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron configurations for Ni and Sc
Replies: 1
Views: 23

Electron configurations for Ni and Sc

In the lecture, professor wrote the two electron configuration:
Ni: [Ar]3d8 4s2
Sc: [Ar]3d1 4s2

Can anyone please explain why 3d is filled with 8 and 1 electron in these two cases?
by EvaLi_3J
Sun Oct 20, 2019 11:52 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Exceptions for Electron Configuration
Replies: 6
Views: 45

Exceptions for Electron Configuration

In the lecture on Friday 10/18, professor mentioned how there exists EXCEPTIONS that half full d subshells and full d subshells have lower energy. Does anyone remember what this is exception to?
by EvaLi_3J
Sun Oct 20, 2019 11:49 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: electrostatic attraction
Replies: 1
Views: 28

electrostatic attraction

Can anyone please explain what electrostatic potential energy is? Ane how would it affect the interaction of electrons and atoms?
by EvaLi_3J
Sun Oct 20, 2019 11:39 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: The order in which subshells are filled
Replies: 3
Views: 39

The order in which subshells are filled

Can anyone please explain why some subshells in higher energy levels are filled earlier than those in lower energy levels?
by EvaLi_3J
Sun Oct 20, 2019 11:36 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Orbitals with different levels of energy
Replies: 1
Views: 20

Orbitals with different levels of energy

I'm a little confused as to how we should write electron configurations. I know that subshells in lower energy levels are sometimes filled after the higher energy level subshells. But as professor Lavelle said, we should still write it from lower energy levels to higher energy levels and from s to p...
by EvaLi_3J
Sun Oct 20, 2019 11:29 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Unpaired electrons
Replies: 1
Views: 9

Unpaired electrons

Can anybody please explain what unpaired electrons are? When would there be unpaired electrons?
by EvaLi_3J
Thu Oct 17, 2019 9:52 pm
Forum: Properties of Light
Topic: atomic spectra module
Replies: 1
Views: 30

Re: atomic spectra module

First, you can calculate the wavelength. Since you know that one meter is composed of 1,650,763.73 wavelengths of radiation emitted by krypton-86, you can basically divide one meter by this number, and you get the length of one wavelength. In terms of region, you can just check the spectrum and see ...
by EvaLi_3J
Thu Oct 17, 2019 9:47 pm
Forum: Properties of Light
Topic: Problem 1A.7
Replies: 5
Views: 82

Re: Problem 1A.7

A) Just use the equation c = wavelength * frequency. All light (including those that we cannot see like infrared and ultraviolet) have the same velosity, which is denoted by c, and it is equal to 3.0*10^8 m/s (this is not the more precise though, you might need to look up the precise value for preci...
by EvaLi_3J
Thu Oct 17, 2019 9:42 pm
Forum: Properties of Electrons
Topic: Wave Function
Replies: 5
Views: 122

Wave Function

Can anyone please explain the wave function to me again? I'm still kind of confused as for how the function is used. Does the wave function correspond to the the s, p, d ... orbitals we are talking about in the lecture?
by EvaLi_3J
Wed Oct 16, 2019 9:32 pm
Forum: Properties of Electrons
Topic: The wave property of electrons [ENDORSED]
Replies: 2
Views: 53

The wave property of electrons [ENDORSED]

Could anyone explain the wave property of electrons again?
Why does electrons have wave-like property? I know that through the diffraction experiment, we have proven that electrons have wavelike properties, but why could this experiment show this?


Thank you!
by EvaLi_3J
Wed Oct 16, 2019 9:27 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: What does the "x" indicate in (i.e.) the 2px state? [ENDORSED]
Replies: 5
Views: 50

Re: What does the "x" indicate in (i.e.) the 2px state? [ENDORSED]

I believe that x just means the x plane. Because the orbitals are 3D models, so we have x, y, and z planes. There could be multiple p orbitals in one atom, and they are normally arranged in different directions. To distinguish them, we use x to indicate the one that goes along the direction of the x...
by EvaLi_3J
Tue Oct 15, 2019 9:59 pm
Forum: DeBroglie Equation
Topic: Energy = mv^2
Replies: 2
Views: 66

Energy = mv^2

Hi! I remember in class professor Lavelle talked about how we could derive E = mv^2 from E = mc^2. I'm just not entirely sure about this equation. Is E = mv^2 applicable in any cases? For example, if I want to calculate the total energy of a moving baseball, can I use this equation? Also, since Kine...
by EvaLi_3J
Tue Oct 15, 2019 9:32 pm
Forum: DeBroglie Equation
Topic: Calculating Wavelength
Replies: 5
Views: 86

Re: Calculating Wavelength

Hi! I haven't done this problem before but I think what it means is that after you calculate the difference of the wavelengths (between protons and neutrons), you need to then calculate how much of the wavelength of neutron does this difference in wavelengths take up. Namely, diff divide by waveleng...

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