Search found 51 matches

by Sion Hwang 4D
Tue Dec 03, 2019 12:00 pm
Forum: Air Pollution & Acid Rain
Topic: Formation of Acid Rain
Replies: 3
Views: 47

Re: Formation of Acid Rain

When potentially hazardous chemicals such as CO2, SO2, and NO2 are released into the air, these compounds are oxidized in the atmosphere and then act as acids when reacted with water vapor (i.e. clouds). Then, when it rains, these acidic compounds are released into soils, etc., which harm the enviro...
by Sion Hwang 4D
Tue Dec 03, 2019 11:55 am
Forum: Naming
Topic: [CO(SO4)(NH3)5]+
Replies: 2
Views: 20

Re: [CO(SO4)(NH3)5]+

In the coordination compounds, ligands are always named first alphabetically. There is a sulfate and ammonia in the sphere. Since a comes before s, ammonia will come first. Ammonia is called "Ammine" in coordination compounds, and sulfate is called "sulfato." Since there are 5 am...
by Sion Hwang 4D
Tue Dec 03, 2019 11:49 am
Forum: Naming
Topic: cations
Replies: 2
Views: 21

Re: cations

The coordination compound itself can be a cation, if it is bound to an anion such as: Coordination sphere + Cl2. If this molecule was neutral, the coordination sphere would have an overall charge of +2, because the 2 Cl's give a negative 2 charge. Hence, the central metal atom could have a +2 charge...
by Sion Hwang 4D
Tue Dec 03, 2019 11:44 am
Forum: Identifying Acidic & Basic Salts
Topic: HW 6D11
Replies: 7
Views: 90

Re: HW 6D11

The salts are not acidic until in a solution. In its natural, solid state, there is no dissociation of a proton (H+) from the molecule that makes a solution acidic. By the Arrhenius definition, acids are in an aqueous state, which is why there is water added to the metal salts. In coordination compo...
by Sion Hwang 4D
Tue Dec 03, 2019 11:36 am
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: weak acids/bases
Replies: 1
Views: 18

Re: weak acids/bases

I believe it would be important to memorize the weak acids and be able to explain why they are weak. For example, HF is a weak acid, but the other halogens are not weak acids when bonded to a hydrogen. You should be able to explain this. Knowing which acids are weak would also help you to explain wh...
by Sion Hwang 4D
Tue Nov 26, 2019 2:50 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Larger molecules
Replies: 3
Views: 33

Re: Larger molecules

I think we will be expected to know how to convert from the name to the formula (and vice versa) and ultimately use this information to create a Lewis structure (which can be constructed using knowledge on coordination compounds as well as formal charge).
by Sion Hwang 4D
Tue Nov 26, 2019 2:47 am
Forum: Hybridization
Topic: Hybridization of PF5
Replies: 4
Views: 31

Re: Hybridization of PF5

Each F atom has 4 electron domains (1 bonding with the P atom and 3 lone pairs). Meaning, the hybrid orbital would be sp3.
by Sion Hwang 4D
Tue Nov 26, 2019 2:41 am
Forum: Naming
Topic: Chelating Complex
Replies: 4
Views: 32

Re: Chelating Complex

Chelating compounds have a central metal atom that is attached to a ligand in a ring structure.
They are significant in biological systems, because the chelates' orientation allows it to bind much stronger to toxic metal ions than other molecules.
by Sion Hwang 4D
Tue Nov 26, 2019 2:35 am
Forum: Amphoteric Compounds
Topic: Oxides
Replies: 4
Views: 30

Re: Oxides

Basic oxides usually are located within the group 1 alkali and group 2 alkaline earth metals. Oxides that are located in the far right of the periodic table (next to the metalloids) are mostly acidic. Near the metalloids, there is a band of elements that are amphoteric. Meaning, when the central ato...
by Sion Hwang 4D
Mon Nov 25, 2019 9:32 pm
Forum: Dipole Moments
Topic: Dipole Moment
Replies: 10
Views: 89

Re: Dipole Moment

Can an individual molecule be dipole- dipole. Or would we just say that this is a dipole moment within 1 molecule? An individual molecule will only have a dipole moment. Dipole-dipole interaction can only occur between two molecules. This is because dipole-dipole is an intermolecular force, not an ...
by Sion Hwang 4D
Wed Nov 20, 2019 3:05 am
Forum: Dipole Moments
Topic: dipole moments vs dipole-dipole
Replies: 4
Views: 83

Re: dipole moments vs dipole-dipole

please reply to this by quoting my question so i get a notification. thanks in advance! what is the difference between dipole moments and induced dipoles and dipole-dipole interactions? From what I understand dipole moments are permanent dipoles within a molecule, between atoms (like C-F). Induced ...
by Sion Hwang 4D
Wed Nov 20, 2019 2:51 am
Forum: Dipole Moments
Topic: boiling point
Replies: 6
Views: 80

Re: boiling point

As you go down a group, the molar mass of each element, as well as the number of electrons within in each atom, increases. Hence, stronger dispersion forces can be created. Although HBr may have a greater difference in electronegativity than HI, iodine has a greater polarizability. This means that H...
by Sion Hwang 4D
Wed Nov 20, 2019 2:39 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Instantaneous Dipole Moment
Replies: 4
Views: 29

Re: Instantaneous Dipole Moment

Instantaneous dipole moments occur in any molecules. This is because within a molecule, electrons are not fixed to a certain position or trajectory (as we have seen with the wave functions). We really cannot tell where an electron will be, and its movement is "instantaneous." Hence, at a r...
by Sion Hwang 4D
Wed Nov 20, 2019 2:34 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Ionic Bonds
Replies: 4
Views: 23

Re: Ionic Bonds

Ionic bonds occur when the difference in electronegativity between two atoms is greater than 2.0. They usually occur between metals and nonmetals, as the difference in electronegativity allows this to happen. However, some transition metals can form ionic bonds, depending on their oxidation state. I...
by Sion Hwang 4D
Wed Nov 20, 2019 2:29 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Can linear molecular shapes have lone pair?
Replies: 4
Views: 30

Re: Can linear molecular shapes have lone pair?

Linear molecules can have lone pairs. The VSEPR formula for all linear molecules are: AX2, AX2E3, and AX2E4. The definition of a linear molecule is that it is arranged perfectly at a angle of 180 degrees. Anything less than that would be considered an angular (or bent) molecule. How does this happen...
by Sion Hwang 4D
Wed Nov 13, 2019 5:26 pm
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: Intramolecular forces
Replies: 2
Views: 38

Re: Intramolecular forces

Intramolecular forces are forces that hold a molecule together (bonding between atoms). Generally, polar and nonpolar covalent bonds within a molecule fall under the general umbrella of "covalent bonds/intramolecular forces." There are two other intramolecular forces: ionic bonding, which ...
by Sion Hwang 4D
Wed Nov 13, 2019 5:22 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Sulfur Hexafluoride VSEPR
Replies: 3
Views: 25

Re: Sulfur Hexafluoride VSEPR

When considering VSEPR, you always have to look at the central atom. In SF6, the central atom is sulfur, and there are 6 flourines singly-bonded to it. There are no lone pairs. The formal charges are all 0, so this is the most stable state of the atom. For the shape itself in 3D, the electron pairs ...
by Sion Hwang 4D
Wed Nov 13, 2019 5:16 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Will we need to know these VSEPR shapes as well?
Replies: 10
Views: 79

Re: Will we need to know these VSEPR shapes as well?

Those models are added in once we learn how lone pairs affect the arrangement of atoms within a molecule. For example, in H2O, there are two lone pairs on the oxygen and two bonding pairs. The two long pairs will repulse the bonded H and cause the shape of a water molecule to be bent. Hence, the cla...
by Sion Hwang 4D
Wed Nov 13, 2019 3:45 pm
Forum: Dipole Moments
Topic: Dipole Moments
Replies: 4
Views: 31

Re: Dipole Moments

All of these molecules have a central C atom bonded to hydrogen atom(s) and Cl atom(s). There is a dipole moment due to the difference in electronegativity between Cl and C. The difference in electronegativity between C and Cl is large enough that it is a polar covalent bond. This means that there w...
by Sion Hwang 4D
Wed Nov 13, 2019 3:42 pm
Forum: Dipole Moments
Topic: 3F.1
Replies: 2
Views: 35

Re: 3F.1

All molecules exert disperson (London) forces. This is because electrons are not "fixed" to a certain atom or orientation within the molecule at all times. They move around freely (as revealed by wave functions). This means that at any moment, there could be a greater concentration of elec...
by Sion Hwang 4D
Mon Nov 04, 2019 12:26 pm
Forum: Bond Lengths & Energies
Topic: 2D.19
Replies: 2
Views: 33

Re: 2D.19

You dont need to calculate bond lengths; they are experimentally calculated. I imagine that if this was to come up on the test, you will have the covalent radii given and you will just need to add them together to calculate bond length.
by Sion Hwang 4D
Mon Nov 04, 2019 12:23 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge/Lewis structures
Replies: 5
Views: 34

Re: Formal Charge/Lewis structures

For covalent compounds, you always want to make sure that the central atom has a formal charge of 0 (or close to it). This makes the compound most stable. For ionic compounds, ions share electrons unequally, so the charges should be different (opposite in sign) anyways.
by Sion Hwang 4D
Mon Nov 04, 2019 12:06 pm
Forum: Ionic & Covalent Bonds
Topic: Electron Configuration
Replies: 2
Views: 18

Re: Electron Configuration

The energy levels increase in order: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p... and you don't have to worry about the f-orbitals, which are lanthanides and actinides. The electrons will fill up in this order. However, you must remember that while an empty 3d orbital is higher ine energy than 4s, ...
by Sion Hwang 4D
Mon Nov 04, 2019 11:59 am
Forum: Electronegativity
Topic: Electronegativity Ex.
Replies: 2
Views: 24

Re: Electronegativity Ex.

Remember that ionic bonds themselves have a greater difference in electronegativities between the atoms than covalent bonds. This is because the greater the electronegativity, the more unequally shared the electrons are between two atoms, and the more chance the two atoms become ions. H and cl have ...
by Sion Hwang 4D
Mon Nov 04, 2019 11:55 am
Forum: Octet Exceptions
Topic: octet exceptions
Replies: 11
Views: 106

Re: octet exceptions

Elements that are period 3 and beyond in the periodic table have access to the d-orbitals, which can fill up to 10 extra valence electrons. One example of this is SF6, where sulfur has 6 bonds to each fluorine atom and thus has 12 valence electrons. Some elements, such as B and Al can have incomplet...
by Sion Hwang 4D
Mon Oct 28, 2019 5:30 pm
Forum: Lewis Structures
Topic: Resonance Structures
Replies: 2
Views: 22

Re: Resonance Structures

Chlorine already has 7 valence electrons, whereas oxygen has six. So chlorine only needs one more electron shared in order to make it stable. The optimal lewis structure that makes this molecule most stable would be to put a double bond with the oxygen.
by Sion Hwang 4D
Mon Oct 28, 2019 5:23 pm
Forum: Octet Exceptions
Topic: expanded octet?
Replies: 9
Views: 69

Re: expanded octet?

They're in period 3, which means that they have access to the 3d orbital. This orbital can accommodate extra orbitals, so these atoms can have over 8 valence electrons.
by Sion Hwang 4D
Mon Oct 28, 2019 5:21 pm
Forum: Lewis Structures
Topic: valence electron counting
Replies: 2
Views: 25

Re: valence electron counting

Bromine has access to the d orbital, since it is in the fourth period. Therefore, it can accommodate extra electrons in that orbital. Thus, it will have 2 sets of lone pairs, adding to 28 electrons total.
by Sion Hwang 4D
Mon Oct 28, 2019 4:43 pm
Forum: Resonance Structures
Topic: HW Question 2B9
Replies: 3
Views: 26

Re: HW Question 2B9

These bonds are polyatomic. It is made up of many atoms, or separate molecules. Each bracket is like a separate molecule, and the charges ultimately cancel out to become 0 charged.

For part b, K3P is polyatomic and is an ionic bond. It is made of many polyatomic ions.
by Sion Hwang 4D
Mon Oct 28, 2019 4:37 pm
Forum: Lewis Structures
Topic: 2B- #9 sodium hypochlorite
Replies: 1
Views: 17

Re: 2B- #9 sodium hypochlorite

The hypochlorite atom has a negative 1 charge, meaning that it has gained an electron from the sodium atom. Remember, ionic bonding is giving and losing electrons. Hence, the sodium "gives" its electron to the hypochlorite atom and thus becomes a full valence shell. By gaining an electron,...
by Sion Hwang 4D
Tue Oct 22, 2019 3:43 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Hw Help 1D.25
Replies: 3
Views: 30

Re: Hw Help 1D.25

You can check by seeing if the subshell exists, as l=0 through n-1. (a) 2d has an n value of 2. Therefore, l can either be 0 or 1, which corresponds to the s and p subshells. Notice that d is not a part of the angular momentum quantum number, so a) cannot exist. (b) 4d has an n value of 3. l can be ...
by Sion Hwang 4D
Tue Oct 22, 2019 3:37 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: n,l,ml,and ms
Replies: 2
Views: 30

Re: n,l,ml,and ms

These variables are all quantum numbers of atoms, describing where you might be able to find electrons in an atom. n is the principle quantum number, which describes the energy and size of the atom, or how many shells the atom has. In other words, it tells of how distant electrons are from the nucle...
by Sion Hwang 4D
Tue Oct 22, 2019 3:10 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: d orbital
Replies: 3
Views: 40

Re: d orbital

The d orbitals begin appearing at the fourth row on the periodic table, beginning with the 3d orbital. Starting from the first transition metal, scandium, electrons fill the 3d orbital, and the ground state of scandium is [Ar]4s23d1. However, when we reach chromium, this trend changes. Instead of [A...
by Sion Hwang 4D
Tue Oct 22, 2019 2:48 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Orbitals
Replies: 5
Views: 38

Re: Orbitals

If n=6, there are indeed n-1 subshells (l).
These would be the s, p, d, f, and g subshells.
For ml, these are all values from -l to +l.
by Sion Hwang 4D
Tue Oct 22, 2019 2:45 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Energy of Electrons
Replies: 6
Views: 45

Re: Energy of Electrons

The electron is at a higher energy state, because electrons move up the orbital level when they are excited by an external energy source.
The electrons can move down energy orbitals by releasing energy in the form of a photon.
by Sion Hwang 4D
Tue Oct 15, 2019 5:56 pm
Forum: DeBroglie Equation
Topic: 1B.9 HW Question
Replies: 8
Views: 83

Re: 1B.9 HW Question

You have the light on for two seconds. Meaning, the total energy output will be 64J. Then, you can use the equation: E = hc/λ. H and c are known constants. The wavelength of violet light is also given, but remember to convert nm to m. Then, find the E, which is the energy per photon. Take total ener...
by Sion Hwang 4D
Tue Oct 15, 2019 5:48 pm
Forum: *Shrodinger Equation
Topic: What is Shrodinger's for?
Replies: 6
Views: 48

Re: What is Shrodinger's for?

Schrodinger's equation predicts future dynamic systems via calculating the partial differentiation of wave functions, or how the electron will behave around its nucleus. Most likely, you will not have to calculate anything with the equation itself, but you should at least know what each part of the ...
by Sion Hwang 4D
Tue Oct 15, 2019 5:43 pm
Forum: DeBroglie Equation
Topic: HW 1b.15 part c
Replies: 2
Views: 21

Re: HW 1b.15 part c

Photons are quantized and are particles.
You can't use the c=vλ equation, because that is an equation used for the wave model.
You must use E=hc/λ.
by Sion Hwang 4D
Tue Oct 15, 2019 5:39 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Principle Quantum Level
Replies: 2
Views: 30

Re: Principle Quantum Level

You can use the Rydberg equation, and isolate for n-initial. The equation states: v=R((1/ni^2)-(1/nf^2)), where v=1.14 x 10^14 s^-1, nf=4 (given). Rearranging to isolate ni, we get: (v/R) + (1/nf^2) = 1/ni^2. Plugging in the values, we get: (1.14x10^14 s^-1 / 3.29x10^15) + (1/4^2) = 1/ni^2. ni=sqrt(...
by Sion Hwang 4D
Tue Oct 15, 2019 5:24 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: 1B.27 Hw Help
Replies: 5
Views: 49

Re: 1B.27 Hw Help

You use the Heisenberg's Uncertainty Equation.

It states:
ΔmΔvΔx ≥ h/4pi.
You know that the mass is 8.00 kg, h= 6.626 x 10^-34 kg*m^2*s^-1, and Δv is 10m/s. You must isolate Δx.

Hence,

Δx ≥ (6.626 x 10^-34 kg*m^2*s^-1 / 4pi) / (8kg * 10m/s), and you are left with:
Δx ≥ 6.6 x 10^-37 m.
by Sion Hwang 4D
Tue Oct 15, 2019 5:12 pm
Forum: Properties of Light
Topic: HW Question 1A.15
Replies: 2
Views: 37

Re: HW Question 1A.15

Atomic hydrogen has a Lyman series at n=1 for the ultraviolet spectrum. Hence, that will be the initial energy level. Using the wavelength given, use the equation v=c/lambda to find frequency of the final energy level. v=2.998 x 10^8 ms^-1 / 102.6 x 10^-9, since wavelength is given in nm but you nee...
by Sion Hwang 4D
Tue Oct 08, 2019 6:15 pm
Forum: Properties of Light
Topic: 1A.11 Question on Balmer and Lyman series
Replies: 2
Views: 37

Re: 1A.11 Question on Balmer and Lyman series

Balmer and Lyman series are a series of spectral line emissions in hydrogen atoms.
Each absorption line (each series) is the quantum number of the lower energy level (n=1 through 6).
These spectral lines are caused by electrons crossing between two levels of energy, producing light.
by Sion Hwang 4D
Tue Oct 08, 2019 5:08 pm
Forum: Limiting Reactant Calculations
Topic: Theoretical yield
Replies: 5
Views: 89

Re: Theoretical yield

You multiply the amount of moles produced by the molar mass.
Hence, 0.20 mol x 81 g/mol = 16.2 g of product.
by Sion Hwang 4D
Tue Oct 08, 2019 5:05 pm
Forum: Balancing Chemical Reactions
Topic: Question about hydroxide
Replies: 5
Views: 82

Re: Question about hydroxide

If you look on the periodic table, Calcium is located on the 2nd column. This means that Ca has two valence electrons, causing it to have a positive 2 charge as an ion. OH, hydroxide, has a negative 1 charge. In order to balance the charge, there must be 2 OH ions for every Ca ion. Hence, you have C...
by Sion Hwang 4D
Tue Oct 08, 2019 4:58 pm
Forum: Properties of Light
Topic: Wave and Photon Models
Replies: 2
Views: 36

Re: Wave and Photon Models

I think you mean wave vs. particle models for light? Light can be viewed with a wave model, where an electric field generates a changing magnetic field. Light reflects and refracts like other waves. Photons can be seen as packets of energy (quanta) or individual particles. Different situations call ...
by Sion Hwang 4D
Tue Oct 08, 2019 4:37 pm
Forum: Photoelectric Effect
Topic: Quanta and Photons
Replies: 3
Views: 53

Re: Quanta and Photons

Quanta is a discrete quantity of energy. Meaning, quanta can represent energy as individual packets.
A photon is a quantum of light, and photons can be seen as packets of light energy.
So, there is a pretty similar relationship between quanta and photons.
by Sion Hwang 4D
Thu Oct 03, 2019 1:32 am
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Fundamental E. 15 Question...
Replies: 3
Views: 43

Re: Fundamental E. 15 Question...

Anything with "sulfide" means that there are negatively charged sulfur ions in the compound (S ^ -2). Since the unknown metal has two hydroxide ions associated with it in the problem, we know that the metal must have a positive 2 charge. Hence, only 1 sulfur ion would need to be attached t...
by Sion Hwang 4D
Thu Oct 03, 2019 1:26 am
Forum: Balancing Chemical Reactions
Topic: Question L35
Replies: 2
Views: 51

Re: Question L35

I believe you wrote the final equation wrong. It is supposed to be Fe3Br8 + Na2CO3 --> NaBr + CO2 + Fe3O4. With this equation, the Fe's are already balanced on both sides. Thus, you would seek to balance the Br, multiplying NaBr by 8. You will get: Fe3Br8 + Na2CO3 --> 8NaBr + CO2 + Fe3O4. Now, you m...
by Sion Hwang 4D
Thu Oct 03, 2019 1:17 am
Forum: Properties of Light
Topic: EM Spectrum
Replies: 4
Views: 50

Re: EM Spectrum

I don't believe that you will have to memorize the whole EM spectrum (as in all of the numbers, different wavelengths, etc.). However, you will most likely need to understand what the spectrum depicts, how it depicts it, and what it infers about different wavelengths of light and such. It is importa...
by Sion Hwang 4D
Thu Oct 03, 2019 1:10 am
Forum: Significant Figures
Topic: Sig figs confusion
Replies: 8
Views: 120

Re: Sig figs confusion

Your final answer cannot be more precise than the measurements taken and given.
Generally, however, if the problem does not specifically indicate any measurement with significant figures, I would go with two numbers after the decimal (i.e. 35.45 or 2.15).
by Sion Hwang 4D
Thu Oct 03, 2019 1:02 am
Forum: SI Units, Unit Conversions
Topic: Unit Conversions
Replies: 11
Views: 125

Re: Unit Conversions

You will have to use Avogadro's number, which states that 1 mol of a substance contains 6.022 x (10^23) atoms of it. Thus, you take however many (x) mols you have, and multiply it to Avogadro's number. Thus, you have the equation: x mol * (6.022 x (10^23) atoms / mol), which cancels the mols out and...

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