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by MKearney_4G
Sun Dec 08, 2019 4:38 pm
Forum: Resonance Structures
Topic: Molecules with resonance
Replies: 4
Views: 221

Re: Molecules with resonance

It really depends on if the conjugate base is stable (forming a Stronger acid) or unstable (forming a weak acid). I don't think there is a single rule that works all the time.
by MKearney_4G
Sun Dec 08, 2019 4:35 pm
Forum: Octet Exceptions
Topic: Reasoning for Octet Exception
Replies: 19
Views: 426

Re: Reasoning for Octet Exception

I know it's probably late but this video does a good job explaining it : https://youtu.be/96L6_IwyHRM
by MKearney_4G
Sun Dec 08, 2019 4:32 pm
Forum: Dipole Moments
Topic: Hydrogen bonding AND Dipole-Dipole?
Replies: 3
Views: 115

Hydrogen bonding AND Dipole-Dipole?

When we are writing out the IMFs between two molecules, isn't it redundant to list both Hydrogen bonding and D-D attraction if all of the dipoles are also forming H-bonds?
by MKearney_4G
Sat Dec 07, 2019 1:01 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Number of bonding sites on a chelating ligand
Replies: 1
Views: 56

Number of bonding sites on a chelating ligand

What are the rules for counting the number of sites that a polydentate ligand can bond to a cation?
by MKearney_4G
Sat Dec 07, 2019 12:56 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: how the bond works
Replies: 1
Views: 127

how the bond works

when you have a metal cation, like Platinum for example [Xe] 4f14 5d9 6s1 and you have the 2 Chlorines and 2 Ammines like in Cisplatin ( Cl [Ne] 3s² 3p⁵ and N [He] 2s2 2p3 ), which atom donates it's lone pair to the Coord. Covalent bond? How can you predict the number of bonding sites for a given ca...
by MKearney_4G
Sun Dec 01, 2019 11:42 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: Changes with temp?
Replies: 2
Views: 69

Changes with temp?

I heard from a friend that Kw changes with temperature, could somebody explain why? What is the trend? (higher temp higher KA? or the other way around)
by MKearney_4G
Sun Dec 01, 2019 11:35 pm
Forum: Air Pollution & Acid Rain
Topic: Clean Coal vs Dirty Coal?
Replies: 16
Views: 209

Re: Clean Coal vs Dirty Coal?

Coal is graded based on carbon-noncarbon content. Anthracite coal is considered "Clean" and has 92-98% Carbon content, whereas bituminous, sub-bituminous, and lignite coal have increasingly high impurity. Burning lower C-content coals (like lignite) would release a LOT of non-carbon into t...
by MKearney_4G
Sun Dec 01, 2019 11:27 pm
Forum: Lewis Acids & Bases
Topic: Difference between Lewis and Bronsted
Replies: 4
Views: 37

Re: Difference between Lewis and Bronsted

Lewis acids/bases are defined based on the sharing of electron pairs, while Bronsted-Lowry acids/bases are defined based on being a proton donor or acceptor.
by MKearney_4G
Sun Dec 01, 2019 11:23 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Determing Coordination Number
Replies: 5
Views: 52

Re: Determing Coordination Number

I believe that the coordination number refers to the number of bonds within a complex. The example in class was [Fe(CN)6]4- has a coordination number of 6, as there are 6 bonds. My understanding is that each atom has a "coordination number," which equals the number of bonds that the atom ...
by MKearney_4G
Sun Dec 01, 2019 11:18 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Stability
Replies: 1
Views: 33

Stability

Stability-wise how do ligands form? When would a metal atom sharing a pair of electrons be lower energy than just forming a normal amount of covalent bonds and be done?
by MKearney_4G
Sun Dec 01, 2019 7:14 pm
Forum: Identifying Acidic & Basic Salts
Topic: Neutralization
Replies: 3
Views: 280

Re: Neutralization

If a salt has a really weak conjugate base, then it will form a stronger acid, and the opposite is also true.
Fe3+ can take out HO- ions from the water and thus increase the [H+].
by MKearney_4G
Sun Dec 01, 2019 7:10 pm
Forum: Polyprotic Acids & Bases
Topic: polyprotic v. bronsted
Replies: 3
Views: 119

Re: polyprotic v. bronsted

Bronsted-Lowry acids are just one way of looking at acids (as an H+ donor).

A Lewis acid is a molecule that will accept an electron pair from a compound, and it is often also a BL acid because H+ can do just that.
by MKearney_4G
Sun Dec 01, 2019 7:05 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Calculating pH
Replies: 4
Views: 44

Re: Calculating pH

When it is a strong acid, it's pretty straight forward: just take -log([H+]). When it is a weak acid, then you need to do math to figure out how much H+ there will be, since it's not just the same as the original amount of acid. For weak acids you use basically the quadratic formula. If X = [H+] and...
by MKearney_4G
Sun Dec 01, 2019 6:59 pm
Forum: Amphoteric Compounds
Topic: Identifying Them?
Replies: 12
Views: 202

Re: Identifying Them?

You can identify an amphoteric compound by seeing if it would be able to both accept and donate hydrogen atoms. So in this case, would water be amphoteric? Yes. Water is a prime example of an amphoteric compound. There are other important ones as well, though. "In chemistry, an amphoteric comp...
by MKearney_4G
Sun Dec 01, 2019 6:53 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: What is kA value?
Replies: 5
Views: 91

Re: What is kA value?

k is calculated by [concentration of products multiplied together]/[concentration of reactants multiplied together] when the solution is at equilibrium. When the M of products is really high compared to the M of reactants, that means the reaction is carried out to near completion. For dissociation o...
by MKearney_4G
Sun Nov 17, 2019 6:06 pm
Forum: Hybridization
Topic: Test 2 Topics
Replies: 11
Views: 167

Re: Test 2 Topics

Isabel Day 1D wrote:- Distinguish sigma and pi bonds by their shapes, properties, and component orbitals

Can somebody explain this?
by MKearney_4G
Sun Nov 17, 2019 5:53 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Grading
Replies: 7
Views: 117

Re: Grading

What happens (according to upperclassmen) is that after the final is scored, the grading scale is adjusted so that the average grade in the class becomes a B or B- (depending on who you ask). Basically the "floor" for each grade is dropped by a set percentage, so you can only be helped and...
by MKearney_4G
Sun Nov 17, 2019 5:42 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Consequences of polarizability
Replies: 4
Views: 135

Consequences of polarizability

I understand that it is easier to distort anions and I understand that cations have more polarizing power and why.
What is the consequence of this, though? How do we apply these properties to bonding or IMFs?
by MKearney_4G
Sun Nov 17, 2019 5:37 pm
Forum: Electronegativity
Topic: Bond type for FeO2?
Replies: 3
Views: 173

Bond type for FeO2?

My TA last discussion said that FeO2 wasn't exactly an ionic bond, so I was wondering what type of bond it is?

The electronegativity difference is 1.6, and 1.5< 1.6 <2.
by MKearney_4G
Sun Nov 17, 2019 5:33 pm
Forum: Coordinate Covalent Bonds
Topic: bond question
Replies: 5
Views: 187

Re: bond question

In general I think pretty much all of the stuff we talk about in this class occurs in nature. You can think of bonds as attempts to lower the energy of the atom. If forming a coord. covalent bond brings the atom to a lower energy that it had with a lone pair, it will do it.
by MKearney_4G
Sun Nov 10, 2019 6:43 pm
Forum: Resonance Structures
Topic: Contribution of each structure?
Replies: 4
Views: 179

Contribution of each structure?

Some resonance structures are really unstable and some are more stable. Is there a way to indicate the contribution of each RS to the molecule?
by MKearney_4G
Sun Nov 10, 2019 6:40 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: High Distortion
Replies: 4
Views: 86

Re: High Distortion

So would you say that electrons farther from the nucleus (higher energy) are more easily distorted?
by MKearney_4G
Sun Nov 10, 2019 6:19 pm
Forum: Dipole Moments
Topic: Van der Waals
Replies: 2
Views: 32

Re: Van der Waals

There are two types of Van Der Waals forces, London dispersion forces (short term and weak) and Dipole-Dipole forces, which are longer term and stronger. They are BOTH reffered to as Van Der Waals forces. It is important to know when a molecule is going to have a dipole-dipole interaction and when i...
by MKearney_4G
Sun Nov 10, 2019 6:12 pm
Forum: Dipole Moments
Topic: Ionic vs Covalent Solubility
Replies: 3
Views: 36

Re: Ionic vs Covalent Solubility

Both can be soluble in water, what determines solubility is the polarity of the molecule, not the type of bond, though they are related. A molecule can have nonpolar bonds and polar bonds, like alcohols, and be fully miscible in water. Just remember "like dissolves like" and some solubilit...
by MKearney_4G
Sun Nov 10, 2019 6:03 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR Reference sheet for test?
Replies: 1
Views: 21

VSEPR Reference sheet for test?

Are we going to have a reference sheet with the names and bond angles for common VSEPR structures for the Test 2/ Final? Or do we have to memorize it
by MKearney_4G
Sun Nov 03, 2019 11:16 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: +- vs Uncertainty
Replies: 3
Views: 162

+- vs Uncertainty

In most calculations we get a number like "32+-0.25 meters". When we calculate uncertainty, do we use 0.25 as deltaX or 0.5?
by MKearney_4G
Sun Nov 03, 2019 11:13 pm
Forum: Lewis Structures
Topic: Showing work for valence electrons
Replies: 3
Views: 54

Re: Showing work for valence electrons

For each atom I don't think you need to show how you counted them, i.e. S subshell + P subshell,

But for the total number of Valance electrons in the molecule for Formal Charge you should show a quick addition of all the atoms. This will also help you not make mistakes.
by MKearney_4G
Sun Nov 03, 2019 9:43 pm
Forum: Dipole Moments
Topic: Why can water break up otherwise strong Ionic bonds?
Replies: 1
Views: 23

Why can water break up otherwise strong Ionic bonds?

Ionic bonds are incredibly strong normally, but why does water break some of them apart so easily? The hydrogen bond only has a small dipole-dipole attraction, why does this seem to so effectively annihilate ionic bonds like NaCl, for example?
by MKearney_4G
Sun Nov 03, 2019 9:20 pm
Forum: Lewis Structures
Topic: CH3CNO Resonance ???
Replies: 2
Views: 365

CH3CNO Resonance ???

The most stable molecule makes sense, as O-N---C-, but the resonance structures violate a lot of rules. For reference, O--N--C- is one and O---N-C- is the other. Why does this molecule have resonance structure where a carbon has a lone pair (instead of just staying in the first structure where all t...
by MKearney_4G
Sun Nov 03, 2019 9:08 pm
Forum: Resonance Structures
Topic: Reasonable resonance structures?
Replies: 1
Views: 48

Reasonable resonance structures?

In an example we did in class, one of our structures had all atoms with a FC=0 and the other resonance structure had two FC!=0, one was -1 and one was +1. Since having a FC of -1 / +1 is less stable, why is this resonance structure ever going to occur? And if it does occur, where does one draw the l...
by MKearney_4G
Sat Nov 02, 2019 10:57 pm
Forum: Octet Exceptions
Topic: Cl as an expanded octet
Replies: 3
Views: 59

Re: Cl as an expanded octet

AngieGarcia_4F wrote:I googled it and found the example: ClF3


To add to this, one of the problems on our practice exam was to draw ClO4-, and the only correct way to do it is to know that Cl can access the 3d subshell and accept more electrons. Always check the formal charge to make sure your molecule works out ;)
by MKearney_4G
Sat Nov 02, 2019 10:48 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Loss from 4s over 3d?
Replies: 4
Views: 52

Loss from 4s over 3d?

When an electron is added to an n=4 d block atom, it is added to the 4s subshell because it is most stable. Then the 3d block begins to be filled. When removing an e- from an atom with 3d electrons, though, you remove them from the 4s subshell first. Why does it remove these first if they are suppos...
by MKearney_4G
Tue Oct 29, 2019 11:31 pm
Forum: Resonance Structures
Topic: Faster way to write resonance structures?
Replies: 2
Views: 45

Faster way to write resonance structures?

I guess it's fine when there are only 3 different structures but sometimes there are more.
Is there a shorter notation for Lewis Dot Diagrams?
by MKearney_4G
Tue Oct 29, 2019 4:03 pm
Forum: Formal Charge and Oxidation Numbers
Topic: When would a compound not have FC=0?
Replies: 2
Views: 54

When would a compound not have FC=0?

Like the title says, what would the conditions have to be for a formal charge to be greater than or less than 0?
by MKearney_4G
Mon Oct 21, 2019 1:04 am
Forum: Photoelectric Effect
Topic: 0KE electron?
Replies: 2
Views: 52

0KE electron?

We learned that if you remove an electron using exactly the work function amount of energy that the electron will have 0KE. While mathematically this makes sense, how is the electron "removed" if it is not moving? If you give it the threshold energy then it will escape the atom, but then w...
by MKearney_4G
Mon Oct 21, 2019 1:04 am
Forum: Photoelectric Effect
Topic: 0KE electron?
Replies: 2
Views: 74

0KE electron?

We learned that if you remove an electron using exactly the work function amount of energy that the electron will have 0KE. While mathematically this makes sense, how is the electron "removed" if it is not moving? If you give it the threshold energy then it will escape the atom, but then w...
by MKearney_4G
Mon Oct 21, 2019 1:01 am
Forum: Quantum Numbers and The H-Atom
Topic: Spin and orbitals
Replies: 4
Views: 49

Spin and orbitals

In electron configurations, why do we fill up all the orbital slots with electrons of the same spin? Why can't we do up-down-up-down? Is it just convention or is there a scientific reason that we fill them all up with the same spin FIRST and the other spin LAST
by MKearney_4G
Mon Oct 21, 2019 12:57 am
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Minimum uncertainty?
Replies: 2
Views: 51

Minimum uncertainty?

If the HBI Equation gives us the minimum uncertainty, what does this mean in context? Does this imply that the object could actually have a greater uncertainty in its position/momentum?
by MKearney_4G
Mon Oct 21, 2019 12:55 am
Forum: Trends in The Periodic Table
Topic: Difference between electron affinity and electronegativity?
Replies: 3
Views: 36

Difference between electron affinity and electronegativity?

Like the title says, can somebody explain the difference between electron affinity and electronegativity?
by MKearney_4G
Sun Oct 20, 2019 2:33 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Why is copper like this?
Replies: 6
Views: 81

Why is copper like this?

[Ar] 3d10 4s1 is the Electron Config for Cu,
but if you do it systematically you get 4s2 3d9.
I get that the 4s electron is more "stable" in the 3d suborbital, but why? And why does this not happen for any other element in the row?

Same with chromium . . .
by MKearney_4G
Mon Oct 14, 2019 6:08 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: *Lowest possible energy?
Replies: 2
Views: 51

*Lowest possible energy?

How would one calculate the lowest possible energy of a particle?
by MKearney_4G
Mon Oct 14, 2019 5:56 pm
Forum: Properties of Light
Topic: Variables and Constants for this Unit
Replies: 2
Views: 33

Variables and Constants for this Unit

Variables: E - Energy (J) λ - wavelength (m) v - frequency (Hertz, Hz, 1/s or s^-1) n - electron shell (whole numbers w/out units) ---------------------------------- Constants: R - Rydberg's Constant (1.09678*10^7 m^-1) c = Speed of Light in vacuum (3*10^8 m/s) h - Planck's Constant (6.626176 x 10-3...
by MKearney_4G
Mon Oct 14, 2019 5:35 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Shells, Subshells, Orbitals
Replies: 4
Views: 1418

Re: Shells, Subshells, Orbitals

So is the 1s orbital completely seperate from the 2s orbital then?
by MKearney_4G
Mon Oct 14, 2019 5:28 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Positive and Negative signs?
Replies: 5
Views: 75

Positive and Negative signs?

I am unclear as to why sometimes we say that the energy is negative and sometimes it is positive. Could somebody explain what the signs mean in the context of Energy?
by MKearney_4G
Mon Oct 14, 2019 5:23 pm
Forum: *Shrodinger Equation
Topic: Hamiltonian
Replies: 5
Views: 85

Re: Hamiltonian

My understanding was that a Hamiltonian was a "second derivative function", but more importantly that it is an operation you do on the wave function to give the total energy. Hψ gives the total energy (Kinetic+Potential) of the system. Hψ=Eψ.
by MKearney_4G
Sun Oct 06, 2019 5:47 pm
Forum: Empirical & Molecular Formulas
Topic: Compound Names, HW problem G17
Replies: 2
Views: 82

Re: Compound Names, HW problem G17

When there is a dot followed by water molecules, it means that the element is a "hydrate." The number by H2O is the ratio of whatever:water that you are dealing with. You typically include the water in calculations as far as I know.
by MKearney_4G
Sun Oct 06, 2019 5:43 pm
Forum: Balancing Chemical Reactions
Topic: HW problem H11
Replies: 4
Views: 82

Re: HW problem H11

"In a second stage, the Fe3O4 reacts further with carbon monoxide to produce solid elemental iron and carbon dioxide. Write the balanced equation for each stage in the process." Fe3O4 + CO = Fe + CO2 has the correct elements, so you are correct in that aspect. To balance it, first balance ...
by MKearney_4G
Sun Oct 06, 2019 5:35 pm
Forum: Limiting Reactant Calculations
Topic: Homework M. 15
Replies: 3
Views: 87

Homework M. 15

"Aluminum metal reacts with chlorine gas to produce aluminum chloride. In one preparation, 255 g of aluminum is placed in a container holding 535 g of chlorine gas. After reaction ceases, it is found that 300. g of aluminum chloride has been produced. (a) Write the balanced equation for the rea...
by MKearney_4G
Sun Oct 06, 2019 5:22 pm
Forum: Significant Figures
Topic: Periodic table AMU values
Replies: 2
Views: 39

Periodic table AMU values

Is it acceptable to choose to use a periodic table that gives AMU in fewer SigFigs than the initial parameters given in the problem? ex. Problem says 1.0003 mL (5SF) of H2SO4 and you use 98.08 (4SF) as your MM, then your final answer will have fewer SigFigs than the actual problem set you up for. Fo...
by MKearney_4G
Sun Oct 06, 2019 5:14 pm
Forum: Balancing Chemical Reactions
Topic: Alternative to Guess and Check?
Replies: 5
Views: 74

Alternative to Guess and Check?

In my discussion section we had a balancing problem: S + HNO3 <=> H2SO4 + NO2 + H2O While I now understand how to do this particular problem (1,6,1,6,2), it took me a LONG time I am not confident I could do this on a test. Is there an alternative, more procedural/mathematical way to balance chemical...

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