Search found 32 matches
- Sat Dec 08, 2018 2:07 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Energy Levels
- Replies: 2
- Views: 667
Re: Energy Levels
It gains energy, so delta E will be positive
- Sat Dec 08, 2018 2:06 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: how can a hydrogen bond form
- Replies: 2
- Views: 402
Re: how can a hydrogen bond form
yes, they must bond to hydrogen in order to form a hydrogen bond.
Re: Cyanide
The textbook is updated to the new "cyanido" naming, but "cyano" is used in lecture. Either is correct!
- Wed Dec 05, 2018 11:19 am
- Forum: Sigma & Pi Bonds
- Topic: Identifying sigma & pi bonds
- Replies: 4
- Views: 874
Re: Identifying sigma & pi bonds
Yes- sigma bonds are always single bonds. So, in a double bond there will be 1 sigma bond and 1 pi bond, and in a triple bond there will be 1 sigma bond and 2 pi bonds. I don't believe we will have to draw this, but basically in a sigma bond the orbitals overlap end-to-end and in a pi bond they over...
- Sat Dec 01, 2018 5:07 pm
- Forum: Naming
- Topic: Naming/ oxidation numbers/ charges
- Replies: 2
- Views: 256
Re: Naming/ oxidation numbers/ charges
The overall charge of the compound will be given outside of the bracket. From there, add the charges you already know within the compound (ex: OH has a -1 charge) and subtract from the total charge, which will leave you with the oxidation state of the transition metal.
- Sat Dec 01, 2018 5:04 pm
- Forum: Naming
- Topic: How to name
- Replies: 6
- Views: 584
Re: How to name
Ligands should always be ordered alphabetically.
- Sat Dec 01, 2018 3:33 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Practice Questions for Final
- Replies: 3
- Views: 573
Re: Practice Questions for Final
I believe Karen posted a bunch of review questions, she has a lot of helpful worksheets for peer learning sessions. You should be able to find them if you search 'Karen' in the search bar!
- Fri Nov 30, 2018 4:25 pm
- Forum: Electronegativity
- Topic: Exceptions
- Replies: 7
- Views: 1046
Re: Exceptions
The exception for ionization energy is that Nitrogen has a greater ionization energy than Oxygen, even though the trend follows that the energy increases across a period. The other exception is for electron affinity. Carbon has a greater electron affinity than Nitrogen which does not follow the tren...
- Wed Nov 21, 2018 2:04 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Drawing out Molecular Shape
- Replies: 3
- Views: 333
Re: Drawing out Molecular Shape
I believe we won't be required to actually draw the models, as mentioned in lecture. You will need to know the structure name and formula (AXE) though.
- Wed Nov 21, 2018 1:59 pm
- Forum: Sigma & Pi Bonds
- Topic: formation of pi bond
- Replies: 6
- Views: 611
Re: formation of pi bond
No, pi bonds are formed when there's a double or triple bond. So in a double bond, one bond will be a sigma bond and the other will be a pi bond. In a triple bond, one bond will be a sigma bond and 2 would be pi bonds.
- Wed Nov 21, 2018 1:57 pm
- Forum: Lewis Structures
- Topic: Complete Lewis Structures
- Replies: 4
- Views: 445
Re: Complete Lewis Structures
I think either is fine, but I've noticed the separate structure seems more common for ionic compounds like salts.
- Thu Nov 15, 2018 4:04 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: bond angles with lone electrons
- Replies: 2
- Views: 307
Re: bond angles with lone electrons
I don't believe we will need to know the exact angles in structures with lone pairs, but just need to acknowledge that those angles are smaller than they would be without the presence of the lone pairs.
- Thu Nov 15, 2018 10:47 am
- Forum: Lewis Structures
- Topic: 7th Edition #2E.13
- Replies: 3
- Views: 2843
Re: 7th Edition #2E.13
As mentioned above, the goal is to minimize formal charge. In ions with negative charges, however, usually oxygen should "carry" the negative charge rather than the central atom, which explains why using a single bond would be more stable.
- Thu Nov 15, 2018 10:44 am
- Forum: Lewis Structures
- Topic: Lewis Structure of H2C(NH2)COOH
- Replies: 1
- Views: 661
Re: Lewis Structure of H2C(NH2)COOH
In large organic compounds like this, the structure typically follows the same order as how the formula is written. So, you will have 2 H attached to 1 C, etc. The parenthesis signify that those elements are all bonded together. So, the N will have 2 H bonded to it and then will bond to the C that h...
- Fri Nov 09, 2018 2:52 pm
- Forum: Bond Lengths & Energies
- Topic: bond angles
- Replies: 3
- Views: 410
bond angles
Will the bond angles for a specific molecular shape always be the same for that shape regardless of what elements make it up? For example, BF3 has a trigonal planar shape and bond angles of 120 degrees each. Will another molecule with this trigonal planar shape also have bond angles of 120 degrees?
- Fri Nov 09, 2018 2:47 pm
- Forum: Dipole Moments
- Topic: Boiling Points
- Replies: 3
- Views: 346
Re: Boiling Points
Sulfur is not as electronegative as oxygen. Because of this, H2S is not as polar as water and has weaker intermolecular forces and therefore a lower boiling point.
- Fri Nov 09, 2018 2:41 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Polarizability v. Electronegativity
- Replies: 3
- Views: 2259
Re: Polarizability v. Electronegativity
Electronegativity describes an element's ability to pull electrons closer towards its nucleus, which explains why electronegativity increases across a period (elements "want" electrons more to reach octet) and decreases down a group (atomic radius is larger so shielding causes a looser gri...
- Sat Nov 03, 2018 12:22 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Node
- Replies: 2
- Views: 349
Re: Node
A node shows the region where there is 0 electron density, so therefore 0 probability of finding electrons there, as mentioned in the comment above. If you're asked how many nodes are in a configuration, # nodes = (n-1). So, in an s orbital that would be 0 nodes (spherical shape), in a p orbital (n=...
- Sat Nov 03, 2018 12:09 pm
- Forum: Trends in The Periodic Table
- Topic: Metals, metalloids, and nonmetals
- Replies: 3
- Views: 490
Re: Metals, metalloids, and nonmetals
Basically, the elements in the s, d, and f blocks (except H & He) are metals. As you get towards the right side of the table, the elements are mostly nonmetals. Between the metals and non-metals, there is a diagonal pattern of metalloids (B, Si, Ge, As, Sb, Te, Po). It's easier to see with a pho...
- Sat Nov 03, 2018 12:01 pm
- Forum: Properties of Light
- Topic: Photoelectric Effect - waves vs. photons
- Replies: 3
- Views: 611
Re: Photoelectric Effect - waves vs. photons
The photoelectric effect describes light as having particle-like properties. Because of this, increasing intensity of long-wavelength light will not cause electrons to be ejected because each individual photon is interacting with individual electrons in the metal, so if the individual photons don't ...
- Sat Oct 27, 2018 5:03 pm
- Forum: Ionic & Covalent Bonds
- Topic: Replacement for Modules
- Replies: 7
- Views: 637
Re: Replacement for Modules
There's a website called "learnbacon" that has chemistry and biology notes on it that are very helpful!
- Sat Oct 27, 2018 5:02 pm
- Forum: Lewis Structures
- Topic: Lewis Dot Structures
- Replies: 3
- Views: 422
Lewis Dot Structures
As shown in class, certain compounds like C2 can be represented with a combination of single, double, or triple bonds. Does it matter which way we represent it as long as we show the correct total number of electrons?
- Sat Oct 27, 2018 4:53 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Homework Question 1D.23
- Replies: 2
- Views: 254
Re: Homework Question 1D.23
Given that l=1, that corresponds to the p-subshell, so there are 3 possible orbitals. I don't believe the fact that it is the 2p orbital will affect the amount of orbitals that could possibly be filled.
- Sat Oct 20, 2018 1:50 pm
- Forum: Properties of Light
- Topic: Calculating the wavelength of light
- Replies: 7
- Views: 1140
Re: Calculating the wavelength of light
The 2.998x10^8 value is technically more precise, however Professor Lavelle told us that it's ok to use 3x10^8 as the value for speed of light during lecture!
- Sat Oct 20, 2018 1:48 pm
- Forum: Photoelectric Effect
- Topic: Homework Question 1A.7
- Replies: 2
- Views: 286
Re: Homework Question 1A.7
Use the equation (wavelength)= (speed of light)/(frequency), so the wavelength = (3x10^8)/(2.0x10^18), which should give you 150 pm
- Tue Oct 16, 2018 5:12 pm
- Forum: Trends in The Periodic Table
- Topic: Homework
- Replies: 10
- Views: 694
Homework
Are we expected to include questions from each section of the unit (in this case, sections 1A-1F) on the homework even if the topics haven't yet been covered in lecture?
- Sat Oct 13, 2018 3:47 pm
- Forum: Properties of Light
- Topic: Measurable wavelengths
- Replies: 5
- Views: 470
Re: Measurable wavelengths
The minimum measurable wavelength is 10^-18 nm.
- Sat Oct 13, 2018 3:45 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: Changing Units
- Replies: 10
- Views: 789
Re: Changing Units
In terms of the problem-solving process, I would always use standard SI units (L) to make sure your calculations are correct. You can leave your answers in standard SI units, but you could also convert them to match the given units in the problem, as long as the answer is correct!
- Sat Oct 13, 2018 3:42 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Wavelike properties
- Replies: 7
- Views: 395
Re: Wavelike properties
All objects do exhibit some sort of wavelike properties. However, as mentioned in lecture, the objects that have wavelengths smaller than 10^-18 nm (ex: 10^-34) will not be considered to express detectable wavelike behavior.
- Fri Oct 05, 2018 3:50 pm
- Forum: Significant Figures
- Topic: Number of Sig Fig
- Replies: 8
- Views: 577
Re: Number of Sig Fig
Given that you will be answering part a with a rounded answer for sig figs, I think it's fine to use that rounded answer in part b because your final answer for part b will ultimately be rounded for sig figs as well.
- Fri Oct 05, 2018 3:45 pm
- Forum: Balancing Chemical Reactions
- Topic: Balancing reactions tips
- Replies: 29
- Views: 2044
Re: Balancing reactions tips
I find it much easier to make sure my work is correct when I can have clear visuals to make sure everything is balanced. I usually keep a running tally while I'm balancing my equation for each individual element, which makes the process much easier to keep track of for more complex equations.
- Fri Oct 05, 2018 3:34 pm
- Forum: Significant Figures
- Topic: All students read this sig fig post [ENDORSED]
- Replies: 170
- Views: 33545
Re: All students read this sig fig post [ENDORSED]
angelagd3l wrote:When we are rounding, how can we determine how many sig figs we need to keep in the problem?
The final answer should have the same number of sig figs as the value given in the problem itself with the LEAST amount of sig figs.