Search found 32 matches

by annaspain
Sat Dec 08, 2018 2:07 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Energy Levels
Replies: 2
Views: 139

Re: Energy Levels

It gains energy, so delta E will be positive
by annaspain
Wed Dec 05, 2018 11:20 am
Forum: Naming
Topic: Cyanide
Replies: 6
Views: 91

Re: Cyanide

The textbook is updated to the new "cyanido" naming, but "cyano" is used in lecture. Either is correct!
by annaspain
Wed Dec 05, 2018 11:19 am
Forum: Sigma & Pi Bonds
Topic: Identifying sigma & pi bonds
Replies: 4
Views: 188

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...
by annaspain
Sat Dec 01, 2018 5:07 pm
Forum: Naming
Topic: Naming/ oxidation numbers/ charges
Replies: 2
Views: 53

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.
by annaspain
Sat Dec 01, 2018 5:04 pm
Forum: Naming
Topic: How to name
Replies: 6
Views: 154

Re: How to name

Ligands should always be ordered alphabetically.
by annaspain
Sat Dec 01, 2018 3:33 pm
Forum: Administrative Questions and Class Announcements
Topic: Practice Questions for Final
Replies: 3
Views: 145

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!
by annaspain
Fri Nov 30, 2018 4:25 pm
Forum: Electronegativity
Topic: Exceptions
Replies: 4
Views: 151

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...
by annaspain
Wed Nov 21, 2018 2:04 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Drawing out Molecular Shape
Replies: 3
Views: 78

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.
by annaspain
Wed Nov 21, 2018 1:59 pm
Forum: Sigma & Pi Bonds
Topic: formation of pi bond
Replies: 6
Views: 147

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.
by annaspain
Wed Nov 21, 2018 1:57 pm
Forum: Lewis Structures
Topic: Complete Lewis Structures
Replies: 4
Views: 96

Re: Complete Lewis Structures

I think either is fine, but I've noticed the separate structure seems more common for ionic compounds like salts.
by annaspain
Thu Nov 15, 2018 4:04 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: bond angles with lone electrons
Replies: 2
Views: 65

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.
by annaspain
Thu Nov 15, 2018 10:47 am
Forum: Lewis Structures
Topic: 7th Edition #2E.13
Replies: 3
Views: 112

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.
by annaspain
Thu Nov 15, 2018 10:44 am
Forum: Lewis Structures
Topic: Lewis Structure of H2C(NH2)COOH
Replies: 1
Views: 73

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...
by annaspain
Fri Nov 09, 2018 2:52 pm
Forum: Bond Lengths & Energies
Topic: bond angles
Replies: 3
Views: 68

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?
by annaspain
Fri Nov 09, 2018 2:47 pm
Forum: Dipole Moments
Topic: Boiling Points
Replies: 3
Views: 86

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.
by annaspain
Fri Nov 09, 2018 2:41 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polarizability v. Electronegativity
Replies: 3
Views: 115

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...
by annaspain
Sat Nov 03, 2018 12:22 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Node
Replies: 2
Views: 111

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=...
by annaspain
Sat Nov 03, 2018 12:09 pm
Forum: Trends in The Periodic Table
Topic: Metals, metalloids, and nonmetals
Replies: 3
Views: 81

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...
by annaspain
Sat Nov 03, 2018 12:01 pm
Forum: Properties of Light
Topic: Photoelectric Effect - waves vs. photons
Replies: 3
Views: 135

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 ...
by annaspain
Sat Oct 27, 2018 5:03 pm
Forum: Ionic & Covalent Bonds
Topic: Replacement for Modules
Replies: 7
Views: 189

Re: Replacement for Modules

There's a website called "learnbacon" that has chemistry and biology notes on it that are very helpful!
by annaspain
Sat Oct 27, 2018 5:02 pm
Forum: Lewis Structures
Topic: Lewis Dot Structures
Replies: 3
Views: 78

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?
by annaspain
Sat Oct 27, 2018 4:53 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Homework Question 1D.23
Replies: 2
Views: 69

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.
by annaspain
Sat Oct 20, 2018 1:50 pm
Forum: Properties of Light
Topic: Calculating the wavelength of light
Replies: 7
Views: 129

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!
by annaspain
Sat Oct 20, 2018 1:48 pm
Forum: Photoelectric Effect
Topic: Homework Question 1A.7
Replies: 2
Views: 82

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
by annaspain
Tue Oct 16, 2018 5:12 pm
Forum: Trends in The Periodic Table
Topic: Homework
Replies: 10
Views: 172

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?
by annaspain
Sat Oct 13, 2018 3:47 pm
Forum: Properties of Light
Topic: Measurable wavelengths
Replies: 5
Views: 64

Re: Measurable wavelengths

The minimum measurable wavelength is 10^-18 nm.
by annaspain
Sat Oct 13, 2018 3:45 pm
Forum: Molarity, Solutions, Dilutions
Topic: Changing Units
Replies: 10
Views: 321

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!
by annaspain
Sat Oct 13, 2018 3:42 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Wavelike properties
Replies: 7
Views: 75

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.
by annaspain
Fri Oct 05, 2018 3:50 pm
Forum: Significant Figures
Topic: Number of Sig Fig
Replies: 8
Views: 131

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.
by annaspain
Fri Oct 05, 2018 3:45 pm
Forum: Balancing Chemical Reactions
Topic: Balancing reactions tips
Replies: 29
Views: 759

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.
by annaspain
Fri Oct 05, 2018 3:34 pm
Forum: Significant Figures
Topic: All students read this sig fig post [ENDORSED]
Replies: 91
Views: 8926

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.

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