Search found 26 matches

by Hannah Lee 1B
Tue Jun 05, 2018 2:58 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Trigonal Planar vs Trigonal Pyramidal
Replies: 5
Views: 2707

Re: Trigonal Planar vs Trigonal Pyramidal

trigonal planar has 3 bonding regions and no lone pairs, with sp2 hybridization, while trigonal pyramidal has 3 bonding regions, 1 lone pair and sp3 hybridization. also in 3D trigonal planar would be like a flat triangle while trigonal pyramidal is pyramid-shaped
by Hannah Lee 1B
Tue Jun 05, 2018 2:52 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Problem 17.29
Replies: 3
Views: 125

Re: Problem 17.29

my TA said we don't need to know that, however I think you're more or less correct and also using the charges of the other atoms/ions in the molecule can be used to find the ligand's charge.
by Hannah Lee 1B
Tue Jun 05, 2018 2:50 pm
Forum: Lewis Acids & Bases
Topic: Strength between 2 weak/strong acids/bases
Replies: 5
Views: 292

Re: Strength between 2 weak/strong acids/bases

^yes, the more easily an acid/base dissociates the stronger it is. However, I don't think you'd actually know for sure unless you compared the acid/base dissociation constants, which we haven't used this quarter.
by Hannah Lee 1B
Tue Jun 05, 2018 2:35 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Hybridization
Replies: 7
Views: 261

Re: Hybridization

The hybridization correlates with the number of electron pair regions around the central atom, so linear (2) would be sp, trigonal planar (3) is sp2 (add another p), tetrahedral (4) is sp3, then move on to d, etc etc.
by Hannah Lee 1B
Tue Jun 05, 2018 2:33 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Ligands
Replies: 3
Views: 122

Re: Ligands

a ligand is an ion/molecule that binds to a central metal atom, usually through donation of at least one of the ligand's electron pairs.
by Hannah Lee 1B
Tue May 29, 2018 4:37 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond angles and lone pairs
Replies: 4
Views: 193

Re: Bond angles and lone pairs

If the bond angle is smaller than usual, then there are more lone pairs. For example, a bent shape with AX2E2 (H2O) has a bond angle of <109.5 while a bent shape with AX2E (O3) has a bond angle of <120.
by Hannah Lee 1B
Fri May 25, 2018 2:43 pm
Forum: Lewis Acids & Bases
Topic: Lewis acid vs. base
Replies: 5
Views: 193

Re: Lewis acid vs. base

Since lewis acids are electron acceptors and bases are electron donors, when you draw the molecule an acid would have space to accept electrons (for example, BF3 can accept a pair to form a full octet) and a base would have extra lone pairs (ex. NH3)
by Hannah Lee 1B
Mon May 21, 2018 12:10 am
Forum: Bond Lengths & Energies
Topic: 3.87
Replies: 5
Views: 231

Re: 3.87

The strongest bonds are in CF4, then CCl4, then CBr4. This is because F has the smallest atomic radius, which results in a shorter bond length and a stronger bond.
by Hannah Lee 1B
Mon May 21, 2018 12:05 am
Forum: Dipole Moments
Topic: Difference between Dipole-Dipole and Dipole-Induced dipole?
Replies: 2
Views: 97

Re: Difference between Dipole-Dipole and Dipole-Induced dipole?

H-F already has dipoles, so in H-F H-F the negative dipole of F interacts with the positive H on the other molecule in a dipole-dipole interaction. In H-Cl N-N, N-N is neutral (has no dipoles) while H-Cl is positive at H and negative at Cl. The dipoles in H-Cl attract/repel electrons in N-N and caus...
by Hannah Lee 1B
Mon May 21, 2018 12:00 am
Forum: Electronegativity
Topic: Electronegativiry vs electron affinity [ENDORSED]
Replies: 4
Views: 285

Re: Electronegativiry vs electron affinity [ENDORSED]

The trends are the same - they both increase upward and to the right. Electronegativity is the ability for a bonded atom to attract bonding electrons to itself while electron affinity is a measurable value (the energy change when an atom gains an electron).
by Hannah Lee 1B
Sun May 20, 2018 5:11 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polarization
Replies: 2
Views: 195

Re: Polarization

The anion holds its electrons less tightly than the cation does, due to greater shielding/repulsion caused by the additional electrons - as a result, its cloud is more susceptible to distortion
by Hannah Lee 1B
Sun May 13, 2018 11:34 pm
Forum: Formal Charge and Oxidation Numbers
Topic: How do I determine Formal Charge?
Replies: 2
Views: 136

Re: How do I determine Formal Charge?

Yes, ideally you would try to draw the molecule in such a way that the formal charge of each atom is 0. However, in cases like an odd number of electrons (ex. NO), incomplete octets (ex. BF3), or expanded valence shells (atoms with 3d and up), the octet rule can be broken and the formal charges can ...
by Hannah Lee 1B
Sun May 13, 2018 11:08 pm
Forum: Ionic & Covalent Bonds
Topic: Covalent Bonds
Replies: 4
Views: 166

Re: Covalent Bonds

The central atom has to bond with more atoms around it - a central atom with lower ionization energy would more readily share its electrons (since it's not "holding onto" its electrons as tightly). Also, atoms with higher ionization energy usually have more lone pairs, which would cause mo...
by Hannah Lee 1B
Mon May 07, 2018 3:19 am
Forum: Trends in The Periodic Table
Topic: Difference between Periodic trends [ENDORSED]
Replies: 4
Views: 268

Re: Difference between Periodic trends [ENDORSED]

Electron affinity is a measure of energy change when an electron is added while electronegativity is how attracted an atom is to electrons. While electron affinity is increasing, electronegativity is decreasing since as an atom is less attractive to electrons, it requires more energy to add an elect...
by Hannah Lee 1B
Mon May 07, 2018 3:15 am
Forum: Trends in The Periodic Table
Topic: 2.67 part c) and d) [ENDORSED]
Replies: 5
Views: 223

Re: 2.67 part c) and d) [ENDORSED]

Chlorine and lithium have higher electron affinity than bromine and sodium because as you go up a group, there is less shielding and you're closer to the nucleus, making it easier to add electrons. When an electron is added to a neutral atom, energy is released, and the harder it is to add electrons...
by Hannah Lee 1B
Mon May 07, 2018 2:52 am
Forum: Trends in The Periodic Table
Topic: Across vs Down Trend
Replies: 2
Views: 125

Re: Across vs Down Trend

Across a period the radius gets smaller while down a group it gets bigger. Since silver is lower and to the left, it is bigger than zinc in both aspects. Comparing elements like nitrogen and sulfur would be more ambiguous, however it's not likely that questions like that would be asked.
by Hannah Lee 1B
Mon May 07, 2018 2:45 am
Forum: Ionic & Covalent Bonds
Topic: Help on 3.9 (b) [ENDORSED]
Replies: 2
Views: 81

Re: Help on 3.9 (b) [ENDORSED]

M2+ means that the atom has lost two electrons. That means without the 2+ charge it would be [Ar]3d^(6)4s^(2), which is Fe, so M is Fe
by Hannah Lee 1B
Mon Apr 30, 2018 3:35 pm
Forum: Quantum Numbers and The H-Atom
Topic: Nodal Planes- what are they exactly? [ENDORSED]
Replies: 6
Views: 5027

Re: Nodal Planes- what are they exactly? [ENDORSED]

Nodal planes are where you won't find any electrons.

Radial nodal planes are spheres that occur as N increases (between s shells, # angular planes = N-L-1)
Angular nodal planes are flat and occur within orbitals (# angular planes = L)
by Hannah Lee 1B
Mon Apr 30, 2018 3:16 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Nodes
Replies: 2
Views: 70

Re: Nodes

Nodes are where there aren't any electrons - radial nodes are spherical, between each electron shell. Angular nodes are flat planes within orbitals. There are n-L-1 radial nodes and L angular nodes For example 3s: has 2 radial nodes and no angular nodes. 2p: has 0 radial nodea and 1 angular node (3 ...
by Hannah Lee 1B
Mon Apr 30, 2018 3:10 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: HOMEWORK PROBLEM 2.19
Replies: 3
Views: 140

Re: HOMEWORK PROBLEM 2.19

n is the principal quantum number (energy level/shell) while L describes the subshell (s, p, d, f). For part a: Values for L (subshells) ranges from 0 - (n-1), so when n=7, L could be anything from 0-7. Thus, 8 values are possible. You can work backward as well. For parts b and c: ml describes the d...
by Hannah Lee 1B
Mon Apr 23, 2018 3:14 pm
Forum: DeBroglie Equation
Topic: de broglie [ENDORSED]
Replies: 1
Views: 88

de broglie [ENDORSED]

In my notes, I have written:
Energy, E= p*v
For a photon: E = p*c and E = hv = hc/λ

How can E equal both p*v and p*c? Or did I write it down wrong
by Hannah Lee 1B
Mon Apr 23, 2018 3:08 pm
Forum: Properties of Electrons
Topic: Example from Lecture #8 [ENDORSED]
Replies: 2
Views: 214

Re: Example from Lecture #8 [ENDORSED]

https://s3-us-west-2.amazonaws.com/cour ... 06_00a.jpg

^
The picture linked above explains! the wave on the left is allowed b/c it overlaps with itself perfectly while the one on the right isn't b/c the wave is broken
by Hannah Lee 1B
Mon Apr 23, 2018 3:02 pm
Forum: Einstein Equation
Topic: finding frequency from Einstein's equation [ENDORSED]
Replies: 3
Views: 190

Re: finding frequency from Einstein's equation [ENDORSED]

plug in momentum to λ = h/p to find λ , then plug that into λ =hv to find v
by Hannah Lee 1B
Sat Apr 14, 2018 5:31 pm
Forum: Balancing Chemical Reactions
Topic: Whole numbers
Replies: 7
Views: 326

Re: Whole numbers

subscripts are always whole numbers. the coefficients can be fractions while you're balancing to make it easier, but at the end you'd have to multiply everything by a common denominator to get whole numbers
by Hannah Lee 1B
Sat Apr 14, 2018 5:30 pm
Forum: Molarity, Solutions, Dilutions
Topic: dilution
Replies: 4
Views: 240

dilution

when you mix one solution of a certain molarity and volume with another solution of a different molarity and volume, how do you find the new molarity? is it just adding everything
by Hannah Lee 1B
Sat Apr 14, 2018 5:22 pm
Forum: Limiting Reactant Calculations
Topic: Two limiting reactants?
Replies: 10
Views: 780

Re: Two limiting reactants?

No, they will either both be completely used up or only one will be in shortage

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