Search found 31 matches

by Catherine Kim 3K
Tue Dec 04, 2018 12:59 pm
Forum: Lewis Acids & Bases
Topic: KBr
Replies: 5
Views: 119

Re: KBr

Br is below F on the periodic table, so it is bigger.
by Catherine Kim 3K
Tue Dec 04, 2018 12:57 pm
Forum: Naming
Topic: Coming up with formula from name
Replies: 3
Views: 63

Re: Coming up with formula from name

The formula [symbols] should be alphabetical and you put metal at the beginning. The neutral molecule should be at the end. You need the brackets to show the charge.
by Catherine Kim 3K
Tue Dec 04, 2018 12:48 pm
Forum: Amphoteric Compounds
Topic: amphoteric substances
Replies: 3
Views: 101

Re: amphoteric substances

Amphoteric substance is a molecule/ion that can act either as an acid or base. They should have transferable H and atom with lone pair electrons.
by Catherine Kim 3K
Tue Nov 27, 2018 1:26 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Central atom
Replies: 5
Views: 133

Re: Central atom

Generally the atom with the lowest ionization energy is the central atom.
by Catherine Kim 3K
Tue Nov 27, 2018 1:25 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: polarity vs. nonpolarity
Replies: 8
Views: 162

Re: polarity vs. nonpolarity

You should first draw a Lewis structure. Then, there are multiple methods to see if the structure is polar or nonpolar. You should check the polarity of bonds, the electron groups around the central atom, and symmetry of the molecule.
by Catherine Kim 3K
Tue Nov 20, 2018 1:03 pm
Forum: Sigma & Pi Bonds
Topic: sigma and pi bonds
Replies: 5
Views: 130

Re: sigma and pi bonds

Sigma bond is formed by end-to-end overlap of atomic orbitals while pi bond is formed by side to side overlap of atomic orbitals. Also sigma bonds tend to be stronger than pi bonds.
by Catherine Kim 3K
Tue Nov 20, 2018 12:58 pm
Forum: Bond Lengths & Energies
Topic: double bonds vs. single bonds
Replies: 5
Views: 133

Re: double bonds vs. single bonds

Double bonds are stronger than single bonds because double bonds add stability to compounds and restrict rotation around the bond axis. Double bonds have sigma bonds and pi bonds; double bonds are also shorter than single bonds because the extra bonding electrons pull atoms closer together.
by Catherine Kim 3K
Tue Nov 20, 2018 12:46 pm
Forum: Lewis Structures
Topic: Electronegativity
Replies: 4
Views: 128

Re: Electronegativity

The element with the smallest electronegativity is the central atom.
by Catherine Kim 3K
Thu Nov 15, 2018 12:53 pm
Forum: Dipole Moments
Topic: Van der Waals
Replies: 4
Views: 115

Re: Van der Waals

Yes. Van der Waals forces is a general term used to describe the intermolecular forces between molecules. There are two types of Van der Waals forces - London dispersion forces and dipole-dipole forces.
by Catherine Kim 3K
Thu Nov 15, 2018 12:47 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: polarizing power
Replies: 2
Views: 95

Re: polarizing power

Polarizing power does not only apply to cations. Anions also have polarizing power; larger anions will have greater polarizing power.
by Catherine Kim 3K
Thu Nov 15, 2018 12:42 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: polar vs nonpolar
Replies: 6
Views: 188

Re: polar vs nonpolar

The electronegativity of the atoms will be different in a polar bond. Yet, the electronegativity of the atoms will be equal in a nonpolar bond.
by Catherine Kim 3K
Wed Nov 07, 2018 5:36 pm
Forum: Lewis Structures
Topic: Formal charge question
Replies: 9
Views: 217

Re: Formal charge question

To see if your Lewis Diagram is the most likely arrangement is to first make sure you follow all the steps. 1. Count total number of valence electrons on molecule. 2. Draw single bonds between atoms. 3. Count how many electrons remain and assign them as lone pairs to fill valence shell. 4. If there ...
by Catherine Kim 3K
Wed Nov 07, 2018 5:31 pm
Forum: Lewis Structures
Topic: Central Atom
Replies: 3
Views: 94

Re: Central Atom

I use the least ionization energy to determine the central atom. Also, you could also look look for other clues to determine central atom: H is always at the ends, O is usually the one that has double bonds with another element, etc.
by Catherine Kim 3K
Wed Nov 07, 2018 5:24 pm
Forum: Bond Lengths & Energies
Topic: Calculating Bond Lengths
Replies: 4
Views: 115

Re: Calculating Bond Lengths

You calculate bond lengths by finding the mean/average of the given lengths. You also need to check if it is a resonance structure or not.
by Catherine Kim 3K
Thu Nov 01, 2018 3:00 pm
Forum: Ionic & Covalent Bonds
Topic: Valence electrons
Replies: 2
Views: 99

Re: Valence electrons

The electron configuration of Mn is [Ar]4s2 3d5. Therefore, it has 7 valence electrons. Also Mn is a transition metal so it would have incomplete d subshells.
by Catherine Kim 3K
Thu Nov 01, 2018 2:57 pm
Forum: Trends in The Periodic Table
Topic: Atomic radius across a period
Replies: 3
Views: 107

Re: Atomic radius across a period

Atomic radius of atoms decreases from left to right (exception is the oxygen radius being slightly greater than nitrogen radius) because protons are being added to the nucleus and so electrons are being added too. Since electrons are being pulled closer to nucleus, the size of atoms decreases.
by Catherine Kim 3K
Thu Nov 01, 2018 2:52 pm
Forum: Trends in The Periodic Table
Topic: Trends in first ionization energies
Replies: 3
Views: 76

Re: Trends in first ionization energies

First ionization energies increase from left to right on the period table. Electron shielding affects ionization energy.
by Catherine Kim 3K
Wed Oct 24, 2018 7:34 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: electron configurations
Replies: 1
Views: 64

electron configurations

Why is the electron configuration for Ytterbium [Xe]4f14 6s2 and not [Xe]4f13 5d1 6s2?
by Catherine Kim 3K
Tue Oct 23, 2018 10:30 pm
Forum: Quantum Numbers and The H-Atom
Topic: Question 2.43 6th Edition
Replies: 2
Views: 92

Re: Question 2.43 6th Edition

The rule is to write 5s e- after 4d e-. As for silver, d^10 has lower energy. A lower total energy may be achieved if an electron enters a 4d orbital instead of expected 5s orbital, if that arrangement completes a full subshell. You can find other exceptions to the building-up principle in Appendix ...
by Catherine Kim 3K
Tue Oct 23, 2018 10:12 pm
Forum: Quantum Numbers and The H-Atom
Topic: 1D.25 Seventh Edition
Replies: 2
Views: 80

Re: 1D.25 Seventh Edition

The values of l are 0 and 1 if n = 2. That means the orbital type can only be s or p.
by Catherine Kim 3K
Tue Oct 23, 2018 10:10 pm
Forum: SI Units, Unit Conversions
Topic: Expected to know?
Replies: 2
Views: 152

Re: Expected to know?

No, the value should be given in the formula sheet.
by Catherine Kim 3K
Thu Oct 18, 2018 9:21 pm
Forum: Einstein Equation
Topic: Energy of photon [ENDORSED]
Replies: 12
Views: 609

Re: Energy of photon [ENDORSED]

Yes! You would use E=hv
by Catherine Kim 3K
Thu Oct 18, 2018 9:19 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Atomic Absorption Spectroscopy versus Atomic Emission Spectroscopy
Replies: 3
Views: 76

Re: Atomic Absorption Spectroscopy versus Atomic Emission Spectroscopy

The atomic absorption spectroscopy part is correct. Yet, the emission line spectrum would be the answer to an experiment where only emitted wavelengths of light are detected.
by Catherine Kim 3K
Thu Oct 18, 2018 9:14 pm
Forum: DeBroglie Equation
Topic: post assessment #29
Replies: 2
Views: 98

Re: post assessment #29

No they will not have the same speed. They will have the same momentum. The formula of the de Broglie wavelength is λ = h/p. P = mass x velocity. An electron is lighter than a proton, so it was have a higher velocity/speed.
by Catherine Kim 3K
Wed Oct 10, 2018 7:43 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Meaning of Quanta/Quantized
Replies: 2
Views: 64

Re: Meaning of Quanta/Quantized

"Quanta" just means a packet of energy. I believe "quantized" means that the energy is divided into small packets/levels, so it can only have certain discrete values.
by Catherine Kim 3K
Wed Oct 10, 2018 7:29 pm
Forum: Limiting Reactant Calculations
Topic: Test 1 Question
Replies: 5
Views: 220

Re: Test 1 Question

You could work on the modules on Professor Lavelle's website or the practice questions you worked on with your TA. I believe the format of the test will be short answers.
by Catherine Kim 3K
Wed Oct 10, 2018 7:24 pm
Forum: *Black Body Radiation
Topic: Black Body
Replies: 10
Views: 448

Re: Black Body

According to the textbook, a black body is an object that absorbs and emits all frequencies of radiation without favor. The object that is heated, or the "hot object," is known as the black body.
by Catherine Kim 3K
Wed Oct 03, 2018 10:48 pm
Forum: Limiting Reactant Calculations
Topic: Limiting Reactant Steps General Question
Replies: 3
Views: 90

Re: Limiting Reactant Steps General Question

If you add the mass percentages of each element in a formula together, it usually equals around 100% (does not go over though). Therefore, you can assume 100g of the sample.
by Catherine Kim 3K
Wed Oct 03, 2018 10:42 pm
Forum: Student Social/Study Group
Topic: Homework Format
Replies: 3
Views: 133

Re: Homework Format

The syllabus says to make sure to clearly indicate textbook edition, chapter, and homework number.
by Catherine Kim 3K
Wed Oct 03, 2018 10:33 pm
Forum: Balancing Chemical Reactions
Topic: Balancing reactions tips
Replies: 29
Views: 878

Re: Balancing reactions tips

A tip that I use is to first balance the element that occurs the least.

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