Search found 30 matches

by Andonios Karas 4H
Wed Nov 28, 2018 7:47 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Polydentates
Replies: 3
Views: 116

Re: Polydentates

This question was posed previously on Chem Community. Answer: The oxygen atoms is on the opposite side. If you visualize it, there is no way for it to be bound to all of the oxygen atoms at one. It can barely bind to 2 at once. Hence, it can be mono or bidentate. https://www.researchgate.net/profile...
by Andonios Karas 4H
Wed Nov 28, 2018 7:41 pm
Forum: Hybridization
Topic: Sp3d or dsp3
Replies: 4
Views: 158

Re: Sp3d or dsp3

This question was answered by a Chem_Mod before. Question: When writing the hybridization of an atom is it better to write it like "dsp3" or "sp3d"? Do you have a preference? Answer: Either is ok. But sp3d is preferred. https://lavelle.chem.ucla.edu/forum/viewtopic.php?t=1256
by Andonios Karas 4H
Wed Nov 28, 2018 7:35 pm
Forum: Naming
Topic: Cyano vs. Cyanido
Replies: 2
Views: 138

Re: Cyano vs. Cyanido

This question was answered previously by a Chem_Mod.

Answer: They are actually the same ligand, but the the first (cyano) is an older naming convention. Cyanido is the IUPAC preferred name for the ligand.

https://lavelle.chem.ucla.edu/forum/viewtopic.php?t=2351
by Andonios Karas 4H
Mon Nov 26, 2018 6:32 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: Test 3
Replies: 2
Views: 89

Re: Test 3

According to the website, Test 3 covers: End of Bonding from 3.12 (6 Ed.) and from 2D (7 Ed.); and all of Molecular Shape and Structure (see Syllabus and Outlines for details). 2D covers Intra-Molecular Forces or Bonds. 3F covers Inter-Molecular Forces like London forces, Hydrogen Bonding, Dipole-Di...
by Andonios Karas 4H
Mon Nov 26, 2018 6:10 pm
Forum: Ionic & Covalent Bonds
Topic: Polar Molecule
Replies: 3
Views: 169

Re: Polar Molecule

Whether a molecule is nonpolar or polar depends on the net dipole moment, not the formal charges. A dipole can be determined by looking at the electronegativity of two atoms that are bonded. The more electronegative atom will pull more on the electrons, leading to a dipole. After the 3D structure is...
by Andonios Karas 4H
Mon Nov 26, 2018 5:59 pm
Forum: Dipole Moments
Topic: Homework Question 3F.1
Replies: 1
Views: 73

Re: Homework Question 3F.1

All molecules and atoms can have London forces occur between them due to the rapid fluctuations of electron distribution interacting between two molecules or atoms. It can occur if the molecules are both polar, both nonpolar, or one nonpolar and one polar. Hydrogen Bonding is always a Dipole-Dipole ...
by Andonios Karas 4H
Mon Nov 26, 2018 5:34 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 4.19 6th Edition
Replies: 2
Views: 61

Re: 4.19 6th Edition

Boron is an exception to the octet rule and is content with having only 6 electrons in its valence shell. Therefore, when drawing the Lewis Structure of BH 2 - , you should have 3 regions of electron density. Two in the form of B-H bonds and one as a lone pair on Boron. Because it has 3 regions of e...
by Andonios Karas 4H
Mon Nov 26, 2018 5:28 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Octahedral
Replies: 3
Views: 57

Re: Octahedral

The bond angles for octahedral molecular geometry are 90 o and 180 o . Whenever an long pair of electrons replaces a bonding pair, it will exert forces on adjacent bonding pairs and cause angles to become less than 90 o . Here is an image describing each electron geometry and angle size. https://s3-...
by Andonios Karas 4H
Mon Nov 26, 2018 5:19 pm
Forum: Naming
Topic: Ligand
Replies: 4
Views: 95

Re: Ligand

A ligand is any ion or molecule attached to a metal atom by coordinate bonding to form a complex. A ligand is almost always a Lewis Base and donates a lone pair to the central metal atom; however there are rare cases of Lewis Acids acting as ligands. For example, Nitrogen in :NH 3 can be a ligand be...
by Andonios Karas 4H
Tue Nov 13, 2018 7:35 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 7th Edition 2E #21 part d
Replies: 1
Views: 37

Re: 7th Edition 2E #21 part d

Each N atom, which has 5 valence electrons, is bonded to 3 atoms: 2 H and 1 N (each with only single bonds). Now, we must count how many lone pairs and bonding pairs there are for each N atom which comes out to be 3 bonding pairs and 1 lone pair. The 1 lone pair will repel the bonding pairs away fro...
by Andonios Karas 4H
Tue Nov 13, 2018 7:14 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Visualizing Molecules
Replies: 1
Views: 45

Re: Visualizing Molecules

There is a website called http://molview.org where you can create lewis structures and see the 3-D model.
by Andonios Karas 4H
Thu Nov 08, 2018 11:49 am
Forum: Dipole Moments
Topic: H2O and H2O intermolecular forces
Replies: 1
Views: 115

Re: H2O and H2O intermolecular forces

A hydrogen bond is a dipole-dipole interaction between two water molecules. Due to the differing electronegativies, the oxygen atom will have a slightly negative charge and hydrogen atoms will have slightly positive charges in water. Therefore, water is a dipole as electrons are pulled more towards ...
by Andonios Karas 4H
Thu Nov 08, 2018 11:41 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configuration for Ions
Replies: 2
Views: 128

Electron Configuration for Ions

Scandium = [Ar] 3d1 4s2 Scandium 2+ = [Ar] 3d1 My question regarding these electron configurations is why does the electron remain in the 3d shell for the ion instead of moving the the 4s shell. For potassium keeps its one valence electron in the 4s shell because the electron is at a lower energy le...
by Andonios Karas 4H
Thu Nov 08, 2018 11:08 am
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge & Stable lewis structures
Replies: 6
Views: 168

Re: Formal Charge & Stable lewis structures

It is best to reduce the the formal charges overall because it lowers the difference in formal charge between two atoms in a molecule, which is more stable. For example, having one 2+ atom surrounded by two 1- atoms is typically less stable than all the atoms have a formal charge of zero. Additional...
by Andonios Karas 4H
Tue Nov 06, 2018 5:26 pm
Forum: Ionic & Covalent Bonds
Topic: Greater Ionic Character? [ENDORSED]
Replies: 3
Views: 111

Re: Greater Ionic Character? [ENDORSED]

And if you need a reference for the electronegativity of each atom that the book is basing its solutions off of, look at figure 2D.2 in the 7th edition. IMG_0506.jpg Going by what Krista pointed out, we can see whether that HCl (difference in electronegativity is 0.96) has more ionic character than ...
by Andonios Karas 4H
Thu Nov 01, 2018 12:16 am
Forum: Trends in The Periodic Table
Topic: Electron Affinity and Eletronegativity
Replies: 1
Views: 150

Re: Electron Affinity and Eletronegativity

You are correct in saying that they do follow the same trends. Electron Affinity is the measurable amount of energy released or needed to add an electron to an atom Electronegativity is a construct made to help describe the reactivity of an atom which is based upon its willingness to pull electrons ...
by Andonios Karas 4H
Thu Nov 01, 2018 12:10 am
Forum: Trends in The Periodic Table
Topic: Electron affinity homework 1F.11
Replies: 2
Views: 144

Re: Electron affinity homework 1F.11

For this question, the book is going off the electron affinities from the figure 1F.12 which shows the electron affinities of different elements. Electron affinity doesn't directly follow a trend in the periodic table except that energies are highest towards the right side of the periodic table.
by Andonios Karas 4H
Thu Nov 01, 2018 12:03 am
Forum: Ionic & Covalent Bonds
Topic: Question 2A.23 7th Edition
Replies: 1
Views: 81

Re: Question 2A.23 7th Edition

You know the charges of monatomic cations from group 1,2, and 13 by looking at the number of valence electrons. They want to lose enough electrons to have the same electron configuration as the previous noble gas. So +1,+2, and +3 respectively. The charges of monatomic cations from groups 3 through ...
by Andonios Karas 4H
Tue Oct 23, 2018 7:24 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configurations
Replies: 2
Views: 82

Re: Electron Configurations

No, the correct electron configuration for tungsten is [Xe] 4f14 5d4 6s2. You write the electron configuration in order to lowest energies to highest energy shells. A 4f shell is lower energy than a 5d shell. A 5d shell is lower energy than a 6s shell. First, write the first noble gas with a lower a...
by Andonios Karas 4H
Tue Oct 23, 2018 4:20 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Rydberg & Bohr
Replies: 2
Views: 138

Re: Rydberg & Bohr

The Bohr Frequency Condition, \nu = \frac{\Delta E}{h} , states that the frequency is directly related to the energy of photons emitted as electrons move down energy levels. The higher the frequency, the greater the energy in each photon. Rydberg's Equation, E n = \frac{-hR}{n^{2}} , is used to calc...
by Andonios Karas 4H
Tue Oct 23, 2018 3:29 pm
Forum: Quantum Numbers and The H-Atom
Topic: Question 2.43 6th Edition
Replies: 2
Views: 92

Re: Question 2.43 6th Edition

Silver is one of the few exceptions to the common rule. While filling the s-orbital then filling the d-orbital typically achieves the lowest energy state for an atom, Silver, among other elements like Chromium and Copper, has a lower energy state with only 1 electron in the s-orbital and a full d-or...
by Andonios Karas 4H
Tue Oct 16, 2018 9:49 pm
Forum: Einstein Equation
Topic: 1B 9 7th edition
Replies: 2
Views: 86

Re: 1B 9 7th edition

64 Joules is the total energy emitted by the lamp in 2 seconds.
4.7 x 10^-19 Joules is the energy per photon emitted.
We want to know the number of photons emitted in those 2 seconds.
Etotal = Ephoton * #photons
Therefore, #photons = Etotal/Ephoton
by Andonios Karas 4H
Tue Oct 16, 2018 9:34 pm
Forum: Properties of Electrons
Topic: Example 1B.3
Replies: 2
Views: 69

Re: Example 1B.3

9.109E-31 kg is the mass of one electron, a known quantity through previous experiments. In this experiment, the kinetic energy of the electrons being ejected from the metal by photons is being calculated.
by Andonios Karas 4H
Wed Oct 10, 2018 6:17 pm
Forum: Photoelectric Effect
Topic: Threshold Energy Question
Replies: 2
Views: 58

Re: Threshold Energy Question

You are correct the work function is the energy need to remove one electron. However the number provided to you is in kiloJoules per Mole . The problem is asking for the J per Atom . You need to divide by Avogadro's number (6.022 x 10^23) and multiply by 1000 Joules in order to get the joules per on...
by Andonios Karas 4H
Wed Oct 10, 2018 6:08 pm
Forum: Molarity, Solutions, Dilutions
Topic: Textbook formula
Replies: 1
Views: 252

Re: Textbook formula

In this equation m = cMV, m = mass of solute, c = molarity of solution, M = molar mass of the solute, and V = volume of the solution. I see how this equation can be confusing when we usuall use the capital M to denote molarity of the solution. The equation is used to solve for the mass of solute nee...
by Andonios Karas 4H
Wed Oct 10, 2018 6:00 pm
Forum: Properties of Light
Topic: Problem number 1.23 [ENDORSED]
Replies: 3
Views: 75

Re: Problem number 1.23 [ENDORSED]

1 kiloelectronvolt (keV) = 1.60218 x 10^-16 joules (j). Simple multiply by the ratio and cancel out units properly to get the answer in joules.
by Andonios Karas 4H
Wed Oct 03, 2018 3:46 pm
Forum: Limiting Reactant Calculations
Topic: Limiting Reactant Question
Replies: 2
Views: 64

Re: Limiting Reactant Question

While this likely won't appear in a practice problem, there could be multiple limiting reactants in a chemical reaction with more than two reactants. In this rare case, just choose one of the limiting reactants for calculating moles of product because they will provide the same answer. Also, if you ...
by Andonios Karas 4H
Wed Oct 03, 2018 3:31 pm
Forum: Limiting Reactant Calculations
Topic: Syllabus/Homework
Replies: 1
Views: 92

Re: Syllabus/Homework

L and M are considered review on past topics. L is review on stoichiometry while M is review on limiting reactants. These topics are covered during week 1 lecture.
by Andonios Karas 4H
Wed Oct 03, 2018 3:26 pm
Forum: Molarity, Solutions, Dilutions
Topic: Dilutions
Replies: 3
Views: 115

Re: Dilutions

Yes, that would be the correct way to calculate the molarity of the solution.

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