Search found 32 matches

by Jack Martinyan 1L
Sun Jun 10, 2018 11:29 am
Forum: Bronsted Acids & Bases
Topic: 12.27
Replies: 1
Views: 164

Re: 12.27

M1V1=M2V2

(0.025)(200)=(M2)(250)

M2= (0.025)(200)/250

M2 is the concentration of the H30+

pH=-log[H3O+]

pH=-log[(0.025)(200)/250]
by Jack Martinyan 1L
Wed Jun 06, 2018 1:26 pm
Forum: Ionic & Covalent Bonds
Topic: Ionic Bonds vs Covalent Bonds
Replies: 7
Views: 147

Re: Ionic Bonds vs Covalent Bonds

Ionic bonds tend to be stronger than covalent bonds due to the coulombic attraction between ions of opposite charges
by Jack Martinyan 1L
Mon Jun 04, 2018 9:33 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angle [ENDORSED]
Replies: 4
Views: 220

Re: Bond Angle [ENDORSED]

Exact bond angles cannot be obtained from VSEPR. Exact bond angles are obtained from experimental data.
by Jack Martinyan 1L
Sun Jun 03, 2018 10:57 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: AXE formula
Replies: 18
Views: 616

Re: AXE formula

The chart below will be helpful
by Jack Martinyan 1L
Sat Jun 02, 2018 6:09 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Ligands
Replies: 8
Views: 203

Re: Ligands

Ligands have at least one donor atom with an electron pair used to form covalent bonds with the central atom.
by Jack Martinyan 1L
Sat Jun 02, 2018 6:05 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: formal charge and VSEPR
Replies: 8
Views: 173

Re: formal charge and VSEPR

Yes, I believe the best habit to keep in mind is to draw the lewis structure with the lowest formal charge before applying VSEPR
by Jack Martinyan 1L
Fri May 25, 2018 9:00 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular geometry vs. shape [ENDORSED]
Replies: 1
Views: 97

Re: Molecular geometry vs. shape [ENDORSED]

Geometry refers to the arrangement of the electron groups, while shape refers to the overall shape of the molecule. Both are given by the VSEPR theory, but they are not the same thing. VSEPR electron pair arrangement and molecular shape are not the same when a central atom possesses non-bonding elec...
by Jack Martinyan 1L
Fri May 25, 2018 8:51 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: HW 4.13
Replies: 2
Views: 90

Re: HW 4.13

When you draw the Lewis structure of the I3- ion, you end up with two iodines attached to a central iodine. The central iodine also has three lone pairs on it. This gives you 5 regions of electron density around the central atom. This gives a trigonal bipyramidal shape. The electron pairs repel each...
by Jack Martinyan 1L
Sat May 19, 2018 8:04 pm
Forum: Lewis Structures
Topic: XeO2F2 Lewis Structure [ENDORSED]
Replies: 1
Views: 85

Re: XeO2F2 Lewis Structure [ENDORSED]

Beginning with the n=3 principle quantum number, the d orbitals become available (l=2). Because of this, Xe can have more than an octet. While drawing the lewis structure, we are looking for the structure with a formal charge closest to zero. This is why Xe has 12 electrons instead of eight.
by Jack Martinyan 1L
Tue May 15, 2018 4:10 pm
Forum: Lewis Structures
Topic: Central atom
Replies: 7
Views: 174

Re: Central atom

Carbon would go in the middle because it has the lowest ionization energy
by Jack Martinyan 1L
Mon May 14, 2018 9:01 pm
Forum: Coordinate Covalent Bonds
Topic: format
Replies: 1
Views: 176

Re: format

I believe the line with the arrow is the standard notation
by Jack Martinyan 1L
Mon May 14, 2018 8:56 pm
Forum: Lewis Structures
Topic: BF3
Replies: 2
Views: 89

Re: BF3

The two elements that most commonly fail to complete an octet are boron and aluminum; they both readily form compounds in which they have six valence electrons, rather than the usual eight predicted by the octet rule. I believe these two are the most common ones
by Jack Martinyan 1L
Sat May 12, 2018 1:56 pm
Forum: Trends in The Periodic Table
Topic: electron affinity vs electronegativity?
Replies: 2
Views: 461

Re: electron affinity vs electronegativity?

Electronegativity is the ability of an atom to attract electrons from outside. This is a qualitative property of an atom, and in order to compare the electronegativities of atoms in each element, a scale where relative electronegativity values reside is used. This scale is called “Pauling scale.” Ac...
by Jack Martinyan 1L
Sat May 12, 2018 1:40 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal charge of ClO2- [ENDORSED]
Replies: 4
Views: 196

Re: Formal charge of ClO2- [ENDORSED]

I found a video that goes through the step by step process of identifying the formal charge and drawing the lewis structure for ClO2-

https://www.youtube.com/watch?v=GTKW7nDzVCA
by Jack Martinyan 1L
Thu May 10, 2018 1:27 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: energy emitted
Replies: 2
Views: 122

Re: energy emitted

The first equation is used to calculate the frequency of the emitted light when electrons transition between energy levels. When light is absorbed, the transition is up to a higher energy level. When light is emitted, the transition is down to a lower energy level. The calculation is always done usi...
by Jack Martinyan 1L
Thu May 10, 2018 1:17 pm
Forum: Resonance Structures
Topic: Resonance Structures and Formal charges
Replies: 7
Views: 206

Re: Resonance Structures and Formal charges

Lewis structures incorporate an atom's formal charge, which is the charge on an atom in a molecule, assuming that electrons in a chemical bond are shared equally between atoms. When multiple Lewis structures can represent the same compound, the different Lewis formulas are called resonance structures.
by Jack Martinyan 1L
Sun May 06, 2018 11:56 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: F orbital
Replies: 6
Views: 237

Re: F orbital

A good conceptual concept to remember is that a shell is bigger than a sub shell which is bigger than an orbital

Shell > Subshell > orbital
by Jack Martinyan 1L
Wed May 02, 2018 9:42 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: 2.19 part d
Replies: 2
Views: 75

Re: 2.19 part d

The value of n determines the possible values for l. For any given shell, the number of subshells can be found by l = 0,.....,n-1. In the case of n=4, l=0,1,2,3. This tells us that there are 4 possible sub-shells (0,1,2,3). When l is 0, then the orbital is s. When l is 1, then the orbital is p. When...
by Jack Martinyan 1L
Wed May 02, 2018 9:31 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Question 2.13
Replies: 2
Views: 81

Re: Question 2.13

In Outline 2, it states that we must be able to "describe and identify s-, p-, and d-orbitals.". What you mentioned does suffice in terms of what we should know about the orientation along the different axes. One thing to keep in mind is that the p orbital has nodal planes, unlike the s or...
by Jack Martinyan 1L
Sun Apr 29, 2018 8:45 pm
Forum: DeBroglie Equation
Topic: Quanta
Replies: 5
Views: 189

Re: Quanta

Electrons exist on specific energy levels and cannot exist in between them. When an electron moves to another energy level, it must release or absorb very specific amounts of energy. This is what quantized means: the amount of energy absorbed or released can only be specific quantities called quanta
by Jack Martinyan 1L
Sun Apr 22, 2018 9:49 pm
Forum: DeBroglie Equation
Topic: 1.39 and 1.23
Replies: 3
Views: 109

Re: 1.39 and 1.23

It will be on the cover sheet. Conversion from eV to J, certain constants, and masses of particles will be there.
by Jack Martinyan 1L
Sat Apr 21, 2018 11:46 pm
Forum: DeBroglie Equation
Topic: equations that apply to light only/everything else but light
Replies: 8
Views: 244

Re: equations that apply to light only/everything else but light

The photon is a massless particle. According to theory it has energy and momentum but no mass, and this is confirmed by experiments. Light carries momentum and will exert pressure on a surface. This is not evidence that it has mass since momentum can exist without mass. Sometimes people like to say ...
by Jack Martinyan 1L
Thu Apr 19, 2018 2:05 pm
Forum: DeBroglie Equation
Topic: HW 1.37 [ENDORSED]
Replies: 6
Views: 249

Re: HW 1.37 [ENDORSED]

After finding the values of both the wavelengths for the proton and the neutron, subtract the wavelength of the neutron from the wavelength of the proton. After you find the difference, multiply the difference by 100 and divide it by the wavelength of the neutron to find out what percentage of the n...
by Jack Martinyan 1L
Wed Apr 18, 2018 8:37 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: The Negative Sign in En = -hR/n^2
Replies: 5
Views: 130

Re: The Negative Sign in En = -hR/n^2

The negative sign implies that the bound electron has lower energy than the free electron. The eletron's energy has decreased, and the energy is released as electromagnetic radiation
by Jack Martinyan 1L
Wed Apr 18, 2018 8:23 pm
Forum: DeBroglie Equation
Topic: 10^-18
Replies: 3
Views: 84

Re: 10^-18

The electromagnetic spectrum (EMS) is the general name given to the known range of electromagnetic radiation. Wavelengths increase from approximately 10^-18 m to 100 km, and this corresponds to frequencies decreasing from 3 × 10^26 Hz to 3 ×10^3 Hz. The smallest electromagnetic waves we know about a...
by Jack Martinyan 1L
Sat Apr 14, 2018 6:21 pm
Forum: SI Units, Unit Conversions
Topic: Length Units
Replies: 15
Views: 438

Re: Length Units

Stick to the SI units, unless a question asks for a specific type of unit.
by Jack Martinyan 1L
Sat Apr 14, 2018 12:53 pm
Forum: SI Units, Unit Conversions
Topic: SI Units- Bond Length [ENDORSED]
Replies: 1
Views: 194

Re: SI Units- Bond Length [ENDORSED]

Bond lengths have traditionally been expressed in Ångstrom units (1Å = 10^-10 m), but picometers are now preferred (1 pm= 10^-12m ). We use these units because the bond length is a very small length. Also, it is more efficient to use 1pm than to constantly write out 10^-12m.
by Jack Martinyan 1L
Sun Apr 08, 2018 12:30 pm
Forum: SI Units, Unit Conversions
Topic: writing out conversions in one long line vs. steps
Replies: 16
Views: 494

Re: writing out conversions in one long line vs. steps

There is no right or wrong way, as long as you get to the same answer with the right units. It is totally up to preference. However, writing out the conversions in one lone line will make it easier to visualize the dimensional analysis as you cross out all your units to eventually arrive at your des...
by Jack Martinyan 1L
Sun Apr 08, 2018 12:08 pm
Forum: General Science Questions
Topic: Rusty on High School Chem [ENDORSED]
Replies: 113
Views: 34689

Re: Rusty on High School Chem [ENDORSED]

Best Resources:

1. All the resources Dr. Lavelle provides on a weekly basis
2. Khan Academy
3. Crash Course
4. Bozeman Science
5. Your friend who's a chem wiz
by Jack Martinyan 1L
Sun Apr 08, 2018 12:00 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Dimensional Analysis Help [ENDORSED]
Replies: 6
Views: 254

Re: Dimensional Analysis Help [ENDORSED]

Dimensional Analysis is a great way to keep track of all your units to make sure that everything crosses out at the end, leaving you with your desired units. The easiest way to perform it is by basically multiplying all your quantities at the same time in one line to see which units cross out. This ...
by Jack Martinyan 1L
Sun Apr 08, 2018 11:42 am
Forum: SI Units, Unit Conversions
Topic: why do I not use avogadro's number
Replies: 5
Views: 180

Re: why do I not use avogadro's number

You can use avogadro's number to solve the problem; however, it would take longer and woudn't be as productive. In this case, it's much easier to just divide the mass of the sample by the mass of the individual atom to get the number of atoms since we already have both values: mass(sample) / mass(at...

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