Search found 45 matches
- Sat Dec 07, 2019 8:45 am
- Forum: DeBroglie Equation
- Topic: Quantum Help
- Replies: 5
- Views: 488
Re: Quantum Help
I find it helpful to separately write out all of the given values in a problem, and then write down the variable that I am trying to find. Then I pick an equation (or equations if it is multistep) to help me find that variable. I think it's easier to have some derivations of equations memorized too.
- Sat Dec 07, 2019 8:30 am
- Forum: Properties of Light
- Topic: Light Absorbed/ emitted
- Replies: 4
- Views: 364
Re: Light Absorbed/ emitted
Light is absorbed when energy level increases (electron gets excited). Light is emitted when energy level decreases (electron goes back to ground state).
- Sat Dec 07, 2019 8:27 am
- Forum: Properties of Light
- Topic: Speed of Light
- Replies: 7
- Views: 588
Re: Speed of Light
standard units for c are m/s
- Sat Dec 07, 2019 8:26 am
- Forum: Properties of Light
- Topic: Hz vs. frequency
- Replies: 7
- Views: 577
Re: Hz vs. frequency
Hertz is just the unit for frequency. You can denote frequency using Hz or s^-1 because they are the same.
- Sat Dec 07, 2019 8:26 am
- Forum: Properties of Light
- Topic: Frequency vs. Velocity
- Replies: 8
- Views: 794
Re: Frequency vs. Velocity
Velocity of light is the same as speed of light, c=3.00x10^8 m/s. Frequency varies and can be found through given wavelengths and/or energy in a problem.
- Sun Nov 24, 2019 2:29 pm
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: How to tell?
- Replies: 11
- Views: 870
Re: How to tell?
Acids typically have a hydrogen since it donates protons (ex: HCl). Bases will have hydroxide (OH) in their formula for you to identify (ex: sodium hydroxide: NaOH).
- Sun Nov 24, 2019 2:10 pm
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: Acids
- Replies: 13
- Views: 1479
Re: Acids
There is no specific list but it’ll be helpful to remember the 7 most common acids.
- Sun Nov 24, 2019 2:08 pm
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: Bronsted acids
- Replies: 5
- Views: 486
Re: Bronsted acids
By definition, bronsted acids donate protons and bronsted gases accept protons. When an acid and base react in an equation, the acid has a conjugate base that accepts its proton, and the base has a conjugate acid that forms when the base accepts the proton.
- Sun Nov 24, 2019 2:02 pm
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: Bronsted vs. Lewis Acids
- Replies: 9
- Views: 479
Re: Bronsted vs. Lewis Acids
Bronsted acids donate protons, but Lewis acids accept electrons.
- Wed Nov 20, 2019 11:52 am
- Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
- Topic: Ion-dipole vs Hydrogen Bonding
- Replies: 2
- Views: 270
Ion-dipole vs Hydrogen Bonding
Are hydrogen bonds stronger than ion-dipole interactions?
- Sat Nov 16, 2019 1:29 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: varying VSEPRs
- Replies: 7
- Views: 428
Re: varying VSEPRs
Shape will not vary because resonance structures don't matter in determining shape
- Sat Nov 16, 2019 1:27 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: How to tell polar or non polar from lewis structure?
- Replies: 9
- Views: 636
Re: How to tell polar or non polar from lewis structure?
Check to see if the dipoles cancel out in molecules. It helps to draw out arrows to signify the dipoles of each atom to visually see if they cancel out or not to create a polar or nonpolar molecule.
- Sat Nov 16, 2019 1:24 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: test 2
- Replies: 13
- Views: 635
Re: test 2
Only if hybridization is also on the one page of notes he has left to teach us on Monday
- Sat Nov 16, 2019 1:22 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Notation used in VSEPR
- Replies: 8
- Views: 521
Re: Notation used in VSEPR
You should know it since it was talked about in lecture, but besides that it helps you identify the different shapes of molecules with lone pairs.
- Sat Nov 16, 2019 1:09 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Determining if a molecule is polar or non polar
- Replies: 9
- Views: 800
Re: Determining if a molecule is polar or non polar
I don't think we have to know exact values of electronegativity. However, the periodic table should tell us the polarity (or lack thereof) of molecules based on the trends of electronegativity.
- Sat Nov 09, 2019 10:26 am
- Forum: Ionic & Covalent Bonds
- Topic: C, N, O, and F
- Replies: 13
- Views: 576
Re: C, N, O, and F
C, N, O, and F must follow the octet rule at all times. Atoms can begin having expanded octets at period 3 or greater. Typical atoms with expanded octets include sulfur, phosphorus, and silicon (all of which are in period 3).
- Sat Nov 09, 2019 10:23 am
- Forum: Ionic & Covalent Bonds
- Topic: Covalent character and ionic character
- Replies: 5
- Views: 316
Re: Covalent character and ionic character
The primary difference of these two types of bonds is that atoms in an ionic bond have a greater difference in electronegativity than the atoms in a covalent bond. Due to the complete oppositely charged atoms in an ionic bond, electrons are donated from one atom to the other. However, electrons in c...
- Sat Nov 09, 2019 10:15 am
- Forum: Ionic & Covalent Bonds
- Topic: Bond Strength
- Replies: 12
- Views: 974
Re: Bond Strength
Ionic bonds are stronger because the atoms have a greater difference in electronegativity than those in covalent bonds that form partial charges.
- Sat Nov 09, 2019 10:13 am
- Forum: Ionic & Covalent Bonds
- Topic: Ionization of Nitrogen vs Oxygen
- Replies: 11
- Views: 1491
Re: Ionization of Nitrogen vs Oxygen
Ionization energy does increase going left to right across a periodic table. However, comparing the electronic configuration of nitrogen and oxygen, you can see that nitrogen ends at 2p3 and oxygen is 2p4. Half or fully filled orbitals are stable, and nitrogen's 2p orbital is filled halfway so it is...
- Sat Nov 09, 2019 10:06 am
- Forum: Ionic & Covalent Bonds
- Topic: Polarizability
- Replies: 6
- Views: 409
Re: Polarizability
Polarizability is the ability of an atom to form instantaneous dipoles. Thus, when an atom has a bigger atomic radius, it's polarizability increases because there are more electrons and the electrons are more dispersed.
- Sat Nov 02, 2019 10:19 am
- Forum: Ionic & Covalent Bonds
- Topic: Anions and Cations
- Replies: 9
- Views: 418
Re: Anions and Cations
Anions are larger because when adding electrons, electron-electron repulsion increases and create a larger atomic radius. Cations lose electrons from the valence shell which make them smaller in size.
- Sat Nov 02, 2019 10:13 am
- Forum: Hybridization
- Topic: Electrons
- Replies: 13
- Views: 1201
Re: Electrons
Electron is excited and moves to the next orbital.
- Sat Nov 02, 2019 10:12 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Polar v. Nonpolar
- Replies: 11
- Views: 2035
Re: Polar v. Nonpolar
A polar molecule has polar bonds, meaning the electrons in a covalent bond is unequally shared due to one of the atoms being more strongly electronegative than the other. An example of this would be H2O, where oxygen is more electronegative than hydrogen. The unequal sharing creates dipoles, and oxy...
- Sat Nov 02, 2019 10:04 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: how to draw lewis structure
- Replies: 9
- Views: 861
Re: how to draw lewis structure
Also, many times ClO2 is associated with a negative charge, which means it would have a total of 20 electrons instead of 19.
- Sat Nov 02, 2019 9:52 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Lewis Structure
- Replies: 5
- Views: 268
Re: Lewis Structure
If there is a negative charge, then you add however many more electrons are shown in the number of the charge. Conversely, if there is a positive charge then you subtract however many number of electrons that the charge shows.
- Sat Oct 26, 2019 5:48 pm
- Forum: Trends in The Periodic Table
- Topic: blocks
- Replies: 13
- Views: 567
Re: blocks
Remembering them will help you write out electron configurations using the periodic table.
- Sat Oct 26, 2019 5:36 pm
- Forum: Trends in The Periodic Table
- Topic: types of radii
- Replies: 4
- Views: 96
Re: types of radii
All of these types of radii share the same periodic trends, however atomic radii is just specifically referring to the half distance between two atoms while covalent radii is for 2 atoms covalently bonded, and ionic is for 2 atoms with an ionic bond.
- Sat Oct 26, 2019 5:33 pm
- Forum: Trends in The Periodic Table
- Topic: Ionization energy
- Replies: 12
- Views: 524
Re: Ionization energy
I think you should know that on the periodic table, ionization energy increases going left to right across a period because atomic radius decreases, so electrons are more closely attracted to the nucleus. Going down a group, ionization energy decreases because valence electrons are shielded further ...
- Sat Oct 26, 2019 5:29 pm
- Forum: Trends in The Periodic Table
- Topic: bond length
- Replies: 9
- Views: 390
Re: bond length
I don't think we have to know exact bond lengths, but it may be helpful to keep in mind that single bonds are longer than double bonds which are longer than triple bonds (triple bond length<double bond length<single bond length, so triple bonds are shortest).
- Sat Oct 26, 2019 5:21 pm
- Forum: Trends in The Periodic Table
- Topic: Electronegativity vs Electron Affinity
- Replies: 6
- Views: 256
Re: Electronegativity vs Electron Affinity
Electronegativity is the tendency of an atom to to attract electrons to itself, and it increases as you move left to right across a periodic table and decreases down a group. Electron affinity is mainly referring to the amount of energy released when an electron is added to an atom. Its periodic tre...
- Sat Oct 19, 2019 9:16 am
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: writing electron configurations?
- Replies: 4
- Views: 123
Re: writing electron configurations?
You can look up a periodic table that is color coded orbital, and use that to guide you through the configurations. Typically, the elements in the first 2 groups are s orbitals, 3-12 is d orbital, and 13-18 (excluding Helium witch is s-orbital) are p-orbitals. For example, to find the electron confi...
- Sat Oct 19, 2019 9:01 am
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Hund's Rule
- Replies: 4
- Views: 251
Re: Hund's Rule
Hund's Rule states that electrons try to fill up orbitals separately and only pair when necessary because the like negative charges tend to repel. Think of it like this, if you have a sibling who was annoying you, you wouldn't share a room with them unless you absolutely had to; electrons are the sa...
- Sat Oct 19, 2019 8:57 am
- Forum: DeBroglie Equation
- Topic: De Broglie's Equation
- Replies: 17
- Views: 526
Re: De Broglie's Equation
You need to have mass to use the De Broglie Equation, however photons of light do not have mass.
- Sat Oct 19, 2019 8:51 am
- Forum: Properties of Light
- Topic: Unit for Wavelength
- Replies: 34
- Views: 2193
Re: Unit for Wavelength
Wavelength is measured in meters, however some questions give or ask for the wavelength in nanometers. In the case that it does give nanometers of wavelength, just make sure to convert it to meters (nm x 10^-9) so that you can get the correct answer since the speed of light also has a unit of m/s an...
- Sat Oct 19, 2019 8:47 am
- Forum: Properties of Light
- Topic: Equations and Constants
- Replies: 6
- Views: 222
Re: Equations and Constants
Most constants (Rydberg's, Planck's, etc.), equations (c = λ ν, E = h ν, etc.) are given on the sheet. However, you can figure out (or memorize) derivations of some equations that are not given.
- Sat Oct 12, 2019 1:06 pm
- Forum: Properties of Electrons
- Topic: De Broglie Problems
- Replies: 4
- Views: 114
Re: De Broglie Problems
A particle with a De Broglie wavelength of less than 10^-15 m does not have very detectable wavelike particles.
- Sat Oct 12, 2019 1:01 pm
- Forum: Photoelectric Effect
- Topic: Photoelectric Effect
- Replies: 3
- Views: 138
Photoelectric Effect
When subtracting energy removed from energy of a photon, why is the resulting excess energy also equal to kinetic energy of the electron?
- Sat Oct 12, 2019 12:59 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: H-Atom
- Replies: 3
- Views: 150
H-Atom
Is spectroscopy only valid to identify H-atoms or can it be used to identify other atoms as well?
- Sat Oct 12, 2019 12:57 pm
- Forum: Photoelectric Effect
- Topic: Rydberg Constant
- Replies: 1
- Views: 77
Rydberg Constant
Can you use electromagnetic radiation equations when using the Rydberg constant equation to find wavelength?
- Sat Oct 12, 2019 12:52 pm
- Forum: Photoelectric Effect
- Topic: Molecular Spectroscopy
- Replies: 3
- Views: 136
Molecular Spectroscopy
Why can molecular spectroscopy not be used to identify molecules?
- Thu Oct 03, 2019 10:42 am
- Forum: Significant Figures
- Topic: How Many significant figures to use ?
- Replies: 9
- Views: 3177
Re: How Many significant figures to use ?
The general rule is to round your final answer at the end to the same number of significant figures as the number with the least digits. Try not to round your answers before your final answer, though. Otherwise, your answer will not be as accurate as you want it to be.
- Thu Oct 03, 2019 10:36 am
- Forum: Significant Figures
- Topic: Calculators
- Replies: 20
- Views: 1693
Re: Calculators
The syllabus states that "only non-programmable, non-graphing calculators are allowed." Buy one and use it for the test.
- Thu Oct 03, 2019 10:33 am
- Forum: Significant Figures
- Topic: Rounding Sig Figs
- Replies: 4
- Views: 114
Re: Rounding Sig Figs
You could write out the numbers before the final answer out at least 6 decimal places to get a more accurate final answer. Make sure you only round your answer to the correct number of sig figs at the end of the entire problem. If you round before, your answer will be farther off from from exact cal...
- Thu Oct 03, 2019 10:30 am
- Forum: Significant Figures
- Topic: Powers of 10
- Replies: 10
- Views: 561
Re: Powers of 10
Can someone explain when we know to write answers in powers of 10 and when it's not necessary? Scientific notation is most typically used when the number of zeros in a number is too long to write out (usually starting around 3 or 4 decimal zeros before or after the first non-zero number). For exampl...
- Thu Oct 03, 2019 10:25 am
- Forum: Significant Figures
- Topic: rounding in sig figs
- Replies: 5
- Views: 309
Re: rounding in sig figs
You would round up to to .457. When the digit before the number of sig figs you are rounding to is greater than 5, you round up. If the digit is less than 5, you round down.