## Search found 45 matches

Sat Dec 07, 2019 8:45 am
Forum: DeBroglie Equation
Topic: Quantum Help
Replies: 5
Views: 203

### 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: 208

### 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: 268

### 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: 244

### 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: 260

### 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: 486

### 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: 256

### 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: 153

### 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: 120

### 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: 54

### 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: 133

### 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: 160

### 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: 182

### 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: 154

### 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: 314

### 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: 190

### 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: 96

### 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: 252

### 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: 189

### 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: 137

### 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: 181

### 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: 680

### 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: 1510

### 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: 439

### 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: 86

### 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: 159

### 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
Replies: 4
Views: 57

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: 217

### 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: 124

### 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: 100

### 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: 52

### 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: 89

### 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: 276

### 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: 437

### 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: 105

### 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: 53

### 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: 93

### 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: 81

### 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: 45

### 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: 88

### 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: 218

### 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: 975

### 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: 73

### 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: 155

### 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: 238

### 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.