Search found 52 matches

by chrischyu4a
Sat Dec 07, 2019 4:39 pm
Forum: Biological Examples
Topic: Hydrogen Bonding sites
Replies: 8
Views: 61

Re: Hydrogen Bonding sites

Each hydrogen that is attached to either N, O, or F counts as a potential binding site and every lone pair on a N, O, or F atom
by chrischyu4a
Sat Dec 07, 2019 4:26 pm
Forum: Calculating the pH of Salt Solutions
Topic: pH formula?
Replies: 21
Views: 526

Re: pH formula?

pH=-log[H3O+]
by chrischyu4a
Sat Dec 07, 2019 4:23 pm
Forum: Calculating the pH of Salt Solutions
Topic: pH vs. pOH
Replies: 17
Views: 183

Re: pH vs. pOH

pH is a measure of hydrogen ion concentration while pOH is a measure of hydroxide ion concentration.
by chrischyu4a
Sat Dec 07, 2019 4:20 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Calculating pH
Replies: 1
Views: 28

Re: Calculating pH

if you are given the concentration of hydronium ions in a solution then pH= -log[H3O+]. If you are given the concentration of hydroxide ions then pH=-log[OH-]
by chrischyu4a
Sat Dec 07, 2019 3:18 pm
Forum: Lewis Acids & Bases
Topic: Concept of Acid and Bases
Replies: 1
Views: 28

Re: Concept of Acid and Bases

Lewis acids would actually have more protons than lewis bases since the definition for a lewis acid is that it accepts electron pairs while lewis bases donate electron pairs
by chrischyu4a
Fri Nov 29, 2019 2:33 am
Forum: Lewis Acids & Bases
Topic: HCl vs HF
Replies: 19
Views: 128

Re: HCl vs HF

Chlorine has a larger atomic radius than Fluorine which makes it easier for chlorine to lose its hydrogen atom making it a stronger acid than fluorine.
by chrischyu4a
Fri Nov 29, 2019 2:28 am
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Strength and Weakness
Replies: 12
Views: 390

Re: Strength and Weakness

the strength of an acid is indicated by its Ka. The higher the Ka, the more it dissociates which means that it is a stronger acid
by chrischyu4a
Fri Nov 29, 2019 2:24 am
Forum: Naming
Topic: Oxidation
Replies: 14
Views: 143

Re: Oxidation

Oxidation numbers indicate the number of electrons gained or lost by an atom in a molecule
by chrischyu4a
Fri Nov 29, 2019 2:19 am
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Acid Strength
Replies: 6
Views: 67

Re: Acid Strength

Besides memorizing the list of strong acids, they are also usually associated with longer and weaker bonds which indicates that it gives up hydrogen atoms easier.
by chrischyu4a
Fri Nov 29, 2019 2:16 am
Forum: Conjugate Acids & Bases
Topic: Acids and Bases
Replies: 10
Views: 76

Re: Acids and Bases

Equilibrium arrows are used in reactions in which weak acids and bases are involved since they do not dissociate completely.
by chrischyu4a
Fri Nov 22, 2019 6:49 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: How to tell?
Replies: 11
Views: 332

Re: How to tell?

Acids usually contain hydrogen since acids are defined as substances that donate hydrogen ions.
by chrischyu4a
Fri Nov 22, 2019 6:43 pm
Forum: Hybridization
Topic: Valance Bond Theory
Replies: 2
Views: 30

Re: Valance Bond Theory

Valence bond theory basically states how atoms bond together through the combination of half filled orbitals to form hybrid orbitals which then create sigma and pi bonds.
by chrischyu4a
Fri Nov 22, 2019 6:37 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Induced dipoles
Replies: 7
Views: 384

Re: Induced dipoles

Electrons randomly distribute around a nucleus continuously. By that logic there are moments when there are more electrons concentrated in one area than another which creates a slightly uneven charge distribution which will cause a momentary dipole at one instantaneous second.
by chrischyu4a
Fri Nov 22, 2019 6:33 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Condition for pi bond
Replies: 4
Views: 46

Re: Condition for pi bond

No because pi bonds are formed in the presence of p orbitals and p orbitals are always preceded by s orbitals which create sigma bonds
by chrischyu4a
Fri Nov 22, 2019 6:31 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Sigma and Pi Bonds
Replies: 15
Views: 133

Re: Sigma and Pi Bonds

You just need to know that triple bonds consist of one sigma bond and two pi bonds
by chrischyu4a
Fri Nov 15, 2019 5:24 pm
Forum: Ionic & Covalent Bonds
Topic: Hydrogen Bond Strength
Replies: 8
Views: 76

Re: Hydrogen Bond Strength

Hydrogen bonds are weaker than ionic and covalent bonds mainly because hydrogen bonds are an intermolecular force while ionic and covalent bonds are an intramolecular force which are generally way stronger than intermolecular forces.
by chrischyu4a
Fri Nov 15, 2019 5:22 pm
Forum: Ionic & Covalent Bonds
Topic: Why is the ionization energy of nitrogen higher than that of oxygen's?
Replies: 11
Views: 109

Re: Why is the ionization energy of nitrogen higher than that of oxygen's?

When you look at the electron configurations for nitrogen and oxygen you can see that oxygen has one group of paired electrons. Due to the electron electron repulsions that occur as a result of the paired electrons, it is pushed to a higher energy level which causes it to require less energy to remo...
by chrischyu4a
Fri Nov 15, 2019 5:19 pm
Forum: Ionic & Covalent Bonds
Topic: London Dispersion
Replies: 13
Views: 104

Re: London Dispersion

All molecules have london dispersion forces due to the randomized dispersion of electrons at a singular moment which can strengthen the dipole towards a certain direction due an increased density of electrons.
by chrischyu4a
Fri Nov 15, 2019 5:17 pm
Forum: Ionic & Covalent Bonds
Topic: Bond Strength
Replies: 8
Views: 67

Re: Bond Strength

Ionic is stronger than covalent bonds since they have a greater attraction towards each other due to the opposite charges that ionic bonds possess that covalent bonds don't
by chrischyu4a
Fri Nov 15, 2019 5:13 pm
Forum: Ionic & Covalent Bonds
Topic: Types of Covalent Bonds
Replies: 4
Views: 39

Re: Types of Covalent Bonds

Polar bonds are stronger than nonpolar bonds. Coordinate covalent bonds are generally weaker than ionic/covalent bonds.
by chrischyu4a
Fri Nov 08, 2019 3:36 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: Hydrogen bonding specificity
Replies: 3
Views: 29

Re: Hydrogen bonding specificity

Hydrogen bonds only form between N, O, and F due to its high electronegativity. The high electronegativity results in an increased negative charge in those atoms which heavily attracts H atoms in adjacent molecules.
by chrischyu4a
Fri Nov 08, 2019 3:34 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: Interaction Potential Energy
Replies: 3
Views: 33

Re: Interaction Potential Energy

alpha represents the polarizability of the atom which correlates with the amount of electrons that are present in the molecule. This is because more electrons allow for more distribution around the molecule which can create stronger momentary dipoles between other molecules. r represents the distanc...
by chrischyu4a
Thu Nov 07, 2019 1:38 pm
Forum: Bond Lengths & Energies
Topic: Bond strengths
Replies: 9
Views: 60

Re: Bond strengths

Usually when a bond is shorter it is stronger, because there are more electrons that are shared between ions which result in a stronger pull between the electrons and the atoms' nuclei. The same goes for why a longer bond is weaker.
by chrischyu4a
Thu Nov 07, 2019 1:33 pm
Forum: Octet Exceptions
Topic: Easy way to remember octet exceptions
Replies: 4
Views: 49

Re: Easy way to remember octet exceptions

Also it is helpful to check the formal charge on the central ion as expanded octets usually contribute to decreasing the formal charge to 0.
by chrischyu4a
Thu Nov 07, 2019 1:31 pm
Forum: Electronegativity
Topic: Trend of Electronegativity
Replies: 22
Views: 165

Re: Trend of Electronegativity

Electronegativity decreases as you move down a group and increases as you move across a period. It increases as you move across a period because the nuclear charge increases as you move right. It decreases as you move down a group because the electrons are increasingly experiencing weaker attraction...
by chrischyu4a
Fri Nov 01, 2019 7:20 pm
Forum: Bond Lengths & Energies
Topic: Lattice Energy
Replies: 9
Views: 59

Re: Lattice Energy

When ions form bonds they release energy. Lattice energy is basically the amount of energy that is released when ions form a compound.
by chrischyu4a
Fri Nov 01, 2019 7:18 pm
Forum: Bond Lengths & Energies
Topic: Bond energies
Replies: 4
Views: 41

Re: Bond energies

In terms of bond energy triple bonds have the largest bond energy while single bonds have the smallest bond energy. Lone pair electrons also repel other lone pair electrons on adjacent atoms which contributes to single bonds having weaker bonds.
by chrischyu4a
Fri Nov 01, 2019 7:14 pm
Forum: Electronegativity
Topic: Polarity
Replies: 5
Views: 48

Re: Polarity

Basically atoms have different electronegativities and the difference in electronegativities between two atoms is what causes a bond to be polar. So yes, they are correlated but they aren't the same.
by chrischyu4a
Fri Nov 01, 2019 7:12 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal charge purpose
Replies: 40
Views: 2091

Re: Formal charge purpose

A formal charge of 0 indicates that the molecule is at its most stable structure.
by chrischyu4a
Fri Nov 01, 2019 7:09 pm
Forum: Ionic & Covalent Bonds
Topic: Midterm
Replies: 28
Views: 237

Re: Midterm

The midterm will include everything including Friday's lecture besides the last slide that was shown.
by chrischyu4a
Fri Oct 25, 2019 6:00 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: 2nd electron
Replies: 4
Views: 40

Re: 2nd electron

Whenever you remove the first electron, you create a cation. So technically, the nuclear charge is greater which is why the second ionization energy is always significantly larger than the first.
by chrischyu4a
Fri Oct 25, 2019 5:56 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Noble Gas Configuration
Replies: 10
Views: 92

Re: Noble Gas Configuration

My TA mentioned how you can use the noble gas configuration whenever you want. You arent required to use the fully written out notation unless inquired to.
by chrischyu4a
Fri Oct 25, 2019 5:05 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: 1E25
Replies: 1
Views: 27

Re: 1E25

Unless they specifically ask you to show the arrangement of electrons in the orbital, you should use the "s2p6d10" notation.
by chrischyu4a
Fri Oct 25, 2019 4:56 pm
Forum: Properties of Light
Topic: Speed of light
Replies: 13
Views: 104

Re: Speed of light

All electromagnetic radiation is light itself which is why they all travel at 3*10^8 m/s. The factors that distinguishes the types of EM waves are frequency and wavelength.
by chrischyu4a
Fri Oct 25, 2019 4:53 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Nodal Planes
Replies: 7
Views: 94

Re: Nodal Planes

a nodal plane is an area where the probability of finding electrons is zero. S orbitals are the only orbitals that have nodal planes considering how the orbital itself is spherical and doesn't intersect the nucleus in any way
by chrischyu4a
Fri Oct 25, 2019 4:48 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: s, p, d, f orbitals
Replies: 15
Views: 136

Re: s, p, d, f orbitals

The 3d orbital should have more energy than 4s since the electrons in the 3d orbital experience heavy repulsion from electron interactions between the other electrons in the 3d and 3p orbitals. As a result, it requires less energy for electrons to occupy the 4s orbital.
by chrischyu4a
Fri Oct 18, 2019 7:09 pm
Forum: Quantum Numbers and The H-Atom
Topic: Nodal Plane
Replies: 4
Views: 52

Re: Nodal Plane

A nodal plane is an area where there is no chance of finding an electron. S orbitals do not have this because they are spherical and don't have any gaps that p,d, and f orbitals possess
by chrischyu4a
Fri Oct 18, 2019 7:03 pm
Forum: Quantum Numbers and The H-Atom
Topic: Spectral Series
Replies: 3
Views: 70

Re: Spectral Series

Considering how the Balmer series is associated with visible light and the Lyman series is associated with UV light, wavelengths in the Balmer series should range from around 400 nm to 740 nm while wavelengths in the Lyman series should range from 10 nm to 400 nm.
by chrischyu4a
Fri Oct 18, 2019 6:59 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Advice for studying
Replies: 58
Views: 969

Re: Advice for studying

One routine that helped me get through chem was to just do as many practice problems as possible and to review the problems that you weren't able to solve initially or struggled with.
by chrischyu4a
Fri Oct 18, 2019 6:56 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Spin State
Replies: 17
Views: 108

Re: Spin State

Do the positive and negative values relate to the arrows he draws in class? I'm confused as to how that relates to the spin state. The positive and negative values don't necessarily correlate to a certain direction such as "up" or "down" that most people refer to, it just convey...
by chrischyu4a
Fri Oct 18, 2019 6:52 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Energy of 4s and 3d
Replies: 1
Views: 31

Re: Energy of 4s and 3d

Basically electrons in the 3d orbital have a lot of repulsion because of the electrons that occupy the 3s and 3p orbitals. Considering how the 4s orbital is further away and experiences less repulsion, it requires less energy for electrons to occupy it than the 3d orbital.
by chrischyu4a
Fri Oct 11, 2019 4:06 pm
Forum: Properties of Light
Topic: Energy Levels
Replies: 8
Views: 136

Re: Energy Levels

It is in the ultraviolet region because the gap between n=1 and n=2 has the greatest gap compared to the other energy which results in the greatest energy release which can be associated to the ultraviolet region.
by chrischyu4a
Fri Oct 11, 2019 3:56 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Decreasing gap between energy level
Replies: 6
Views: 105

Re: Decreasing gap between energy level

Electrons closer to the nucleus are more affected by the pull and thus require more energy to remove. The further the electrons are from the nucleus, the weaker the pull, which results in less energy required to remove electrons.
by chrischyu4a
Fri Oct 11, 2019 3:52 pm
Forum: Trends in The Periodic Table
Topic: Ionization Energy: Na vs. Al
Replies: 3
Views: 78

Re: Ionization Energy: Na vs. Al

Simply put, aluminum has 3 valence electrons while sodium only has 1. It takes more energy for aluminum to lose 3 electrons to complete its octet shell than it does for sodium to lose one electron.
by chrischyu4a
Fri Oct 11, 2019 3:49 pm
Forum: Trends in The Periodic Table
Topic: Electronegativity vs. Electron Affinity?
Replies: 11
Views: 475

Re: Electronegativity vs. Electron Affinity?

Basically electron affinity is the amount of energy that is released when an electron is added to an atom while electronegativity is an atom's ability to attract electrons
by chrischyu4a
Fri Oct 11, 2019 3:28 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Rydberg equation [ENDORSED]
Replies: 73
Views: 2570

Re: Rydberg equation [ENDORSED]

Can someone clarify why the Rydberg equation is always negative? Because you're "losing" energy because it's being transferred somewhere else? The Rydberg equation is negative because it is comparing the energy difference between the two levels the electrons transitioned between. When an ...
by chrischyu4a
Fri Oct 11, 2019 3:27 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Rydberg equation [ENDORSED]
Replies: 73
Views: 2570

Re: Rydberg equation [ENDORSED]

Can someone clarify why the Rydberg equation is always negative? Because you're "losing" energy because it's being transferred somewhere else? The Rydberg equation is negative because it is comparing the energy difference between the two levels the electrons transitioned between. When an ...
by chrischyu4a
Fri Oct 04, 2019 5:01 pm
Forum: SI Units, Unit Conversions
Topic: which unit to use
Replies: 9
Views: 173

Re: which unit to use

Back in high school, I was told to always put your answer in the original units stated in the problem if not given a specific unit to use.
by chrischyu4a
Fri Oct 04, 2019 4:58 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Molar mass vs. Molecular Weight
Replies: 5
Views: 91

Re: Molar mass vs. Molecular Weight

Molecular weight is basically the mass of one molecule. Molar mass would be the mass of a mole of a molecule.
by chrischyu4a
Fri Oct 04, 2019 4:50 pm
Forum: SI Units, Unit Conversions
Topic: Sig figs
Replies: 18
Views: 245

Re: Sig figs

How important is it to know all the rules for sig figs? I feel like I know some basics but not the more specific rules that pertain to addition/subtraction or multiplication/division? Back in high school, I know that sig figs account for a lot of points so I believe that it is important that you fo...
by chrischyu4a
Fri Oct 04, 2019 4:39 pm
Forum: SI Units, Unit Conversions
Topic: Sig Fig Mistakes
Replies: 17
Views: 241

Re: Sig Fig Mistakes

One important thing to note is that when determining the number of sig figs to use in your final answer, you don't consider the amount of sig figs in constants such as Avogadro's number.
by chrischyu4a
Fri Oct 04, 2019 4:36 pm
Forum: SI Units, Unit Conversions
Topic: Question about Showing Work
Replies: 22
Views: 298

Re: Question about Showing Work

My TA mentioned how partial credit is possible to earn so it would be best if you show your work for every problem. When it comes to balancing chemical equations, you can earn partial credit if you write down the oxidation numbers for each compound/element.

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