Search found 50 matches

by Matthew Tsai 3A
Thu Dec 05, 2019 8:56 pm
Forum: Lewis Acids & Bases
Topic: Memorizing Charges of Transition Metals
Replies: 9
Views: 43

Re: Memorizing Charges of Transition Metals

It may be more intuitive to memorize the charges of common ligands (from the chart) and use that combined with net charge of the compound/complex in order to calculate the charge of the transition metal cation.
by Matthew Tsai 3A
Thu Dec 05, 2019 8:54 pm
Forum: Bronsted Acids & Bases
Topic: HF is a weak acid?
Replies: 8
Views: 43

Re: HF is a weak acid?

Due to the smaller size of fluorine, the H-F bond is very strong, preventing much dissociation in water and thus preventing HF from donating a proton.
by Matthew Tsai 3A
Thu Dec 05, 2019 8:53 pm
Forum: Bronsted Acids & Bases
Topic: Difference between bronsted and conjugate
Replies: 2
Views: 7

Re: Difference between bronsted and conjugate

Bronsted acids are proton donors and Bronsted bases are proton acceptors. When an acid donates its proton it becomes the conjugate base and when the base accepts the proton it becomes the conjugate acid.
by Matthew Tsai 3A
Thu Dec 05, 2019 8:48 pm
Forum: Conjugate Acids & Bases
Topic: Double Arrows
Replies: 3
Views: 14

Re: Double Arrows

Not sure if you will be penalized, but it would probably be best to get used to including double arrows for equilibrium reactions.
by Matthew Tsai 3A
Thu Dec 05, 2019 8:47 pm
Forum: Bronsted Acids & Bases
Topic: Bronsted vs. Lewis Definitions
Replies: 2
Views: 17

Re: Bronsted vs. Lewis Definitions

The Lewis definition is just broader, so all Bronsted acids and bases will work as Lewis acids and bases as well. The only difference would be when dealing with compounds that don't have H+, in which case it would only work as a Lewis acid/base.
by Matthew Tsai 3A
Sat Nov 30, 2019 8:45 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: coordination number
Replies: 8
Views: 27

Re: coordination number

Coordination number just refers to the total number of bound ligands in the coordination sphere.
by Matthew Tsai 3A
Sat Nov 30, 2019 8:44 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Ligands
Replies: 3
Views: 18

Re: Ligands

A ligand must have a lone pair; otherwise it would be unable to bind to the central cation and form a coordination complex.
by Matthew Tsai 3A
Sat Nov 30, 2019 8:43 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Polydentate
Replies: 3
Views: 19

Re: Polydentate

A ligand is polydentate if it has multiple sites at which it can bind to a cation. The shape would look similar to an incomplete ring(s) with lone pairs at the ends.
by Matthew Tsai 3A
Sat Nov 30, 2019 8:41 pm
Forum: Amphoteric Compounds
Topic: compounds
Replies: 5
Views: 19

Re: compounds

Any compound is considered amphoteric if it acts as both an acid and a base, in other words it can either donate a proton or accept one (e.g. H2O)
by Matthew Tsai 3A
Sat Nov 30, 2019 8:33 pm
Forum: Lewis Acids & Bases
Topic: acid v. base?
Replies: 16
Views: 52

Re: acid v. base?

Lewis bases should have a lone pair to donate while lewis acids are usually positively charged and therefore able to accept an electron pair.
by Matthew Tsai 3A
Sun Nov 24, 2019 11:46 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bent vs linear
Replies: 56
Views: 184

Re: Bent vs linear

If there are either one or two electron pairs on the central atom along with the two bonded atoms, it would result in bent shape. Otherwise, the molecule would be linear in shape.
by Matthew Tsai 3A
Sun Nov 24, 2019 11:44 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angles
Replies: 7
Views: 25

Re: Bond Angles

When the central atom has one or more lone pairs, the higher strength of electron pair-electron pair and electron pair-bonded pair repulsion compared to bonded pair-bonded pair repulsion results in the bonds being pushed to form smaller angles.
by Matthew Tsai 3A
Sun Nov 24, 2019 11:42 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: AXE Format
Replies: 34
Views: 96

Re: AXE Format

I think it would be okay to just put AXE and the 1s would be redundant.
by Matthew Tsai 3A
Sun Nov 24, 2019 11:41 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Hydrogen Bonding
Replies: 13
Views: 47

Re: Hydrogen Bonding

Yes, generally with the conditions necessary for hydrogen bonding to occur, which is hydrogen bonded to a very electronegative atom (F, O, or N), the resulting molecule would be polar.
by Matthew Tsai 3A
Sun Nov 24, 2019 11:40 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: T-shape
Replies: 21
Views: 52

Re: T-shape

You would get a T-shape with the formula AX3E2, so three bonded atoms (two along the y-axis) and one approximately perpendicular to them with two lone pairs.
by Matthew Tsai 3A
Tue Nov 12, 2019 9:37 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: Induced dipole vs dipole
Replies: 3
Views: 20

Re: Induced dipole vs dipole

An induced dipole refers to when a polar molecule induces a dipole moment in a nonpolar molecule when they are near each other. For example, if the nonpolar molecule is near a positive dipole of a polar molecule, its electrons would be attracted towards it, forming a negative dipole. While the nonpo...
by Matthew Tsai 3A
Tue Nov 12, 2019 9:29 pm
Forum: Electronegativity
Topic: dipole moments
Replies: 7
Views: 20

Re: dipole moments

If you visualize the electron cloud surrounding a molecule, it would make sense that the more electronegative atom(s) would pull the shared electrons closer to itself, forming a negative dipole moment on that region of the molecule and a positive dipole moment on the opposite end.
by Matthew Tsai 3A
Tue Nov 12, 2019 9:27 pm
Forum: Bond Lengths & Energies
Topic: Van Der Waals BP
Replies: 6
Views: 29

Re: Van Der Waals BP

Forces that affect boiling point are based on the strength of the intermolecular forces, so the ones that would most affect BP are the ones that are the strongest. So ionic interactions would have the highest effect, followed by hydrogen bonding, then ion-dipole interactions, and the last few all b...
by Matthew Tsai 3A
Tue Nov 12, 2019 9:19 pm
Forum: Dipole Moments
Topic: Strength of Interactions
Replies: 4
Views: 28

Re: Strength of Interactions

I believe h-bonding is the strongest type of intermolecular force that can exist in covalent molecules as it is the strongest dipole-dipole interaction. But in general, ion-ion attraction is the strongest intermolecular force due to the large charge difference that exists between atoms.
by Matthew Tsai 3A
Tue Nov 12, 2019 9:13 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR model
Replies: 4
Views: 33

Re: VSEPR model

VSEPR stands for Valence Shell Electron Pair Repulsion, and VSEPR theory refers to the concept that molecular shape can be determined (at least for smaller molecules) based on the number of bonded atoms and lone pairs due to their tendency to maximize distance from each other. The AXE formula just i...
by Matthew Tsai 3A
Sun Nov 10, 2019 4:53 pm
Forum: Bond Lengths & Energies
Topic: Strongest Bond
Replies: 15
Views: 59

Re: Strongest Bond

For intermolecular forces:
LDF/Van der Waals < dipole-dipole < h-bonds (the strongest type of dipole-dipole attraction)
by Matthew Tsai 3A
Sun Nov 10, 2019 4:41 pm
Forum: Dipole Moments
Topic: Polarity
Replies: 8
Views: 28

Re: Polarity

Generally, if there is a particular part of the molecule that is more electronegative and the shape of the molecule does not allow for the charges to cancel (e.g. if the structure is not symmetrical), then the molecule is polar.
by Matthew Tsai 3A
Sun Nov 10, 2019 4:39 pm
Forum: Coordinate Covalent Bonds
Topic: Coordinate Covalent Bond
Replies: 8
Views: 36

Re: Coordinate Covalent Bond

Simply put, a coordinate covalent bond occurs when one atom provides both electrons used in the bond, as opposed to one electron from each atom in a normal covalent bond.
by Matthew Tsai 3A
Sun Nov 10, 2019 4:37 pm
Forum: Resonance Structures
Topic: Resonance Structures
Replies: 3
Views: 25

Re: Resonance Structures

The common exceptions of atoms that do not require at least a full octet are the first four elements, along with boron and aluminum. Otherwise, there aren't really any naturally occurring examples of an element that doesn't fill its octet so any resonance structures that break the rule wouldn't be v...
by Matthew Tsai 3A
Sun Nov 10, 2019 4:34 pm
Forum: Ionic & Covalent Bonds
Topic: polarizing power
Replies: 7
Views: 30

Re: polarizing power

Yes; because these elements are located in the second period, they do not have access to the empty 3d orbital and cannot hold an expanded octet.
by Matthew Tsai 3A
Sat Nov 02, 2019 3:25 pm
Forum: DeBroglie Equation
Topic: Converting mass to kilograms for de broglie
Replies: 7
Views: 28

Re: Converting mass to kilograms for de broglie

Yes, you would need to convert to kilograms because Planck's constant, h, uses kilograms.
by Matthew Tsai 3A
Sat Nov 02, 2019 3:23 pm
Forum: Quantum Numbers and The H-Atom
Topic: determining the number of orbitals
Replies: 7
Views: 55

Re: determining the number of orbitals

The quantum number that you would want to use to determine the number of orbitals in a given subshell would be l, which identifies the actual subshell: s (l=0), p (l=1), d (l=2), or f (l=3). They have 1, 3, 5, and 7 orbitals respectively.
by Matthew Tsai 3A
Sat Nov 02, 2019 3:20 pm
Forum: Photoelectric Effect
Topic: Ionization Energy vs Threshold Energy
Replies: 4
Views: 30

Re: Ionization Energy vs Threshold Energy

Threshold energy (represented by the work function) is relevant to the photoelectric effect because it refers to the energy required to remove a single electron from a certain metal surface. On the other hand, ionization energy is defined as the energy required to remove an electron from an atom in ...
by Matthew Tsai 3A
Sat Nov 02, 2019 3:17 pm
Forum: Coordinate Covalent Bonds
Topic: Difference between coordinate covalent and covalent bond
Replies: 6
Views: 556

Re: Difference between coordinate covalent and covalent bond

In a coordinate covalent bond, one atom provides both of the bonding valence electrons.
by Matthew Tsai 3A
Sat Nov 02, 2019 3:10 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: What are the octet exceptions?
Replies: 11
Views: 61

Re: What are the octet exceptions?

Elements beyond the third row of the periodic table are able to hold extra valence electrons beyond the octet because they have an unfilled d-orbital.
by Matthew Tsai 3A
Sun Oct 27, 2019 6:20 pm
Forum: Resonance Structures
Topic: Resonance
Replies: 8
Views: 34

Re: Resonance

Resonance just refers to the concept that a single molecule is not restricted to a rigid structure. Rather, it can change into unique resonance structures.
by Matthew Tsai 3A
Sun Oct 27, 2019 6:19 pm
Forum: Lewis Structures
Topic: Lone pair
Replies: 8
Views: 34

Re: Lone pair

Yep, as previous answers stated, lone pairs just refer to a pair of electrons in an orbital that are not shared with another atom.
by Matthew Tsai 3A
Sun Oct 27, 2019 6:17 pm
Forum: Ionic & Covalent Bonds
Topic: Covalent Bonds
Replies: 11
Views: 70

Re: Covalent Bonds

Yes, covalent bonds can only be formed between two nonmetals.
by Matthew Tsai 3A
Sun Oct 27, 2019 6:15 pm
Forum: Ionic & Covalent Bonds
Topic: Valence Electrons
Replies: 16
Views: 100

Re: Valence Electrons

For the s and p block elements, the number of valence electrons is just the group number, but it can vary for the d block based on electron configuration. Charged ions may also carry extra or fewer valence electrons.
by Matthew Tsai 3A
Sun Oct 27, 2019 6:13 pm
Forum: Sigma & Pi Bonds
Topic: Single vs. Double bonds
Replies: 15
Views: 76

Re: Single vs. Double bonds

Because there are more electrons being shared between the atoms, there is a greater attractive force that pulls the atoms closer together, shortening bond length.
by Matthew Tsai 3A
Fri Oct 18, 2019 4:52 pm
Forum: Quantum Numbers and The H-Atom
Topic: Nodal Plane
Replies: 4
Views: 27

Re: Nodal Plane

A nodal plane is just a planar area in which electrons cannot be located. Due to the spherical shape of the s-orbital, it does not have any.
by Matthew Tsai 3A
Fri Oct 18, 2019 4:51 pm
Forum: Properties of Electrons
Topic: effective nuclear charge
Replies: 5
Views: 25

Re: effective nuclear charge

I don't think we will be expected to calculate a specific value for effective nuclear charge, but to conceptually understand it, effective nuclear charge can be used to determine which energy state an electron is in due to the shielding effect.
by Matthew Tsai 3A
Fri Oct 18, 2019 4:46 pm
Forum: Properties of Light
Topic: Equations and Constants
Replies: 6
Views: 41

Equations and Constants

Are there any specific equations or constants that aren't provided on the formula sheet but will be included on tests?
by Matthew Tsai 3A
Fri Oct 18, 2019 4:43 pm
Forum: Photoelectric Effect
Topic: Intensity v Frequency
Replies: 5
Views: 31

Re: Intensity v Frequency

Intensity is determined by amplitude of a wave while frequency is determined by the length (specifically how short) a wave is. In the famous photoelectric effect experiment, it was determined that the energy of light is proportional to frequency, rather than the expected which was amplitude/intensit...
by Matthew Tsai 3A
Fri Oct 18, 2019 4:39 pm
Forum: Properties of Electrons
Topic: Momentum
Replies: 11
Views: 43

Re: Momentum

Like previous answers mentioned, momentum is mass * velocity. So, if an object is moving at a slow velocity but has a large mass, it can still have a substantial momentum.
by Matthew Tsai 3A
Wed Oct 09, 2019 6:29 pm
Forum: Molarity, Solutions, Dilutions
Topic: Symbols for Molarity
Replies: 8
Views: 106

Re: Symbols for Molarity

Yes, as previous answers mentioned, they refer to the same thing. I believe "c" is used in general reference to some concentration while "M" is a more specific reference to molarity, which is a specific measure defined as mol/L.
by Matthew Tsai 3A
Wed Oct 09, 2019 6:27 pm
Forum: Significant Figures
Topic: %Mass Composition
Replies: 12
Views: 82

Re: %Mass Composition

The same rules for significant figures should still apply, and generally that would be anywhere from 4-5 sig figs based on what's given in the problem.
by Matthew Tsai 3A
Wed Oct 09, 2019 6:24 pm
Forum: Balancing Chemical Reactions
Topic: Fractions
Replies: 20
Views: 130

Re: Fractions

It's generally good practice to convert all the coefficients to integers, as that gives the most accurate representation of the chemical reaction.
by Matthew Tsai 3A
Wed Oct 09, 2019 6:06 pm
Forum: Molarity, Solutions, Dilutions
Topic: Polyatomic ions on Test 1
Replies: 4
Views: 59

Re: Polyatomic ions on Test 1

For the first test, it won't be required to have the names and formulas of polyatomic ions memorized, but I believe they will not always be provided in future tests.
by Matthew Tsai 3A
Wed Oct 09, 2019 6:04 pm
Forum: SI Units, Unit Conversions
Topic: SI Units
Replies: 2
Views: 50

Re: SI Units

One angstrom is 10^-10 meters (m), or 100 picometers (pm).
by Matthew Tsai 3A
Thu Oct 03, 2019 4:53 pm
Forum: Molarity, Solutions, Dilutions
Topic: Molarity
Replies: 9
Views: 67

Re: Molarity

Molarity is relevant when dealing with solutions. By doing molarity calculations, you can determine the moles of solute and how you may need to dilute the solution.
by Matthew Tsai 3A
Thu Oct 03, 2019 4:21 pm
Forum: Molarity, Solutions, Dilutions
Topic: Molality vs Molarity
Replies: 2
Views: 30

Re: Molality vs Molarity

Both are generally used to refer to solution concentration. Molarity, as we know, is calculated as moles of solute/L of solvent. Meanwhile, molality is moles solute/kg solvent. I think most of the time though, molarity is the preferred measurement to use.
by Matthew Tsai 3A
Thu Oct 03, 2019 4:19 pm
Forum: Molarity, Solutions, Dilutions
Topic: Molar Mass Clarification
Replies: 3
Views: 27

Re: Molar Mass Clarification

Molar mass refers to the mass in grams of one mole of a certain particle. For atoms, the molar mass is indicated on the periodic table (same as atomic mass). For molecules, just add up the molar masses of all its constituents.
by Matthew Tsai 3A
Thu Oct 03, 2019 4:14 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Avogadro's Number?
Replies: 16
Views: 142

Re: Avogadro's Number?

As the previous answers mentioned, it's just a specific name for the number 6.022 x 10^23. Generally you would just think of it as a mole.
by Matthew Tsai 3A
Wed Oct 02, 2019 7:31 pm
Forum: SI Units, Unit Conversions
Topic: Units
Replies: 5
Views: 78

Re: Units

For the purposes of chemistry, I think it's probably good to know prefixes like milli, micro, nano, pico, etc. because they are used more frequently, for example in stoichiometry, rather than ones that indicate greater magnitude (mega, giga, etc.)

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