## Search found 31 matches

Sat Dec 08, 2018 9:26 pm
Forum: Calculating the pH of Salt Solutions
Topic: calculating pH
Replies: 4
Views: 295

### Re: calculating pH

That's right. When calculating pH, it will only be dealing with strong acids and/or strong bases. However, weak acids and bases will be on the final but we will only be ranking their relative strengths.
Sat Dec 08, 2018 9:25 pm
Forum: Quantum Numbers and The H-Atom
Topic: Why is this statement incorrect?
Replies: 3
Views: 346

### Re: Why is this statement incorrect?

The quantum number is n=9. Then after is l, the subshell, and l = 0 through 8, remember that l = 0 through n-1. The question asks for magnetic quantum number ml which is -l through l, so it is -8 through 8, so the lowest value it can take is -8, not -9 (because l is 0 through 8).
Sat Dec 08, 2018 9:19 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: ranking strong bases
Replies: 2
Views: 81

### Re: ranking strong bases

The trends you look at for ranking strong bases are the same as strong acids, which are the strength of the bonds and the stability of the resulting conjugate.
Sat Dec 08, 2018 9:18 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: polarizability/polarizing power test 3
Replies: 3
Views: 383

### Re: polarizability/polarizing power test 3

Polarizable: O^2-, N^3-, Cl-, At-
Polarizing power: Rb+, Sr^2+, Na+, Be^2+
Sat Dec 01, 2018 11:11 pm
Forum: Dipole Moments
Topic: Dipole moments and resonances
Replies: 3
Views: 193

### Re: Dipole moments and resonances

If a molecule does have dipole moments I'm not sure resonance would necessarily cancel out the dipole moments. This is because a molecule's dipole moments are due to the electrons being closer to one atom than the other in one specific bond of the molecule. Resonance distributes the electron density...
Sat Dec 01, 2018 10:57 pm
Forum: Naming
Topic: Charge
Replies: 1
Views: 66

### Re: Charge

You would have to memorize the charges and they are listed on this link
https://lavelle.chem.ucla.edu/wp-conten ... pounds.pdf
Sat Dec 01, 2018 10:49 pm
Forum: Lewis Acids & Bases
Topic: Strength of Acids
Replies: 3
Views: 142

### Re: Strength of Acids

Another way you can identify the strength of acids is that acidity increases with electronegativity and also increases with atomic radii.
Sat Nov 24, 2018 6:20 pm
Forum: Dipole Moments
Topic: Dipole Moment
Replies: 2
Views: 149

### Re: Dipole Moment

The greatest dipole moment will come from the two atoms having the greatest difference in electronegativity which translates to the elements being furthest away from each other on the periodic table. So the smallest dipole moment will be the atoms with the smallest difference in electronegativity.
Sat Nov 24, 2018 6:12 pm
Forum: Octet Exceptions
Topic: Incomplete Octet
Replies: 2
Views: 361

### Re: Incomplete Octet

I would think that bonding wise, the molecule will bond more easily because the incomplete octet would make the molecule "more eager" to bond to complete the octet and become stable.
Sat Nov 24, 2018 6:09 pm
Forum: Electronegativity
Topic: Determine Electronegativity of Molecule
Replies: 1
Views: 111

### Re: Determine Electronegativity of Molecule

I would think that the more electronegative molecule is the one that has the more electronegative element, in your example it would be HF. So I would use the periodic table trend for electronegativity as reference.
Sat Nov 17, 2018 11:54 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Determining Shape
Replies: 10
Views: 415

### Re: Determining Shape

You will always need to draw the lewis structure because a compound can have numerous structures drawn and you need to find the one with the lowest energy to be able to find the correct shape as well as the reason mentioned above.
Sat Nov 17, 2018 11:46 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angles
Replies: 16
Views: 410

### Re: Bond Angles

You'll need to memorize the angles, but not how to draw them.
Sat Nov 17, 2018 11:46 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular shape vs electron geometry
Replies: 4
Views: 138

### Re: Molecular shape vs electron geometry

Another thing to note is that sometimes the two will be the same, and sometimes they will have different shapes.
Sat Nov 10, 2018 7:31 pm
Forum: Trends in The Periodic Table
Topic: Electron Affinity
Replies: 1
Views: 360

### Re: Electron Affinity

A negative in front of the energy calculated only means that the energy you calculated is less relative to the "original" energy. This is why released energy has a negative sign. However, since electron affinity already means that energy is released, having a negative sign in front of the ...
Sat Nov 10, 2018 7:18 pm
Forum: Electronegativity
Topic: Electronegativity
Replies: 3
Views: 156

### Re: Electronegativity

The trends of the two in the periodic table are the same, but ionization energy is the energy required to remove the outer most electron in a gaseous state. Electronegativity is the tendency of an atom to gain an electron. The two are very similar but one important thing to note is that nitrogen has...
Sat Nov 10, 2018 7:11 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polarizability Trend
Replies: 6
Views: 1170

### Re: Polarizability Trend

The more electrons, the less control the nuclear charge has on electron (and therefore charge) distribution, which increases polarizability of the atom. Therefore, I would think that anions (since the atom gains an electron) has greater polarizability and cations (which lose electrons) have less pol...
Sun Nov 04, 2018 1:11 am
Forum: Octet Exceptions
Topic: Octet Rule
Replies: 2
Views: 135

### Re: Octet Rule

The octet rule is basically that atoms share/transfer e- until a noble gas configuration is reached, but there are exceptions to that rule.
Sun Nov 04, 2018 1:09 am
Forum: Octet Exceptions
Topic: Octet
Replies: 6
Views: 283

### Re: Octet

There are elements with expanded valence shells (such as P, S, and Cl) that can accommodate more than 8 valence e- since atoms in period 3 or higher have d-orbitals in valence shell that accommodate additional e-. Another exception are radicals, which are compounds with unpaired e-. An example is CH...
Sun Nov 04, 2018 1:00 am
Forum: Formal Charge and Oxidation Numbers
Topic: Importance of Oxidation Numbers
Replies: 1
Views: 300

### Re: Importance of Oxidation Numbers

For formal charge in Lewis Structures, all you need to know is the number of shared and lone electrons in the structure. Keep in mind that the formula is FC = V - (L + S/2), so oxidation numbers are not involved for formal charge.
Fri Oct 26, 2018 11:48 pm
Forum: Ionic & Covalent Bonds
Topic: Homework 2B.21
Replies: 3
Views: 146

### Re: Homework 2B.21

You can write two Lewis structures by changing which atom is the central atom, so one structure will have Cl as the central atom, and the other structure will have O as the central atom. The most likely structure will be the one where the atom with lowest ionization energy is the central atom.
Fri Oct 26, 2018 11:43 pm
Forum: Lewis Structures
Topic: Drawing Lewis Structures with Charges
Replies: 6
Views: 321

### Re: Drawing Lewis Structures with Charges

For cations, remove 1 e- for each +1 charge. For anions, add 1 e- for each -1 charge.
Fri Oct 26, 2018 11:40 pm
Forum: Trends in The Periodic Table
Replies: 8
Views: 293

Information like this will be given, you don't need to memorize them.
Sat Oct 20, 2018 12:20 am
Forum: Quantum Numbers and The H-Atom
Topic: Energy levels
Replies: 1
Views: 124

### Re: Energy levels

This is basically asking you to do what Professor Dr. Lavelle did in lecture, where we knew one of the values of the quantum numbers and, using the relationships between those numbers (for example, l = 0, 1, 2, …, n-1 ), found the rest of the quantum numbers.
Sat Oct 20, 2018 12:16 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Electrostatic potential energy
Replies: 1
Views: 67

### Re: Electrostatic potential energy

One thing is that the equation reflects the inverse relationship between E (electrostatic potential energy) and r (distance between charges). This relationship demonstrates how the inner e- shield outer e- from the electrostatic attraction of the positive nucleus ∴ outer e- feel a reduced electrosta...
Sat Oct 20, 2018 12:08 am
Forum: DeBroglie Equation
Topic: Wave properties of large particles
Replies: 3
Views: 137

### Re: Wave properties of large particles

I took it as large particles like baseballs and everyday objects don't move like waves, but give off small undetectable amounts of wave energy.
Fri Oct 12, 2018 2:54 pm
Forum: DeBroglie Equation
Topic: De Brogile wavelengths
Replies: 1
Views: 62

### Re: De Brogile wavelengths

We can measure the wavelike properties of particles but not for everyday objects because the mass is too big. That is why the equation works best for small particles like electrons, because we will have to divide by the object's mass. In the example with the car we calculated it's wavelength to be 1...
Fri Oct 12, 2018 2:50 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Wavelength Worked Example from Lecture
Replies: 3
Views: 46

### Re: Wavelength Worked Example from Lecture

1.64 x 10^-38m is an EXTREMELY small wavelength. This would require very advanced and sensitive technology to detect such a small wavelength, but to measure something like that is currently impossible. We can measure small wavelengths but anything 10^-38 is so minute and indistinguishable we are una...
Fri Oct 12, 2018 2:47 pm
Forum: DeBroglie Equation
Topic: "Wavelength" of everything with mass
Replies: 3
Views: 73

### Re: "Wavelength" of everything with mass

So the De Broglie Equation: λ = h / (mass x velocity) states that any moving particle with momentum, p, has wavelike properties with wavelength λ. I think a baseball can give off wavelengths because all matter is made up of particles, so if the object is moving the particles making it up are moving,...
Sat Oct 06, 2018 2:19 pm
Forum: Properties of Electrons
Topic: Light and Electrons
Replies: 1
Views: 98

### Re: Light and Electrons

I think the position ie the shells/orbitals of the electrons are significant in how electrons are affected by light because the electrons in the outermost shells have the highest energy, therefore less outside energy is required to affect it. Following this trend, electrons in the inner shells are a...
Sat Oct 06, 2018 2:02 pm
Forum: Limiting Reactant Calculations
Topic: Calculating the amount of moles
Replies: 3
Views: 219

### Re: Calculating the amount of moles

To start, convert the 1kg of CaCO3(s) to grams then moles (by dividing its weight by its molar mass). This question is essentially a "If you have this much of this reactant, how much of this product will be produced?" So basically convert the given amount of the reactant to moles by dividi...
Fri Oct 05, 2018 11:01 am
Forum: Limiting Reactant Calculations
Topic: Compensating for Mole Ratios in Limiting Reactants
Replies: 3
Views: 158

### Re: Compensating for Mole Ratios in Limiting Reactants

To determine which of the two is the limiting reactant, you need to use the molar ratio. In the balanced equation, you need 4 moles of NH3 to completely react with 5 moles of O2. You need to simplify this ratio so that one of the two reactants is set to one, but it does not matter which. So if we de...