Search found 51 matches

by Cynthia Rodas 4H
Sun Dec 08, 2019 5:34 pm
Forum: Dipole Moments
Topic: dipole dipole
Replies: 3
Views: 22

Re: dipole dipole

Hydrogen bonds are stronger than dipole-dipole. The strength for intermolecular forces arranged from lowest to highest is London forces, dipole-dipole, H-bonding, and ion-dipole.
by Cynthia Rodas 4H
Sun Dec 08, 2019 5:30 pm
Forum: Naming
Topic: Cation vs. Anion Transition Metal
Replies: 3
Views: 28

Re: Cation vs. Anion Transition Metal

The suffix -ate is added to the metal when the complex is anionic. So if the overall charge of the complex is negative like it was in Part C, the name of cobalt became cobaltate.
by Cynthia Rodas 4H
Sun Dec 08, 2019 5:15 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: oxidation number
Replies: 3
Views: 25

Re: oxidation number

The elements outside of the bracket affect the oxidation number because in order for the coordination compound to be neutral, the charges of the elements within the bracket and outside of the bracket must cancel each other out.
by Cynthia Rodas 4H
Sun Dec 08, 2019 5:07 pm
Forum: Naming
Topic: NH4[PtCl3(NH3)]
Replies: 5
Views: 37

Re: NH4[PtCl3(NH3)]

Whenever a complex is anionic, meaning that it has an overall negative charge, the ending of the metal will be -ate.
by Cynthia Rodas 4H
Sun Dec 08, 2019 4:56 pm
Forum: Naming
Topic: bis- tris- tetrakis-
Replies: 8
Views: 67

Re: bis- tris- tetrakis-

The prefixes -bis, -tris, and -tetrakis are added when the ligand already has a Greek prefix or if the complex is polydentate.
by Cynthia Rodas 4H
Sun Dec 01, 2019 10:56 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Ligands
Replies: 4
Views: 32

Re: Ligands

A chelating ligand is when a ligand has more than one bond with the metal atom.
by Cynthia Rodas 4H
Sun Dec 01, 2019 10:41 pm
Forum: Lewis Acids & Bases
Topic: lewis vs. bronsted
Replies: 10
Views: 57

Re: lewis vs. bronsted

Lewis acids are electron acceptors and Bronsted acids are proton donors. Lewis bases are electron donors and Bronsted bases are proton acceptors.
by Cynthia Rodas 4H
Sun Dec 01, 2019 10:30 pm
Forum: Lewis Acids & Bases
Topic: 6A.13
Replies: 1
Views: 20

Re: 6A.13

BF3 is a Lewis acid because Boron has an empty p-orbital. This means that it can accept an electron pair, which by definition is a Lewis acid. The new bond would be formed with the Boron.
by Cynthia Rodas 4H
Sun Dec 01, 2019 10:16 pm
Forum: Bronsted Acids & Bases
Topic: Final
Replies: 13
Views: 81

Re: Final

As far as I know, the Final will be cumulative. However, there will be more of an emphasis on the topics after the midterm. Just make sure you know how to do everything mentioned on the outlines.
by Cynthia Rodas 4H
Sun Dec 01, 2019 7:22 pm
Forum: Naming
Topic: Roman Numeral
Replies: 13
Views: 65

Re: Roman Numeral

Debora Fernandez Clemente_ 4H wrote:How do you calculate the oxidation number of the metal in a complex?


To calculate the oxidation number of the metal in a complex, you would use the equation:

(# metal atoms)(oxidation number of the metal)+(# each ligand)(charge of each ligand)= charge of ion
by Cynthia Rodas 4H
Mon Nov 25, 2019 7:04 am
Forum: Ionic & Covalent Bonds
Topic: ligands
Replies: 5
Views: 61

Re: ligands

Ligands are Lewise bases (electron donors) that are attracted to the central atom since it is a Lewis acid and transition metal. So the ligand can be either an ion or compound.
by Cynthia Rodas 4H
Mon Nov 25, 2019 6:56 am
Forum: Dipole Moments
Topic: Melting points
Replies: 15
Views: 101

Re: Melting points

Melting points are determined based on their intermolecular forces. The more intermolecular forces it has, the more energy it would take to break bonds, resulting in a higher boiling and melting point.
by Cynthia Rodas 4H
Mon Nov 25, 2019 6:53 am
Forum: Sigma & Pi Bonds
Topic: Molecular Shape
Replies: 11
Views: 57

Re: Molecular Shape

Technically, sigma and pi bonds do affect bond length and bond angles. However, the change is minimal so it therefore doesn't have much influence on the molecular shape. Furthermore, the VSEPR model counts single, double, and triple bonds as one region.
by Cynthia Rodas 4H
Mon Nov 25, 2019 6:45 am
Forum: Sigma & Pi Bonds
Topic: sigma and pi bonds
Replies: 19
Views: 108

Re: sigma and pi bonds

Single bonds are all sigma bonds.
Double bonds are all sigma and pi bonds.
Triple bonds are all sigma and 2 pi bonds.
by Cynthia Rodas 4H
Mon Nov 25, 2019 6:40 am
Forum: Electronegativity
Topic: Electronegativity
Replies: 12
Views: 74

Re: Electronegativity

Electronegativity is basically how much an atom attracts electrons. So if there is a high electronegativity difference, it means that there is a strong bond and that the bond length will be shorter.
by Cynthia Rodas 4H
Sun Nov 17, 2019 10:18 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: bond angles
Replies: 8
Views: 35

Re: bond angles

Bond angles get smaller with more lone pairs at the central atom due to lone pair repulsion. Lone pairs want to be far away from the other elements so it will repel the other bonds away from it, causing a decrease in bond angle.
by Cynthia Rodas 4H
Sun Nov 17, 2019 10:04 pm
Forum: Electronegativity
Topic: 2D.3
Replies: 3
Views: 36

Re: 2D.3

The periodic trend for electronegativity is that electronegativity decreases as you go down the periodic table and electronegativity increases as you go from left to right of the periodic table (excluding noble gases). With that being said, although Ba and Be are the same distance from Br in terms o...
by Cynthia Rodas 4H
Sun Nov 17, 2019 9:52 pm
Forum: Octet Exceptions
Topic: Octet expansion
Replies: 6
Views: 53

Re: Octet expansion

An expanded octet can occur if the atomic number of the central atom is 11 or more. This is because elements of the third principal energy level and above have a d-oribital that it can fill.
by Cynthia Rodas 4H
Sun Nov 17, 2019 9:37 pm
Forum: Lewis Structures
Topic: Balanced Lewis Structures
Replies: 6
Views: 36

Re: Balanced Lewis Structures

You would use formal charges to determine which way to write a Lewis structure that is most stable. However, Lewis structures are 2-D and only portray which atoms are bonded together rather than in which position (such as horizontally or vertically). In order to determine it's molecular shape, you w...
by Cynthia Rodas 4H
Sun Nov 17, 2019 9:26 pm
Forum: Bronsted Acids & Bases
Topic: Test2
Replies: 7
Views: 56

Re: Test2

My TA said that Test 2 would consist of all the material we covered after Topic 2D. In regards of memorizing, I would highly recommend memorizing the different molecular shapes and bond angles since I highly doubt that they would provide us with that kind of information.
by Cynthia Rodas 4H
Sun Nov 10, 2019 8:32 pm
Forum: Electronegativity
Topic: Electron Affinity and Electronegativity
Replies: 7
Views: 25

Re: Electron Affinity and Electronegativity

Electron affinity refers to the amount of energy released when an electron is added to an atom. Electronegativity, on the other hand, refers to how much an atom attracts electrons. So an easier way to think of it is electron affinity is how much they want electrons whereas electronegativity is how m...
by Cynthia Rodas 4H
Sun Nov 10, 2019 8:25 pm
Forum: Electronegativity
Topic: definitions
Replies: 8
Views: 60

Re: definitions

Ionization energy refers to the minimum amount of energy needed to remove an electron whereas electron affinity is the amount of energy released when an electron is added.
by Cynthia Rodas 4H
Sun Nov 10, 2019 8:05 pm
Forum: Lewis Structures
Topic: Lewis acids and bases?
Replies: 7
Views: 38

Re: Lewis acids and bases?

Are the cations usually Lewis acids and the anions usually Lewis bases? Yes! So Lewis acids are electron pair acceptors and Lewis bases are electron pair donors. Ions with a positive charge signifiy that it can accept a pair of nonbonding electrons. Ions with a negative charge signify that it can d...
by Cynthia Rodas 4H
Sun Nov 10, 2019 7:51 pm
Forum: Lewis Structures
Topic: Midterm grades
Replies: 26
Views: 246

Re: Midterm grades

My TA said that we would be getting our midterm grades by Wednesday on 11/13.
by Cynthia Rodas 4H
Sun Nov 10, 2019 7:47 pm
Forum: Ionic & Covalent Bonds
Topic: Both types of bonds
Replies: 6
Views: 26

Re: Both types of bonds

It is possible, however the differentiating factor between the two types of bonds comes down to their physical and chemical properties. For example, covalent bonds are typically between two nonmetals whereas ionic bonds are typically between a metal and a nonmetal. You could also observe their diffe...
by Cynthia Rodas 4H
Sun Nov 03, 2019 9:32 pm
Forum: Ionic & Covalent Bonds
Topic: Ionic vs Covalent
Replies: 14
Views: 104

Re: Ionic vs Covalent

Ionic bonds are usually between a metal and a nonmetal. Covalent bonds, on the otherhand, are typically between two nonmetals. Another way to differentiate is by looking at the electronegativity difference. If the electronegativity difference is greater than 2, then it is an ionic bond. If the elect...
by Cynthia Rodas 4H
Sun Nov 03, 2019 9:20 pm
Forum: Properties of Light
Topic: Focus 1.3
Replies: 2
Views: 30

Re: Focus 1.3

In order to find the amount of power produced in watts, you would use the equation: E = \frac{hc}{\lambda } This equation is used to help you find the energy per photon. From here, you would plug in Planck's constant (6.62608 x 10-34 J.s), the speed of light (2.998 x 108 m/s), and the given waveleng...
by Cynthia Rodas 4H
Sun Nov 03, 2019 9:08 pm
Forum: Properties of Light
Topic: HW #1.7
Replies: 5
Views: 366

Re: HW #1.7

Part a: So in order to convert the answer from meters to nanometers, you would try to cancel out the meters in order to get nm by itself. For example: (4.22 * 10^{-7} m) * (\frac{1 nm}{10^{-9} m}) This would leave the result as 422 nm. Part b: This follows the same concept as Part a,...
by Cynthia Rodas 4H
Sun Nov 03, 2019 8:45 pm
Forum: Properties of Light
Topic: 1A.15
Replies: 3
Views: 61

Re: 1A.15

Yes! Great start so far. From here, you would try to get \frac{1}{n_{2}^{2}} by itself by moving all other values to the other side to get: \frac{-2.922 * 10^{15}}{3.29 * 10^{15}} + 1 = \frac{1}{n_{2}^{2}} From here, you would solve the left side which is approximately: 0.11185 = \frac{1}{n_{2}^{2}}...
by Cynthia Rodas 4H
Sun Nov 03, 2019 8:34 pm
Forum: *Black Body Radiation
Topic: Info for Midterm
Replies: 7
Views: 114

Re: Info for Midterm

I don't believe this concept will be on the test. Just focus on the learning objectives that Lavelle listed in each outline. After looking at the last test, I'm pretty sure he would test us on problems that are similar to the homework problems.
by Cynthia Rodas 4H
Sun Oct 27, 2019 9:28 pm
Forum: Ionic & Covalent Bonds
Topic: Ionic VS. Covalent Bond
Replies: 8
Views: 33

Re: Ionic VS. Covalent Bond

Ionic bonds consist of ions in a ratio that result in electrical neutrality. They consist of a metal (cation) and a nonmetal (anion). Metals are cations since they give electrons, whereas nonmetals are anions because they gain electrons. On the other hand, covalent bonds consist of electrically neut...
by Cynthia Rodas 4H
Sun Oct 27, 2019 9:06 pm
Forum: Einstein Equation
Topic: Total Energy of Light
Replies: 2
Views: 42

Re: Total Energy of Light

To calculate the energy of a photon, you would use E = hv. However, some problems might require you to use E = hc/lambda instead.
by Cynthia Rodas 4H
Sun Oct 27, 2019 8:48 pm
Forum: DeBroglie Equation
Topic: 1.3
Replies: 2
Views: 42

Re: 1.3

Since the problem is asking you to find the amount of power produced in watts, you would use the equation: E = \frac{hc}{\lambda } This would help you find the energy per photon. So then, you plug in Planck's constant (6.62608 x 10 -34 J.s), the speed of light (2.998 x 10 8 m/s) and the given wavele...
by Cynthia Rodas 4H
Sun Oct 27, 2019 8:13 pm
Forum: Ionic & Covalent Bonds
Topic: Double bond placement
Replies: 15
Views: 89

Re: Double bond placement

You can use the octet rule, but I personally like to look at bonding preferences, such as how hydrogen has one bond, oxygen has two bonds, nitrogen has three bonds, and carbon has four bonds.
by Cynthia Rodas 4H
Sun Oct 27, 2019 8:07 pm
Forum: Ionic & Covalent Bonds
Topic: Covalent Bonds
Replies: 11
Views: 74

Re: Covalent Bonds

Covalent bonds can only be formed by nonmetals, and metals are more likely to form ionic bonds. Remember that metals often times become cations because it is easier for them to give up electrons. Non metals have high ionization energy. Nonmetals can also form ionic bonds, right? An ionic bond is ty...
by Cynthia Rodas 4H
Sun Oct 20, 2019 8:31 pm
Forum: Properties of Light
Topic: 1A.9 Energy of Photon
Replies: 12
Views: 78

Re: 1A.9 Energy of Photon

This problem in particular requires the use of two equations: c= (wavelength)(frequency) E = h v E represents the energy of a photon h represents Planck's constant (6.626 x 10[/sup]-34[/sup] J * s) v represents the frequency of radiation Since the first and third parts of the problem provide you wit...
by Cynthia Rodas 4H
Sun Oct 20, 2019 7:56 pm
Forum: Properties of Light
Topic: What are the units of hertz
Replies: 41
Views: 234

Re: What are the units of hertz

Victoria Otuya 4F wrote:Is hz the same as s-1?


Hz is one cycle per second (1/s) and it is the same as s-1. It just becomes s-1 since it is read in the numerator rather than the denominator.
by Cynthia Rodas 4H
Sun Oct 20, 2019 7:49 pm
Forum: Properties of Light
Topic: Question 1A.3
Replies: 3
Views: 32

Re: Question 1A.3

I think the best way to approach this problem is to reason through each choice to see why each one does or doesn't happen. So for example: (a) The speed of radiation doesn't decrease as the frequency of electromagnetic radiation decreases since it is a constant (c= 2.998 x 10 8 m/s). (b) The wavelen...
by Cynthia Rodas 4H
Sun Oct 20, 2019 7:17 pm
Forum: Properties of Light
Topic: Question 1A.15
Replies: 5
Views: 55

Re: Question 1A.15

The equation we will be using to solve this problem is: \nu = R (\frac{1}{n_{1}^{2}}- \frac{1}{n_{2}^{2}}) So the problem states that the spectral line 102.6 nm is in the ultraviolet spectrum of atomic hydrogen. We already know that the Lyman series is the set of lines in the ultraviolet reg...
by Cynthia Rodas 4H
Sun Oct 20, 2019 2:33 pm
Forum: Properties of Light
Topic: Unit for Wavelength
Replies: 34
Views: 160

Re: Unit for Wavelength

c = \lambda \nu The standard units are: c= Speed of Light in meters per second (m/s) \lambda = wavelength in meters (m) \nu = frequency in Hertz (Hz or 1/s) However, the wavelength can be in other length units if the problem states otherwise. In that case, you would have to use dimensional analysis.
by Cynthia Rodas 4H
Sun Oct 13, 2019 4:55 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: E 17
Replies: 4
Views: 74

Re: E 17

Parts (a) and (b) use the equation m= n * M.
m- mass of the sample
n- amount in moles
M- molar mass

Part (c) uses the equation n = N/NA
n- amount in moles
N- number of objects
NA- Avogadro's constant
by Cynthia Rodas 4H
Sun Oct 13, 2019 3:35 pm
Forum: Balancing Chemical Reactions
Topic: Combustion
Replies: 17
Views: 211

Re: Combustion

Combustion refers to a chemical reaction that includes burning in air. The most basic set-up is usually:
O
The main point is that the products will always include CO2 and H2O. It's just a matter of balancing the equation based on what is given to you.
by Cynthia Rodas 4H
Sun Oct 13, 2019 3:10 pm
Forum: Balancing Chemical Reactions
Topic: When are atoms lost or created?
Replies: 14
Views: 198

Re: When are atoms lost or created?

The law of conservation of mass states that atoms are neither created or destroyed. Therefore, if a chemical reaction occurs, then the chemical formula will result in the reactants and/or products being multiplied by factors that result in the same number of atoms.
by Cynthia Rodas 4H
Sun Oct 13, 2019 2:56 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Theoretical vs. Actual Yield
Replies: 38
Views: 442

Re: Theoretical vs. Actual Yield

The actual yield will most of the time be less than the theoretical yield because of competing reactions, measurement errors, and/or limiting reactants. The theoretical yield is the maximum quantity of product that can be obtained from a chemical reaction.
by Cynthia Rodas 4H
Sun Oct 13, 2019 9:19 am
Forum: SI Units, Unit Conversions
Topic: Practice Problems?
Replies: 11
Views: 159

Re: Practice Problems?

If you want more practice problems aside from the ones Lavelle assigned, I would highly recommend participating in the Step-Up Program and Workshops. Some clubs also provide their own Peer Learning Groups for certain subjects. Khan Academy is also a great resource to use.
by Cynthia Rodas 4H
Sat Oct 05, 2019 10:49 am
Forum: Empirical & Molecular Formulas
Topic: Empirical Formula Purpose
Replies: 13
Views: 141

Re: Empirical Formula Purpose

Empirical formulas show the relative number of atoms a molecule has. The ratio can then be used to determine the molecular formula, which is the actual number of atoms in a molecule. However, there are some cases in which the empirical formula is also the molecular formula.
by Cynthia Rodas 4H
Sat Oct 05, 2019 10:27 am
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Avogadro's number
Replies: 9
Views: 85

Re: Avogadro's number

Hey, I was just curious. What does Avogadro's number actually represent? Thank you guys. :) Avogadro’s number is referring to the pure number “6.0221 x 10^23,” which is unitless. On the other hand, Avogadro’s constant is a constant with units, 6.0221 x 10^23 mol^-1, which represents the number of o...
by Cynthia Rodas 4H
Wed Oct 02, 2019 3:28 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Balancing Equations [ENDORSED]
Replies: 25
Views: 473

Re: Balancing Equations [ENDORSED]

When balancing equations how do you determine what to balance first? My TA recommended that we start with balancing the elements that appear the least in a chemical equation. For example: C_{4}H_{10} + O_{2} \rightarrow CO_{2} + H_{2}O You would start with either the Carbons or Hydrogens since they...
by Cynthia Rodas 4H
Tue Oct 01, 2019 7:14 pm
Forum: Significant Figures
Topic: Rounding the elements
Replies: 12
Views: 114

Re: Rounding the elements

I would recommend using the exact values provided by the periodic table and then use the significant figure rules at the end of the calculation to round off properly.
by Cynthia Rodas 4H
Tue Oct 01, 2019 7:06 pm
Forum: Empirical & Molecular Formulas
Topic: Rounding [ENDORSED]
Replies: 12
Views: 131

Re: Rounding [ENDORSED]

I just looked over Dr. Lavelle’s worksheet regarding significant figures. According to Lavelle, one of the rules for rounding off is to wait until the end of a calculation. For calculations using multiplication and division, your answer should have the same number of significant figures as the value...
by Cynthia Rodas 4H
Tue Oct 01, 2019 6:11 pm
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student - Part II [ENDORSED]
Replies: 130
Views: 2938

Re: Advice from a Medical Student - Part II [ENDORSED]

Thank you so much for sharing your experience as a medical student! It is truly inspiring to hear about all the things you have accomplished over the past three years. I am also pursuing a career in medicine. However, I am a first-generation student and I have no family members or friends who are in...

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