## Search found 100 matches

Sun Mar 15, 2020 8:47 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Doing work vs work done
Replies: 8
Views: 153

### Re: Doing work vs work done

W is positive when work is being done ON the system and negative when the system is doing the work.
Sun Mar 15, 2020 8:45 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Affecting E cell
Replies: 4
Views: 115

### Re: Affecting E cell

If the reaction was at equilibrium, changing the concentrations will shift the equilibrium and change from standard E cell to E cell.
Sun Mar 15, 2020 8:43 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Fast Reactions
Replies: 4
Views: 80

### Re: Fast Reactions

If the reaction is very fast, the rate changes more rapidly than the time required to measure it. The reaction may be finished before an initial rate can be observed.
Sun Mar 15, 2020 8:41 pm
Forum: General Rate Laws
Topic: Overall Order
Replies: 6
Views: 119

### Re: Overall Order

Add the exponents of all the reactants in the rate equation.
Mon Mar 09, 2020 3:03 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: HW 7D.5
Replies: 2
Views: 36

### HW 7D.5

What are the correct units for the answer? In the textbook, it's
2.7x10^10 mol.L-1.s-1 and in the solutions manual it's 2.7x10^10 L.mol-1.s-1
Sun Mar 08, 2020 10:35 pm
Forum: General Rate Laws
Topic: 7A.7 Units of Rate Constants
Replies: 2
Views: 47

### Re: 7A.7 Units of Rate Constants

Organic Chem tutor used k=M^(1-n).s^-1.
Sun Mar 08, 2020 10:32 pm
Forum: General Rate Laws
Topic: Changing the mass of electrodes
Replies: 6
Views: 53

### Re: Changing the mass of electrodes

Mass doesn't affect the E(cell) but concentration does.
Sun Mar 08, 2020 10:24 pm
Forum: General Rate Laws
Topic: Rate constant vs. rate
Replies: 4
Views: 46

### Re: Rate constant vs. rate

You can use rate constant to calculate the rate. Rate constant doesn't change while rate does.
Sun Mar 08, 2020 10:19 pm
Forum: General Rate Laws
Topic: 7B3a
Replies: 3
Views: 60

### Re: 7B3a

0.693 came from ln(2) which is in the half life equation for first order reactions. t=ln(2)/k
Sun Mar 08, 2020 10:18 pm
Forum: General Science Questions
Topic: Worksheets for Final Review Sessions
Replies: 2
Views: 121

### Re: Worksheets for Final Review Sessions

You can search up some of the TAs names on Chem Com, go to step-up, or workshops.
Sun Mar 01, 2020 8:26 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Nernst Equation
Replies: 3
Views: 49

### Re: Nernst Equation

You derive it from the equations: ΔG=ΔG°+RT(ln(Q)) and ΔG=-nFE. You set the two equal to each other to get: -nFE=ΔG°+RT(ln(Q)). Divide both sides by -nF to get: E=(ΔG°/-nF)-RT(ln(Q))/nF) From ΔG°=-nFE°, you change it to E°=ΔG°/-nF to replace the first part of the equation to get: E=E°-(RT/nF) x ln(Q)
Sun Mar 01, 2020 8:03 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Diagrams
Replies: 6
Views: 65

### Cell Diagrams

When we write cell diagrams, and there are two ions ex: Fe2+ and Fe3+ both in aqueous solution. I know you don't separate it with the line (|) and instead, you separate it with a comma. But does it matter what order I write them in? Can I write them as either Fe2+,Fe3+ OR Fe3+,Fe2+?
Sun Mar 01, 2020 7:59 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: delta G=-nFE
Replies: 7
Views: 143

### Re: delta G=-nFE

You can find it by balancing the electrons of the half-reactions and that's the n, the amount in moles of electrons that were transferred.
Sun Mar 01, 2020 7:58 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: How to tell what rxn to use
Replies: 2
Views: 100

### Re: How to tell what rxn to use

If you write out the original reaction, you can see that the oxidation number of Cl doesn't change whereas Fe does.
Sat Feb 29, 2020 12:07 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: HW 6L.7 (c)
Replies: 1
Views: 36

### HW 6L.7 (c)

Problem asks to write the half-reactions and devise a galvanic cell (write a cell diagram) to study each of the following reactions. (c) Cd(s) + 2Ni(OH)3(s) --> Cd(OH)2(s) + 2Ni(OH)2(s), the reaction in nickel-cadmium cell I found the two half-reactions which were: Cd(s) + 2OH-(aq) --> Cd(OH)2 + 2e-...
Sun Feb 23, 2020 7:49 pm
Forum: Administrative Questions and Class Announcements
Topic: Is this course curved?
Replies: 7
Views: 183

### Re: Is this course curved?

It's 50% to get a C- in the class and he probably rounds your grade at the end if you're really close.
Sun Feb 23, 2020 7:47 pm
Forum: Administrative Questions and Class Announcements
Topic: Test 2
Replies: 15
Views: 263

### Test 2

Is test 2 just going to include the material that wasn't tested on the midterm up to what we learn before the test?
Sun Feb 23, 2020 7:43 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: chemistry community posts
Replies: 12
Views: 84

### Re: chemistry community posts

Our TA said that there's a system that automatically checks your chemistry community posts.
Sun Feb 23, 2020 7:38 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Le Chatelier's Principle
Replies: 1
Views: 16

### Le Chatelier's Principle

How does Le Chatelier's Principle apply to cell potentials?
Sun Feb 23, 2020 7:35 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: cell diagrams
Replies: 5
Views: 71

### cell diagrams

How do you write the redox reaction or draw cell diagrams when you're given two half-reactions?
Sun Feb 16, 2020 9:43 pm
Forum: Administrative Questions and Class Announcements
Topic: HW7
Replies: 14
Views: 170

### Re: HW7

Probably anything from the end of thermodynamics and beginning of electrochemistry.
Sun Feb 16, 2020 7:46 pm
Forum: Van't Hoff Equation
Topic: Van't Hoff Equation
Replies: 3
Views: 31

### Van't Hoff Equation

When would you use the Van't Hoff Equation and what does it mean?
Sun Feb 16, 2020 7:43 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: delta S=qrev/t
Replies: 4
Views: 49

### Re: delta S=qrev/t

Sometimes it's given to you and other times, you're given the information to calculate it.
Sun Feb 16, 2020 7:42 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: delatG= -RTInK
Replies: 4
Views: 86

### Re: delatG= -RTInK

Because it relates the difference in Standard Gibbs Free Energy to K.
Sun Feb 16, 2020 7:34 pm
Forum: Calculating Work of Expansion
Topic: Work Equation
Replies: 6
Views: 197

### Re: Work Equation

Work under constant volume is 0. Under constant pressure, you'd use w=-P(external)Delta V. Under constant temperature when it's reversible and isothermal, you'd use w=-nRTln(Vf/Vi).
Sun Feb 09, 2020 9:44 pm
Forum: Calculating Work of Expansion
Topic: 4A.9
Replies: 2
Views: 39

### Re: 4A.9

the final temperature would be the same so you set qCu=-qWater and solve.
Tue Feb 04, 2020 11:45 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Question 4.C.9
Replies: 1
Views: 32

### Re: Question 4.C.9

For Part 1) You would calculate the heat (q) required to heat the copper kettle and water to 100 C separately. Then you add them together to find the total heat needed to raise the temperature. Use q=nCdeltaT for both. For Part 2) You would divide the heat required to heat the water by the total hea...
Tue Feb 04, 2020 11:12 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: closed system
Replies: 7
Views: 97

### Re: closed system

Since it's sealed, no matter can be removed or added but heat can still be transferred so it's a closed sytem.
Tue Feb 04, 2020 11:11 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Enthalpy
Replies: 2
Views: 24

### Re: Enthalpy

These changes occur when reactions require energy or release energy.
Tue Feb 04, 2020 11:09 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Ideal Gas Heat Capacities
Replies: 1
Views: 24

### Re: Ideal Gas Heat Capacities

I think it'd be a good idea to know them and how to apply it since Lavelle did assign the reading so it's fair game.
Sun Feb 02, 2020 9:28 pm
Forum: Calculating Work of Expansion
Topic: 4A.5
Replies: 2
Views: 56

### Re: 4A.5

It means that the constant temperature of the gas is maintained by ensuring that the system is in thermal contact with a constant-temperature water bath at all stages of the expansion. In an isothermal expansion, the pressure of the gas falls as it expands; therefore, to achieve reversible expansion...
Sun Feb 02, 2020 9:20 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: 4A.13
Replies: 2
Views: 41

### Re: 4A.13

In the first equation, you're calculating for the heat capacity of the Calorimeter using the heat put into the Calorimeter which is why it's qcal. In the second equation, you use it to calculate the heat of the overall change in internal energy from the 2 rises in temperature.
Sun Feb 02, 2020 9:16 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Changing the energy of a system
Replies: 9
Views: 62

### Re: Changing the energy of a system

The three ways to change the energy of a system is heat, work, and mass flow.
Sun Feb 02, 2020 9:12 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: 4B.5
Replies: 3
Views: 44

### 4B.5

An ideal gas in a cylinder was placed in a heater and gained 5.50 kJ of energy as heat. If the cylinder increased in volume from 345 mL to 1846 mL against an atmospheric pressure of 750. Torr during this process, what is the change in internal energy of the gas in the cylinder?

How do we solve this?
Sun Feb 02, 2020 6:07 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: 4A.13
Replies: 3
Views: 28

### 4A.13

Problem: A constant-volume calorimeter was calibrated by carrying out a reaction known to release 3.50 kJ of heat in 0.200 L of solution in the calorimeter (q 5 23.50 kJ), resulting in a temperature rise of 7.32 C. In a subsequent experiment, 100.0 mL of 0.200 m HBr(aq) and 100.0 mL of 0.200 m KOH(a...
Sun Jan 26, 2020 9:18 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5% Rule
Replies: 9
Views: 81

### Re: 5% Rule

If X is less than 5% of the initial, you should be on the right track!
Sun Jan 26, 2020 9:16 pm
Forum: Phase Changes & Related Calculations
Topic: Enthalpy Calculations
Replies: 5
Views: 36

### Re: Enthalpy Calculations

I think it's helpful to know the generic formulas for liquid to vapor, solid to liquid, and solid to vapor which make up the formula (Delta H sublimation)=(Delta H fusion) + (Delta H vapor).
Sun Jan 26, 2020 9:13 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Exothermic and Endothermic
Replies: 11
Views: 424

### Re: Exothermic and Endothermic

Exothermic reactions have a negative value because it releases energy so products are lower than reactants. Vice versa for endothermic reactions which have a positive value because it requires energy so the reactants are lower than the products.
Sun Jan 26, 2020 9:10 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Meaning of State Function
Replies: 8
Views: 64

### Re: Meaning of State Function

A state function is not dependent on the path taken to obtain that state. One example is density which only depends on the initial and final, not the path taken.
Sun Jan 26, 2020 9:07 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Negative Square Root solving an ICE box
Replies: 13
Views: 103

### Re: Negative Square Root solving an ICE box

Usually, you shouldn't get a negative number inside the square root. Outside the square root, it can be positive and negative.
Sun Jan 19, 2020 8:23 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm and final
Replies: 6
Views: 84

### Re: Midterm and final

I think the midterm and final is cumulative but not the tests.
Sun Jan 19, 2020 8:19 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K vs Q
Replies: 14
Views: 88

### Re: K vs Q

K is used when a reaction is at equilibrium. Q can be used at any arbitrary stage of a reaction.
Sun Jan 19, 2020 8:12 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: exothermic/endothermic rxns
Replies: 4
Views: 48

### Re: exothermic/endothermic rxns

Raising the temperature of an exothermic reaction lowers the K value and shifts to favor the production of reactants. On the other hands, raising the temperature of an endothermic reaction raises the K value and shifts to favor the production of products.
Sun Jan 19, 2020 8:06 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5%
Replies: 4
Views: 41

### Re: 5%

You're allowed to approximate X while doing ICE tables if the K constant is less than 1.0x10^-3. If the answer is less than 5% of the initial molarity, then the approximation is okay.
Sun Jan 19, 2020 8:03 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Shift Of Reaction
Replies: 4
Views: 86

### Re: Shift Of Reaction

A reaction shifts left or right in order to reach equilibrium again if something such as concentration or temperature changed.
Sun Jan 12, 2020 9:14 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Calculating for Pressure
Replies: 5
Views: 57

### Re: Calculating for Pressure

Usually, temperature should be given so you can use PV=nRT to solve for pressure.
Sun Jan 12, 2020 9:00 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Partial Pressure
Replies: 19
Views: 143

### Re: Partial Pressure

It should be given usually.
Sun Jan 12, 2020 8:54 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Le Chatelier's Principle
Replies: 5
Views: 43

### Le Chatelier's Principle

What exactly is Le Chatelier's Principle?
Sun Jan 12, 2020 6:25 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: memorization
Replies: 12
Views: 127

### Re: memorization

I don't think so, we should be given it on exams.
Sun Jan 12, 2020 6:17 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Q>K
Replies: 9
Views: 80

### Re: Q>K

When there is more product than reactants and the reverse reaction is favored.
Sun Dec 08, 2019 10:26 pm
Forum: *Titrations & Titration Calculations
Topic: Type of Titration
Replies: 3
Views: 113

### Re: Type of Titration

If the pH of the titration is >7, it's basic. If it's <7, it's basic. If pH is 7, it's neutral.
Sun Dec 08, 2019 10:20 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Uncertainty
Replies: 5
Views: 160

### Re: Uncertainty

Delta X is the uncertainty in position.
Sun Dec 08, 2019 10:18 pm
Forum: Identifying Acidic & Basic Salts
Topic: Types of Salts
Replies: 4
Views: 177

### Re: Types of Salts

No
Sun Dec 08, 2019 10:49 am
Forum: Naming
Topic: Naming
Replies: 7
Views: 185

### Re: Naming

use these when the ligand already has a prefix of bi- tri- tetra- etc.
Wed Dec 04, 2019 10:39 pm
Forum: Naming
Topic: Naming Compounds
Replies: 2
Views: 52

### Naming Compounds

When we name coordination compounds on the final, would writing (en) in place of ethylenediamine or (dien) in place of diethylenetriamine be acceptable?
Sun Dec 01, 2019 10:40 pm
Forum: General Science Questions
Topic: Bruincasts
Replies: 9
Views: 308

### Re: Bruincasts

Lavelle doesn't bruincast his lectures but his website does have modules that you might find helpful.
Sun Dec 01, 2019 10:37 pm
Forum: Lewis Acids & Bases
Topic: Weak vs. Strong
Replies: 8
Views: 269

### Re: Weak vs. Strong

Strong acids completely ionize in solution while strong bases completely ionize in water.
Sun Dec 01, 2019 10:29 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: Acid strength relative to kA
Replies: 2
Views: 37

### Re: Acid strength relative to kA

Stronger acids have higher kA and lower pKA while weaker acids have lower kA and higher pKA.
Sun Dec 01, 2019 10:27 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Equilibrium constants
Replies: 3
Views: 49

### Re: Equilibrium constants

The equilibrium constant kA is a quantitative measure of the strength of an acid in a solution. The pKa is used to indicate the strength of an acid.
Sun Dec 01, 2019 10:11 pm
Forum: Student Social/Study Group
Topic: Studying for Final
Replies: 7
Views: 229

### Re: Studying for Final

Go to Lyndon's review sessions!
Sun Nov 24, 2019 10:20 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: bronsted acid
Replies: 5
Views: 63

### Re: bronsted acid

A bronsted acid is a substance that gives up or donates hydrogen ions during a chemical reaction.
Sun Nov 24, 2019 10:17 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Final
Replies: 10
Views: 137

### Re: Final

Yes, Lavelle has mentioned in class before that the final will be cumulative of everything we've learned this quarter.
Sun Nov 24, 2019 10:13 pm
Forum: Hybridization
Topic: Bond Strength
Replies: 2
Views: 45

### Re: Bond Strength

As the orbitals in the bond have more s character, the bond length generally decreases so the strength increases.
Sun Nov 24, 2019 2:16 pm
Forum: Naming
Topic: 9C. 3
Replies: 2
Views: 28

### Re: 9C. 3

K3[Cr(CN)6]
Tue Nov 19, 2019 9:38 pm
Forum: Student Social/Study Group
Topic: Lydon's Week 8 Learning Session
Replies: 4
Views: 151

### Lydon's Week 8 Learning Session

Does anyone have the answers to Lydon's worksheet this week?
Sun Nov 17, 2019 7:11 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Repulsion strength and Bond Angles
Replies: 12
Views: 131

### Re: Repulsion strength and Bond Angles

Yes because the molecule with the lone pair would create repulsion that would alter the degrees of the bond angles.
Sun Nov 17, 2019 7:08 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Electronic arrangement vs molecular shape
Replies: 4
Views: 38

### Re: Electronic arrangement vs molecular shape

The electronic arrangement factors in both bonding pairs and lone pairs. The molecular shape takes into consideration of the lone pairs. So an atom's electronic arrangement and molecular shape can be the same if there aren't any lone pairs.
Sun Nov 17, 2019 7:00 pm
Forum: Photoelectric Effect
Topic: Evidence of Waves Having Properties of Matter
Replies: 1
Views: 116

### Re: Evidence of Waves Having Properties of Matter

The Davisson–Germer experiment confirmed the de Broglie hypothesis that matter has wave-like behavior.
Sun Nov 17, 2019 6:54 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR Angles
Replies: 4
Views: 88

### Re: VSEPR Angles

The areas of electron density and lone pairs affect bond angles while atomic radius affects the bond length.
Sun Nov 17, 2019 4:58 pm
Forum: Trends in The Periodic Table
Topic: trends on test 2
Replies: 4
Views: 160

### Re: trends on test 2

Test 2 will cover anything that wasn't tested on the midterm up to sigma and pi bonds which he will discuss in class on Monday I believe.
Sun Nov 10, 2019 10:34 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Oxidation Number
Replies: 6
Views: 83

### Re: Oxidation Number

The oxidation number of an atom is the charge that an atom would have if the compound was composed of ions. The oxidation number of each atom can be calculated by subtracting the sum of lone pairs and electrons it gains from bonds from the number of valence electrons.
Sun Nov 10, 2019 10:32 pm
Forum: Octet Exceptions
Topic: electron number in octet
Replies: 8
Views: 211

### Re: electron number in octet

It depends on what element it is. Common examples of elements that can form an expanded octet is sulfur, phosphorus, silicon, and chlorine.
Sun Nov 10, 2019 10:13 pm
Forum: Electronegativity
Topic: Electron affinity
Replies: 6
Views: 105

### Re: Electron affinity

Electronegativity measures the tendency of an atom to attract a bonding pair of electrons. Electron affinity is the change in energy of a neutral atom when an electron is added to the atom to form a negative ion. Electron affinity and electronegativity both increase from left to right in a period an...
Sun Nov 10, 2019 10:03 pm
Forum: Student Social/Study Group
Topic: Chem 14B
Replies: 10
Views: 251

### Re: Chem 14B

I think I am if I get the class!
Sun Nov 10, 2019 1:55 pm
Forum: Electronegativity
Topic: Ionization energy of O vs N
Replies: 6
Views: 168

### Re: Ionization energy of O vs N

The ionization energy trend in the periodic table has a few exceptions with oxygen and nitrogen being one of them. The ionization energy of oxygen is lower than nitrogen because each p-orbital in a nitrogen atom is occupied by one electron but in oxygen, the first orbital is occupied by a pair of el...
Sun Nov 03, 2019 9:02 pm
Forum: Electronegativity
Topic: Defining electronegativity
Replies: 2
Views: 48

### Re: Defining electronegativity

Electronegativity is a measure of how strongly atoms attract bonding electrons to themselves.
Sun Nov 03, 2019 8:54 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Aufbau vs Hunds
Replies: 6
Views: 205

### Re: Aufbau vs Hunds

The Aufbau principle states that lower energy orbitals fill before higher energy orbitals. Hund's Rule states that one electron goes into each orbital until all of them are half full before pairing up.
Sun Nov 03, 2019 8:44 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configuration for cations
Replies: 3
Views: 67

### Re: Electron Configuration for cations

Yes, you remove an electron from the highest energy level.
Sun Nov 03, 2019 8:42 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: 4s or 3d first?
Replies: 14
Views: 385

### Re: 4s or 3d first?

My TA said that we should write 3d first so the shells are in chronological order.
Sun Nov 03, 2019 1:23 pm
Forum: Lewis Structures
Topic: Central Atom
Replies: 3
Views: 29

### Re: Central Atom

The central atom is usually the least electronegative atom with the most unpaired valence electrons. If carbon is present, often times, the central atom is carbon. However, hydrogen can never be a central atom.
Sun Oct 27, 2019 8:43 pm
Forum: Ionic & Covalent Bonds
Topic: What is the difference between an anion and cation?
Replies: 7
Views: 119

### Re: What is the difference between an anion and cation?

The net electrical charge of an anion is negative and a cation is positive. For example, sulfate is an anion and ammonium is a cation.
Sun Oct 27, 2019 8:31 pm
Forum: Lewis Structures
Topic: Orbitals
Replies: 9
Views: 141

### Re: Orbitals

Usually, you remove electrons from the farthest orbital so yes, you do.
Sun Oct 27, 2019 8:05 pm
Forum: Ionic & Covalent Bonds
Topic: Metalloids
Replies: 5
Views: 67

### Re: Metalloids

Metalloids can form covalent and ionic bonds. They can form covalent bonds by sharing electrons or ionic bonds by either losing or gaining electrons.
Sun Oct 27, 2019 8:00 pm
Forum: Lewis Structures
Topic: Choosing the central atom
Replies: 16
Views: 219

### Re: Choosing the central atom

Dr. Lavelle said during lecture to use the least electronegative atom as the central atom. In the case that carbon is present in the ion, it's usually the central atom.
Sun Oct 27, 2019 7:56 pm
Forum: Electronegativity
Topic: Electronegativity
Replies: 14
Views: 147

### Re: Electronegativity

Electronegativity describes the likelihood of an atom to attract a shared pair of electrons towards itself. It increases from left to right because of a greater charge on the nucleus which causes the electron bonding pairs to be attracted to atoms placed further right on the periodic table.
Sun Oct 20, 2019 11:01 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: What is electron configuration?
Replies: 3
Views: 44

### Re: What is electron configuration?

Electron configuration is the distribution of electrons of an atom or molecule in atomic or molecular orbitals. It tells you how many electrons there are in each of the different orbitals and at which energy level.
Sun Oct 20, 2019 8:49 pm
Forum: Properties of Light
Topic: What are the units of hertz
Replies: 41
Views: 502

### Re: What are the units of hertz

The unit for hertz is the number of cycles per second which basically measures frequency.
Sun Oct 20, 2019 8:37 pm
Forum: Limiting Reactant Calculations
Topic: general questions
Replies: 11
Views: 486

### Re: general questions

Finding the limiting reactant helps to determine the amount of a product that can be produced or how much of a reactant will react with the limiting reactant.
Sun Oct 20, 2019 8:31 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Pauli Exclusion Principle
Replies: 9
Views: 533

### Re: Pauli Exclusion Principle

It basically says that in an atom or a molecule, 2 electrons can’t have the same four electronic quantum numbers. The two electrons in an orbital must have opposite spins.
Thu Oct 17, 2019 7:50 pm
Forum: DeBroglie Equation
Topic: the m in the de broglie equation
Replies: 5
Views: 66

### Re: the m in the de broglie equation

yes, m is the mass of the particle.
Sun Oct 13, 2019 10:30 pm
Forum: Trends in The Periodic Table
Topic: Element Names
Replies: 8
Views: 627

### Re: Element Names

You should be using the periodic table on Lavelle's website to familiarize yourself with it since that's the one we'll be using on all of our tests.
Sun Oct 13, 2019 10:23 pm
Forum: Properties of Electrons
Topic: Photons
Replies: 9
Views: 147

### Re: Photons

If a photon has less energy than the work function, it would not be able to eject electrons.
Sun Oct 13, 2019 10:18 pm
Forum: General Science Questions
Topic: Powerpoint Slides
Replies: 4
Views: 96

### Re: Powerpoint Slides

No I don't think he does. You can check the different links he has on his website if you're uncertain.
Sun Oct 13, 2019 10:07 pm
Forum: Properties of Electrons
Topic: Photon
Replies: 5
Views: 39

### Re: Photon

A photon is a particle representing a quantum of light or other electromagnetic radiation. It carries energy proportional to the radiation frequency but has zero rest mass.
Sun Oct 13, 2019 10:03 pm
Forum: Significant Figures
Topic: sig figs and periodic tables
Replies: 11
Views: 407

### Re: sig figs and periodic tables

Use the periodic table Lavelle put on his website. It's the one that they gave us on the test.
Sun Oct 06, 2019 12:38 am
Forum: Molarity, Solutions, Dilutions
Topic: Which Volume to use for M1
Replies: 6
Views: 85

### Re: Which Volume to use for M1

it depends on what the question is asking for. Usually you would use the smaller one
Sun Oct 06, 2019 12:36 am
Forum: Einstein Equation
Topic: Planack's constant
Replies: 8
Views: 201

### Re: Planack's constant

it is used to find E=hv. It can be used with c=lv to calculate and find values
h is planck's constant
Sun Oct 06, 2019 12:32 am
Forum: Administrative Questions and Class Announcements
Topic: Test
Replies: 2
Views: 55

### Re: Test

Yes, my TA told our discussion section that they're modeled after the homework questions. So, only free response.
Sun Oct 06, 2019 12:18 am
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Naming Compounds
Replies: 3
Views: 97

### Re: Naming Compounds

in the textbook, there is a page under the fundamentals section that goes over how to name ionic and covalent compounds. Also it has a list of the most common polyatomic ions like chlorate, carbonate, sulfate, nitrate, and etc.
Sun Oct 06, 2019 12:17 am
Forum: Empirical & Molecular Formulas
Topic: Order of elements in formulas
Replies: 5
Views: 87