Search found 30 matches

by Erin Li 1K
Tue Jun 12, 2018 3:16 am
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7348
Views: 918773

Re: Post All Chemistry Jokes Here

I don't trust atoms...I heard they make up everything.
by Erin Li 1K
Sat Jun 02, 2018 9:00 pm
Forum: Electronegativity
Topic: Calculating electronegativity
Replies: 10
Views: 388

Re: Calculating electronegativity

we do not need to know how to calculate electronegativities. However, the trend is that EN increases towards an upwards diagonal to the right. it decreases down a column and increases across a row.
by Erin Li 1K
Sat Jun 02, 2018 8:55 pm
Forum: Electronegativity
Topic: Test 3. Question 7.
Replies: 6
Views: 264

Re: Test 3. Question 7.

Differences in electronegavity determine the ionic character. the higher the difference in electronegativity, the greater the ionic character
by Erin Li 1K
Sat Jun 02, 2018 8:51 pm
Forum: Sigma & Pi Bonds
Topic: Detail of Bonds
Replies: 3
Views: 218

Re: Detail of Bonds

a sigma bond is one single covalent bond
so for single, double, and triple bonds,
a single bond=1 sigma bond
a double bond=1 sigma bond+1 pi bond
a triple bond=1 sigma bond+2 pi bonds
by Erin Li 1K
Sat Jun 02, 2018 8:49 pm
Forum: Resonance Structures
Topic: Resonance Structures
Replies: 9
Views: 387

Re: Resonance Structures

No, resonance structures do not have to have the same formal charge for each element. however, the overall formal charge should be the same. For example, if it was No3-, overall it should have a -1 formal charge for the -
by Erin Li 1K
Sat Jun 02, 2018 8:46 pm
Forum: Hybridization
Topic: VSEPR
Replies: 11
Views: 474

Re: VSEPR

VSEPR stands for valence shell electron pair repulsion and it achieves the geometry that has the least electron repulsion
by Erin Li 1K
Sat Jun 02, 2018 8:45 pm
Forum: Hybridization
Topic: σ bonds
Replies: 9
Views: 241

Re: σ bonds

a sigma bond is when there is one single covalent bond
however, double bonds and triple bonds also have a sigma bond
by Erin Li 1K
Wed May 23, 2018 1:26 am
Forum: Ionic & Covalent Bonds
Topic: Octet rule
Replies: 17
Views: 464

Re: Octet rule

atoms are most stable when they have eight electrons. However, there are exceptions to this like hydrogen which only has one electron.
by Erin Li 1K
Wed May 23, 2018 1:23 am
Forum: Lewis Structures
Topic: lowest energy & most stable Lewis structures
Replies: 4
Views: 360

Re: lowest energy & most stable Lewis structures

you would have to calculate the formal charge by the equation:
formal charge = number of valence - lone electrons - (shared electrons/2)
by Erin Li 1K
Wed May 23, 2018 1:22 am
Forum: Lewis Structures
Topic: H Formal Charge
Replies: 4
Views: 139

Re: H Formal Charge

Hydrogen really only has one electron even when bonding and there is no exception to that, so when Hydrogen has only one electron (which is always the case) it has a formal charge of 0
by Erin Li 1K
Wed May 23, 2018 1:20 am
Forum: Ionic & Covalent Bonds
Topic: Formal charge?
Replies: 12
Views: 425

Re: Formal charge?

you calculate formal charge by using the equation
number of valence electrons - number of lone electrons and number of bonds
by Erin Li 1K
Wed May 23, 2018 1:18 am
Forum: Ionic & Covalent Bonds
Topic: ionic character
Replies: 10
Views: 253

Re: ionic character

greater ionic character means greater difference in electronegativity
by Erin Li 1K
Wed May 23, 2018 1:15 am
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR on test 3?
Replies: 3
Views: 115

VSEPR on test 3?

Will VSEPR be on test three? or is it just lewis structures?
by Erin Li 1K
Sat Apr 28, 2018 1:05 am
Forum: Properties of Electrons
Topic: Information Provided on Exam
Replies: 6
Views: 277

Re: Information Provided on Exam

No this will not be provided
by Erin Li 1K
Sat Apr 28, 2018 1:04 am
Forum: Properties of Light
Topic: Rydberg Formula for Atomic Hydrogen [ENDORSED]
Replies: 4
Views: 234

Re: Rydberg Formula for Atomic Hydrogen [ENDORSED]

it's E(n) = -(hR)/nfinal^2 -(hR)/ninitial^2
and for frequency it is = R [(1/nfinal^2) - (1/ninitial^2)]
by Erin Li 1K
Tue Apr 24, 2018 11:53 pm
Forum: Photoelectric Effect
Topic: Frequency on Photoelectric Effect
Replies: 5
Views: 208

Frequency on Photoelectric Effect

If a certain frequency is not ejecting electrons. Does increasing frequency eject electrons?
Also what increases the number of electrons ejected?
by Erin Li 1K
Thu Apr 19, 2018 1:59 am
Forum: Photoelectric Effect
Topic: Lyman vs. Balmer vs. Paschen vs. Brackett?
Replies: 3
Views: 231

Lyman vs. Balmer vs. Paschen vs. Brackett?

What are the differences between these three series and how do I tell the difference between them?

For example, in problem 1.13 problem b, why is the answer Balmer?
by Erin Li 1K
Tue Apr 17, 2018 11:59 am
Forum: Limiting Reactant Calculations
Topic: moles + limiting reactant
Replies: 2
Views: 188

Re: moles + limiting reactant

you find the moles of each and compare it to the ratios in the chemical equation
or you can use both and the balanced chemical equation see which one produces less product
by Erin Li 1K
Tue Apr 17, 2018 11:54 am
Forum: Ideal Gases
Topic: Reading the textbook [ENDORSED]
Replies: 81
Views: 54727

Re: Reading the textbook [ENDORSED]

I get overwhelmed and intimidated when reading the textbook too, so I would recommend only doing so when you have your full attention to the book and no other distractions.
by Erin Li 1K
Tue Apr 17, 2018 11:52 am
Forum: Ionic & Covalent Bonds
Topic: Types of Bonds
Replies: 10
Views: 343

Re: Types of Bonds

A covalent bond would just be between two nonmetals while an ionic bond is between a nonmetal and a metal! just look at the two elements in the chemical equation
by Erin Li 1K
Thu Apr 12, 2018 3:53 am
Forum: Molarity, Solutions, Dilutions
Topic: Problem G13
Replies: 1
Views: 142

Problem G13

I need help on the following problem (G13 in the textbook): To prepare a fertilizer solution, a florist dilutes 1.0 L of 0.20 m NH4NO3(aq) by adding 3.0 L of water. The florist then adds 100. mL of the diluted solution to each plant. How many moles of nitrogen atoms will each plant receive? Solve th...
by Erin Li 1K
Wed Apr 11, 2018 12:30 am
Forum: Photoelectric Effect
Topic: Module Question 27.A
Replies: 4
Views: 158

Re: Module Question 27.A

with the equation 1/2 times mv^2, you use the KJ/mol to covert the mols to kg for the m part in the equation. The m stands for mass, so you need to convert the mols to kg. Then, Kinetic energy is measure in Joules which is already used in the equation, so some units should cancel out.
by Erin Li 1K
Wed Apr 11, 2018 12:18 am
Forum: Limiting Reactant Calculations
Topic: Mass of Products VS. Mass of Reactants- Class Assessment
Replies: 5
Views: 209

Re: Mass of Products VS. Mass of Reactants- Class Assessment

No; based on the law of conservation of mass, the amount of products is equal to the mass of the reactants since this mass is not created nor destroyed in chemical reactions. They are just bonded differently.
by Erin Li 1K
Wed Apr 11, 2018 12:16 am
Forum: Balancing Chemical Reactions
Topic: Subscripts [ENDORSED]
Replies: 6
Views: 277

Re: Subscripts [ENDORSED]

This means that there are 6N and and only 1 Mn. You would have to take into consideration both elements when balancing the equations. You would generally balance the one that is by itself on the other side last or balance the one first that is easiest to balance corresponding to the other side.
by Erin Li 1K
Wed Apr 11, 2018 12:13 am
Forum: Significant Figures
Topic: Scientific notation [ENDORSED]
Replies: 7
Views: 344

Re: Scientific notation [ENDORSED]

I think either is fine, but generally in chemistry, scientific notation is used. However, Lavelle did mention that significant figures do not matter in this course.
by Erin Li 1K
Wed Apr 11, 2018 12:11 am
Forum: Properties of Electrons
Topic: Electromagnetic Field [ENDORSED]
Replies: 7
Views: 236

Re: Electromagnetic Field [ENDORSED]

I agree. I also think it's arbitrary. None of them technically point upward or to the right, it is just a matter of how they are viewed and at what angles.
by Erin Li 1K
Wed Apr 11, 2018 12:05 am
Forum: SI Units, Unit Conversions
Topic: Units for Answer
Replies: 10
Views: 444

Re: Units for Answer

Most often if it is talking about mass then you would revert back to kg since it is one of the standard units. The standard units are kg, m, and sec which is what are normally used.
by Erin Li 1K
Fri Apr 06, 2018 2:18 pm
Forum: Significant Figures
Topic: Sig Figs [ENDORSED]
Replies: 9
Views: 411

Re: Sig Figs [ENDORSED]

No. Someone asked Lavelle if significant figures matter on tests, and he said no.
by Erin Li 1K
Fri Apr 06, 2018 2:16 pm
Forum: Empirical & Molecular Formulas
Topic: Periodic Table Memorization [ENDORSED]
Replies: 8
Views: 375

Re: Periodic Table Memorization [ENDORSED]

No. We do not need memorize the periodic table components for the first exam! I'm sure they will provide us with needed information and periodic table if necessary.
by Erin Li 1K
Fri Apr 06, 2018 11:37 am
Forum: Administrative Questions and Class Announcements
Topic: Modules
Replies: 5
Views: 184

Re: Modules

They are just posted for extra help on exam materials and used for guidance!

Go to advanced search