Search found 35 matches

by annikaying
Thu Nov 21, 2019 10:35 am
Forum: Dipole Moments
Topic: Melting points
Replies: 4
Views: 27

Re: Melting points

Intermolecular forces are the only thing that determine melting and boiling points. Therefore having a double bond doesn't affect the melting point.
by annikaying
Thu Nov 21, 2019 10:30 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Which shape
Replies: 4
Views: 15

Which shape

How do you determine if the shape formed will be polar or non polar? For example if a molecule can be either cis or trans(CCl2H2) how do you tell if you are asked to determine if the molecule is polar or non polar?
by annikaying
Thu Nov 21, 2019 10:28 am
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: Strongest force
Replies: 6
Views: 19

Strongest force

Which intermolecular force is strongest? I though it was hydrogen bonding, but now I'm wondering if intermolecular forces involving ions are stronger.
by annikaying
Thu Nov 21, 2019 10:27 am
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: Forces
Replies: 3
Views: 15

Forces

Are induced dipole forces the same as London dispersion forces? Also does induced dipole only occur between a polar and non polar molecule?
by annikaying
Wed Nov 13, 2019 5:17 pm
Forum: Bond Lengths & Energies
Topic: Bond lengths in molecules
Replies: 7
Views: 29

Re: Bond lengths in molecules

The more bonds there are (triple versus single) the shorter the bond is. This is because there are more e being shared and thus both atoms are pulled in closer together.
by annikaying
Wed Nov 13, 2019 5:14 pm
Forum: Balancing Chemical Reactions
Topic: Fractions
Replies: 20
Views: 122

Re: Fractions

I would convert it to an integer as the TAs always change it and they are the ones that grade the tests and homework.
by annikaying
Wed Nov 13, 2019 5:12 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge
Replies: 7
Views: 26

Re: Formal Charge

formal charge = V - (L + B/2)
V - valence e
L - e in lone pairs
B - e in bonded pairs
This will give you the formal charge of one atom in a molecule. To find the formal charge add of the formal charges of all the individual atoms.
by annikaying
Wed Nov 13, 2019 5:09 pm
Forum: Empirical & Molecular Formulas
Topic: empirical = molecular?
Replies: 15
Views: 103

Re: empirical = molecular?

If the molar mass given is equal to that of the empirical formula then the chemical formula found is both the empirical and molecular formula.
by annikaying
Wed Nov 13, 2019 5:08 pm
Forum: SI Units, Unit Conversions
Topic: Memorizing Conversions
Replies: 23
Views: 126

Re: Memorizing Conversions

Everything that is needed should be provided. However, knowing the conversions definitely helps with exams.
by annikaying
Wed Nov 13, 2019 5:06 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VESPR Model of H2O
Replies: 12
Views: 44

Re: VESPR Model of H2O

H2O is bent. I'm assuming we will cover molecular shapes with lone pairs sometime in the next week.
by annikaying
Sun Nov 03, 2019 9:17 am
Forum: Resonance Structures
Topic: "Equivalent" resonance structures
Replies: 2
Views: 19

Re: "Equivalent" resonance structures

A resonance structure only has a difference in the placement of double and triple bonds. I think formal charges would determine which of the resonance structures is most likely, but you only need to look at bonds to see if there is resonance.
by annikaying
Sun Nov 03, 2019 9:14 am
Forum: SI Units, Unit Conversions
Topic: midterm 1
Replies: 5
Views: 34

midterm 1

Does anyone know if Lewis acids and bases will be on the first midterm? And which topics are going to be covered?
by annikaying
Sun Nov 03, 2019 9:12 am
Forum: Lewis Structures
Topic: Exceptions to octet rule
Replies: 4
Views: 19

Exceptions to octet rule

Which elements can break the octet rule when forming lewis dot structures and is it likely or just when necessary?
by annikaying
Sun Nov 03, 2019 9:11 am
Forum: Lewis Structures
Topic: Lowest Energy
Replies: 2
Views: 14

Lowest Energy

How do you determine the lowest energy lewis structure? For example some structures break the octet rule to get the lowest energy structure. Does that mean formal charges are more important than the octet rule in determining the lowest energy?
by annikaying
Sun Nov 03, 2019 9:08 am
Forum: Trends in The Periodic Table
Topic: Exceptions
Replies: 4
Views: 18

Exceptions

What are some of the exceptions to periodic trends? For example O has a lower ionization energy than N.
by annikaying
Wed Oct 23, 2019 4:20 pm
Forum: Ionic & Covalent Bonds
Topic: Ionic vs covalent
Replies: 8
Views: 221

Re: Ionic vs covalent

You can look at the electronegativity difference to determine if the bond is ionic or covalent but typically you can just go off of whether or not the two atoms are both nonmetal (which gives a covalent bond) or if they are a nonmetal with a metal (which gives an ionic bond).
by annikaying
Wed Oct 23, 2019 4:17 pm
Forum: Octet Exceptions
Topic: Max number of valence e
Replies: 6
Views: 35

Max number of valence e

What is the max number of valence e an atom can have? I know there is the octet rule but is that just where the atom is most stable?
by annikaying
Wed Oct 23, 2019 4:15 pm
Forum: Lewis Structures
Topic: Ion lewis structure
Replies: 9
Views: 38

Ion lewis structure

When drawing a lewis dot structure does it matter where in the molecule you put the added e ? For example when you have BrO- does it matter where that extra electron is added into the structure?
by annikaying
Wed Oct 23, 2019 4:13 pm
Forum: Ionic & Covalent Bonds
Topic: Ionic Compounds
Replies: 6
Views: 74

Ionic Compounds

Are ionic compounds actually bonded and if so how? I understand e are being transferred but how does this transfer differ from a covalent bond in which they are shared?
by annikaying
Wed Oct 23, 2019 4:11 pm
Forum: Lewis Structures
Topic: Valence e in d block
Replies: 5
Views: 21

Valence e in d block

How do you count the valence e in the d block? For example how many valence e does Zn have and why?
by annikaying
Sat Oct 19, 2019 3:53 pm
Forum: Limiting Reactant Calculations
Topic: Test 1 Calculator
Replies: 6
Views: 74

Re: Test 1 Calculator

You can cheat if you have a graphing calculator as you can store equations and notes in it.
by annikaying
Sat Oct 19, 2019 3:52 pm
Forum: Molarity, Solutions, Dilutions
Topic: What is Molarity?
Replies: 11
Views: 66

Re: What is Molarity?

Molarity is the ratio of the moles of a solute to the liters of the entire solution. This is used to measure the concentration of a specific amount of a substance to the entire solution.
by annikaying
Sat Oct 19, 2019 3:49 pm
Forum: SI Units, Unit Conversions
Topic: midterm/final
Replies: 4
Views: 44

midterm/final

Does anyone know if the midterm/final is going to be more about concepts or calculations? For example which is more likely an essay question or a calculation?
by annikaying
Sat Oct 19, 2019 3:47 pm
Forum: Properties of Electrons
Topic: Angstrom Conversion
Replies: 12
Views: 90

Re: Angstrom Conversion

An angstrom is equivalent to 1 x 10^-10 m. I personally compare the values of 10^x to see which way the decimal point needs to move to be in angstroms.
by annikaying
Sat Oct 19, 2019 3:43 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Memorizing electron configuration
Replies: 3
Views: 27

Memorizing electron configuration

Are there any tricks to memorizing which orbital electrons fill up first?
by annikaying
Wed Oct 09, 2019 3:36 pm
Forum: Photoelectric Effect
Topic: Threshold energy
Replies: 6
Views: 40

Re: Threshold energy

The threshold energy depends on the type of element as different elements have different properties.
by annikaying
Wed Oct 09, 2019 3:33 pm
Forum: Properties of Electrons
Topic: Polar vs Non polar
Replies: 15
Views: 613

Re: Polar vs Non polar

Polar molecules have an uneven hold on the electrons whereas in non polar molecules the electrons are shared equally or mostly equally. You can tell just by looking at the electronegativity differences of the certain elements.
by annikaying
Wed Oct 09, 2019 3:30 pm
Forum: Photoelectric Effect
Topic: Atomic Spectra [ENDORSED]
Replies: 3
Views: 39

Atomic Spectra [ENDORSED]

Why is the line spectrum grouped in specific parts? I know it has to do with the specific releases of energy but how exactly to the two correlate?
by annikaying
Wed Oct 09, 2019 3:29 pm
Forum: Properties of Electrons
Topic: Energy
Replies: 6
Views: 42

Energy

Can an atom only take in energy in quanta amounts? I know it is released as such but if struck with light will it only move up an energy level if that specific energy requirement is met? And if so does that mean it would need a second energy requirement to move up another level?
by annikaying
Wed Oct 09, 2019 3:26 pm
Forum: Properties of Electrons
Topic: Energy Levels
Replies: 8
Views: 49

Energy Levels

I was wondering if when an electron drops two energy levels does that mean that two photons are released or is it just a photon with more energy?
by annikaying
Thu Oct 03, 2019 12:42 pm
Forum: Balancing Chemical Reactions
Topic: Products of combustion reactions
Replies: 7
Views: 45

Re: Products of combustion reactions

The products always include CO2 and H2O but there can also be additional products depending on what is being combusted. For example the combustion of caffeine (C8H10N4O2) also produces the product NO2 alongside CO2 and H2O.
by annikaying
Thu Oct 03, 2019 12:38 pm
Forum: Molarity, Solutions, Dilutions
Topic: Empirical and Molecular Formulas
Replies: 13
Views: 95

Re: Empirical and Molecular Formulas

If you are given a formula and a given mass you can calculate the molar mass of the compound and see if the two masses are equal. If they are equal then the given formula is empirical. If not, then it is a molecular formula. You also may be able to tell by checking if the ratios are all in their sma...
by annikaying
Thu Oct 03, 2019 12:34 pm
Forum: Empirical & Molecular Formulas
Topic: Finding a reactant from given products
Replies: 2
Views: 50

Finding a reactant from given products

I know in some of the hw problems there are examples in which the masses of the products are given and from there you have to find out the empirical and molecular formulas of the reactant. To solve this you eventually have to take a ratio from the atoms in the product to the reactant (ex. 1 mol H/2 ...
by annikaying
Thu Oct 03, 2019 12:28 pm
Forum: Student Social/Study Group
Topic: Final Jitters
Replies: 63
Views: 18531

Re: Final Jitters

Doing practice problems usually helps me for tests. I will also say that jitters before the first test are definitely worse than following tests as you have less of an idea of what to expect. I would just prepare as best as you can and use your experience with the first test to help you study for fo...
by annikaying
Tue Oct 01, 2019 12:17 pm
Forum: Empirical & Molecular Formulas
Topic: Mass Percent Composition
Replies: 5
Views: 46

Mass Percent Composition

Is it necessary to imagine that you have 100g of a molecule when trying to figure out the empirical and molecular formulas? You are trying to convert everything to moles, so if you are originally given grams of the different chemicals in the molecule, could you not skip the conversion to mass percen...

Go to advanced search