Search found 50 matches

by PGao_1B
Wed Dec 04, 2019 6:19 pm
Forum: Student Social/Study Group
Topic: Preparing for the final
Replies: 25
Views: 160

Re: Preparing for the final

Try to go to as many TA review sessions as possible, and practice as many problems as you possibly can.
by PGao_1B
Wed Dec 04, 2019 6:16 pm
Forum: Bronsted Acids & Bases
Topic: CaO
Replies: 10
Views: 54

Re: CaO

CaO is a strong base because it fully dissociates to give ions in solution.
by PGao_1B
Wed Dec 04, 2019 6:14 pm
Forum: Lewis Acids & Bases
Topic: diff b/w lewis acid and base
Replies: 12
Views: 81

Re: diff b/w lewis acid and base

Lewis acids are electron - pair acceptors and Lewis bases are electron - pair donors.
by PGao_1B
Wed Dec 04, 2019 6:12 pm
Forum: Lewis Acids & Bases
Topic: Definition
Replies: 7
Views: 41

Re: Definition

The definitions of a Lewis acid and base that Dr. Lavelle wants are electron - pair acceptor and electron - pair donor, respectively.
by PGao_1B
Wed Dec 04, 2019 6:09 pm
Forum: Lewis Acids & Bases
Topic: Oxoacids
Replies: 6
Views: 38

Re: Oxoacids

Oxoacids are acids that contain oxygen. To be more specific, oxoacids are acids that contain oxygen, contain at least one other element, have at least one hydrogen atom bonded to oxygen, and form an ion by the loss of one or more protons in solution.
by PGao_1B
Sun Dec 01, 2019 11:55 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Cis vs Trans
Replies: 21
Views: 140

Re: Cis vs Trans

The difference between the terms cis and trans is that cis means polar and trans means nonpolar.
by PGao_1B
Sun Dec 01, 2019 11:50 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: brackets
Replies: 13
Views: 59

Re: brackets

What the brackets signify when they are around the compound is a coordination compound.
by PGao_1B
Sun Dec 01, 2019 11:48 pm
Forum: Naming
Topic: Final Exam?
Replies: 20
Views: 128

Re: Final Exam?

The final exam is cumulative, so we can just base off what we need to know by using the outlines.
by PGao_1B
Sun Dec 01, 2019 11:47 pm
Forum: Naming
Topic: Roman Numeral
Replies: 13
Views: 65

Re: Roman Numeral

The roman numerals represent the oxidation number of the metal ion.
by PGao_1B
Sun Dec 01, 2019 11:33 pm
Forum: Naming
Topic: Oxidation
Replies: 14
Views: 104

Re: Oxidation

An oxidation number is a number associated with the charge that an atom would have if the compound was composed of ions.
by PGao_1B
Sun Nov 24, 2019 11:44 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Drawing molecules
Replies: 7
Views: 46

Re: Drawing molecules

I personally don't think we will ever have to draw molecules in such a way that was similar to what was on the test - it is most likely for a future chemistry class (nonetheless, you will be better off safe than sorry if you prepared so).
by PGao_1B
Sun Nov 24, 2019 11:39 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Lone Pairs on Cenrtral Atom
Replies: 11
Views: 40

Re: Lone Pairs on Cenrtral Atom

Lone pairs around a central atom affect the bond angles in a molecule by decreasing them due to the repulsion between electrons.
by PGao_1B
Sun Nov 24, 2019 11:34 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: AXE Format
Replies: 34
Views: 121

Re: AXE Format

Whenever there's only one X or one E, we do not have to write a subscript of "1" - we just write "X" and "E," respectively.
by PGao_1B
Sun Nov 24, 2019 11:31 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Final
Replies: 10
Views: 45

Re: Final

Yes, the final is cumulative.
by PGao_1B
Sun Nov 24, 2019 11:30 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: melting point
Replies: 8
Views: 36

Re: melting point

If one bond were to be broken, what happens to the melting point is that it decreases.
by PGao_1B
Sat Nov 16, 2019 4:40 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Polar vs. Nonpolar
Replies: 12
Views: 79

Re: Polar vs. Nonpolar

It is generally not recommended to look at a molecule's geometry / shape when determining if it's polar or non polar. It is best to use the VSEPR model and calculate the actual dipole moments to see if they add up to a net value of 0. If they do, the molecule is non polar, and if they do not, the mo...
by PGao_1B
Sat Nov 16, 2019 4:32 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: All VSEPR structures or just ones from class?
Replies: 11
Views: 64

Re: All VSEPR structures or just ones from class?

We should know all of the ones on the chart instead of only the ones Dr. Lavelle went over in class for Test 2. It's better to be safe than sorry.
by PGao_1B
Sat Nov 16, 2019 4:30 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Determining if a molecule is polar or non polar
Replies: 9
Views: 51

Re: Determining if a molecule is polar or non polar

When determining if a molecule is polar or non polar on the test, it is not expected of us to know the electronegativity values of the elements in the given molecules. Just know the periodic trends for electronegativity and you should be fine.
by PGao_1B
Sat Nov 16, 2019 4:25 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: How to study for VSEPR?
Replies: 9
Views: 84

Re: How to study for VSEPR?

In terms of studying for VSEPR for Test 2, just do as much practice problems as you can - the more the better. In terms of "good" practice problem suggestions, start by completing all the practice problems in the Molecular Shape and Structure unit outline (although only 5 are required for ...
by PGao_1B
Sat Nov 16, 2019 4:17 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: test 2
Replies: 13
Views: 78

Re: test 2

We do not have to know hybridization for Test 2 (as stated by Dr. Lavelle in class). However, pi and sigma bonds will be on Test 2, for which Dr. Lavelle will cover those topics in class on Monday. Essentially, Test 2 will cover all the material covered in class up until Monday after the midterm exam.
by PGao_1B
Sat Nov 09, 2019 12:04 am
Forum: Resonance Structures
Topic: Resonance Structures
Replies: 18
Views: 109

Re: Resonance Structures

Resonance structures are two or more forms of a molecule where the chemical connectivity is the same but the electrons are distributed differently around the structure.
by PGao_1B
Sat Nov 09, 2019 12:03 am
Forum: Electronegativity
Topic: Trend of Electronegativity
Replies: 22
Views: 102

Re: Trend of Electronegativity

Electronegativities generally increase from left to right across a period. This is due to an increase in nuclear charge. Electronegativities generally decrease from top to bottom within a group due to the larger atomic size.
by PGao_1B
Sat Nov 09, 2019 12:02 am
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge Equation?
Replies: 12
Views: 48

Re: Formal Charge Equation?

Yes, both depend on how you count the shared bond. The first equation treats the number of bonds as how many "lines" you draw as bonds, while the second equation treats the number of bonds as the amount of valence electrons that are shared in total between an atom and another respective at...
by PGao_1B
Fri Nov 08, 2019 11:55 pm
Forum: Formal Charge and Oxidation Numbers
Topic: central atom
Replies: 21
Views: 104

Re: central atom

Yes, we want to make it so that the central atom has a formal charge of zero, or as close to zero as it can get - that would be the ideal situation.
by PGao_1B
Fri Nov 08, 2019 11:53 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Showing Work
Replies: 6
Views: 42

Re: Showing Work

We should write out the entire equation for formal charge on the midterm instead of just calculating it in our head and writing the formal charge by the element because not only will writing out the entire equation for formal charge make it easier to organize both your thoughts and work, but it will...
by PGao_1B
Thu Oct 31, 2019 5:47 pm
Forum: Lewis Structures
Topic: valence electrons
Replies: 4
Views: 54

Re: valence electrons

The trends for valence electrons are as follows: in a period, the number of valence electrons increases as we move from left to right side and in a group, the number of valence electrons remains the same.
by PGao_1B
Thu Oct 31, 2019 5:44 pm
Forum: Lewis Structures
Topic: Drawing lewis structures
Replies: 8
Views: 52

Re: Drawing lewis structures

Since this topic has not been covered in - depth yet in the lectures, you shouldn't worry too much about it. But, in general, it is better to be safe than sorry, so when drawing Lewis structures on tests, you should angle the bonds in the correct ways.
by PGao_1B
Thu Oct 31, 2019 5:39 pm
Forum: Ionic & Covalent Bonds
Topic: What is the Octet Rule?
Replies: 5
Views: 29

Re: What is the Octet Rule?

The concept of the octet rule is that elements tend to bond in such a way that each atom has eight electrons in its valence shell, giving it the same electronic configuration as a noble gas.
by PGao_1B
Thu Oct 31, 2019 5:37 pm
Forum: Ionic & Covalent Bonds
Topic: Lewis structure
Replies: 3
Views: 30

Re: Lewis structure

When we draw the Lewis structure, we know which atom is in the middle in that usually the central atom will be the one that has the most unpaired valence electrons - usually it is also the least electronegative.
by PGao_1B
Thu Oct 31, 2019 5:33 pm
Forum: Ionic & Covalent Bonds
Topic: Homework for Week 5
Replies: 8
Views: 55

Re: Homework for Week 5

For homework this week, we can do either quantum to review or chemical bonding. I personally did chemical bonding for homework, but it doesn't really matter to your designated TA as long as the material has been recently covered in lectures.
by PGao_1B
Sat Oct 26, 2019 10:45 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Shorthand Notation
Replies: 4
Views: 23

Re: Shorthand Notation

For both the midterm and future tests, we should write the whole electron configuration instead of the shorthand notation because not only will you be more safe than sorry, you will gain better understanding of how to write electron configurations accurately.
by PGao_1B
Sat Oct 26, 2019 10:35 pm
Forum: Quantum Numbers and The H-Atom
Topic: ionization energy and electron affinty
Replies: 3
Views: 29

Re: ionization energy and electron affinty

The difference between electron affinity and ionization energy is that electron affinity gives the amount of energy released when an atom gains an electron, and ionization energy is the amount of energy required to remove an electron from an atom.
by PGao_1B
Sat Oct 26, 2019 10:31 pm
Forum: Quantum Numbers and The H-Atom
Topic: Quantum number m
Replies: 3
Views: 24

Re: Quantum number m

The magnetic quantum number m l determines the number of orbitals and their orientation within a subshell. Consequently, its value depends on the orbital angular momentum quantum number l. Given a certain l, m l is an interval ranging from –l to +l, so it can be zero, a negative integer, or a positi...
by PGao_1B
Sat Oct 26, 2019 10:21 pm
Forum: Quantum Numbers and The H-Atom
Topic: Quantum Numbers
Replies: 7
Views: 72

Re: Quantum Numbers

Electron spin, s, has only two possible values: and , representing whether the electron is "spin - up" or "spin - down," respectively. Electron spin determines if an atom will or will not generate a magnetic field.
by PGao_1B
Sat Oct 26, 2019 10:08 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: oribital numbers
Replies: 7
Views: 38

Re: oribital numbers

The s subshell has 1 orbital that can hold up to 2 electrons, the p subshell has 3 orbitals that can hold up to 6 electrons, the d subshell has 5 orbitals that hold up to 10 electrons, and the f subshell has 7 orbitals with 14 electrons.
by PGao_1B
Sun Oct 20, 2019 2:32 pm
Forum: Photoelectric Effect
Topic: When energy is equal to work function
Replies: 9
Views: 86

Re: When energy is equal to work function

In the photoelectric effect, if the energy of the photon is equal to that of the work function (i.e. no kinetic energy), what would happen is that the energy threshold will be met and the electron will be ejected.
by PGao_1B
Sun Oct 20, 2019 2:29 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Frequencies
Replies: 7
Views: 51

Re: Frequencies

In general, no memorization is required to solve a problem - everything you need will be given on the formula sheet. However, in this case, knowing the region of the frequency / wavelength of the electromagnetic spectrum will certainly be beneficial for you, both in terms of your chemistry knowledge...
by PGao_1B
Sun Oct 20, 2019 2:16 pm
Forum: DeBroglie Equation
Topic: Mass of electron and photon
Replies: 5
Views: 46

Re: Mass of electron and photon

In general, no memorization is required. All the information you will need to solve a problem will be given on the formula sheet.
by PGao_1B
Sun Oct 20, 2019 2:09 pm
Forum: Einstein Equation
Topic: unit of energy
Replies: 7
Views: 269

Re: unit of energy

keV is the abbreviation for kiloelectron volts, a unit of energy equivalent to the kinetic energy gained by an electron falling through a potential of 1 volt.
by PGao_1B
Sun Oct 20, 2019 2:07 pm
Forum: Einstein Equation
Topic: Units for E [ENDORSED]
Replies: 4
Views: 60

Re: Units for E [ENDORSED]

The unit for E is always implied as being J / photons, but if you want to convert to J / atoms, you must use Avogadro's number.
by PGao_1B
Sun Oct 13, 2019 10:46 pm
Forum: Einstein Equation
Topic: Final Grade
Replies: 5
Views: 4027

Re: Final Grade

Our final grade is calculated on a point system (specifically 500 points). Take a peak at the syllabus posted for more information.
by PGao_1B
Sun Oct 13, 2019 10:35 pm
Forum: Trends in The Periodic Table
Topic: Atomic Radius
Replies: 16
Views: 145

Re: Atomic Radius

The effect shielding has on the atomic radius is that it prevents outer electrons from being attracted to the nucleus. Thus, since they are loosely held, the resulting atomic radius is large.
by PGao_1B
Sun Oct 13, 2019 10:24 pm
Forum: Trends in The Periodic Table
Topic: Element Names
Replies: 8
Views: 444

Re: Element Names

In general, no memorization is required for tests, but you should be familiar with the majority of the elements listed on the periodic table.
by PGao_1B
Sun Oct 13, 2019 10:20 pm
Forum: Trends in The Periodic Table
Topic: electronegativity
Replies: 10
Views: 364

Re: electronegativity

Electronegativity is a chemical property that describes the tendency of an atom to attract a shared pair of electrons toward itself. Electronegativities generally increase from left to right across a period and generally decrease from top to bottom within a group.
by PGao_1B
Sun Oct 13, 2019 10:11 pm
Forum: Einstein Equation
Topic: E=hv
Replies: 5
Views: 44

Re: E=hv

In this case, the equation says that the energy of a particle of light is proportional to its frequency by a constant factor. Therefore, this equation can be used to calculate the energy required to remove an electron.
by PGao_1B
Thu Oct 03, 2019 9:22 am
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Formula Units
Replies: 6
Views: 74

Re: Formula Units

Formula units are empirical formulas of any ionic or covalent network solid compound used as an independent entity for stoichiometric calculations. It is the lowest whole number ratio of ions represented in an ionic compound. There are 6.022 * 10 ^ {23} (Avogadro's number) formula units in 1 mole of...
by PGao_1B
Thu Oct 03, 2019 9:12 am
Forum: Molarity, Solutions, Dilutions
Topic: Molarity
Replies: 9
Views: 76

Re: Molarity

Molarity represents the concentration of a solution (specifically the number of moles of solute per liter of solution). You would need to calculate molarity in a wide variety of various situations, including calculating the moles of a solution, calculating the volume of a solution, calculating the m...
by PGao_1B
Thu Oct 03, 2019 9:03 am
Forum: Balancing Chemical Reactions
Topic: Unequal coefficients
Replies: 7
Views: 69

Re: Unequal coefficients

No, we cannot use fractions to balance chemical equations. We can use fractions in the process of balancing chemical equations, but in the end we should obtain whole number coefficients by multiplying each and every coefficient by the denominators of each and every fraction coefficient.
by PGao_1B
Thu Oct 03, 2019 8:54 am
Forum: Balancing Chemical Reactions
Topic: balancing reaction law
Replies: 4
Views: 284

Re: balancing reaction law

In chemical reactions atoms are not created or destroyed. Total mass before = total mass after. The law of conservation of mass states that the total atoms of reactants = the total atoms of products, so you cannot add reactants or products to a chemical equation.
by PGao_1B
Thu Oct 03, 2019 8:49 am
Forum: Empirical & Molecular Formulas
Topic: Empirical Formula Purpose
Replies: 13
Views: 143

Re: Empirical Formula Purpose

The empirical formula of a compound gives the simplest whole - number ratio between the numbers of atoms of all the elements present in the compound.

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