Search found 37 matches

by 305392242
Thu Nov 26, 2020 1:58 pm
Forum: Trends in The Periodic Table
Topic: atomic radius of anions
Replies: 4
Views: 23

Re: atomic radius of anions

In neutral state, Bromine is smaller than Na due to it's location on the far right of the periodic table. However, Br- is an anion. Anions have bigger ionic radii than their corresponding neutral atoms.
by 305392242
Thu Nov 26, 2020 1:48 pm
Forum: Properties of Light
Topic: Momentum of light
Replies: 4
Views: 37

Re: Momentum of light

Correct, photons do not have mass but they still have a momentum which allows it to carry Energy. An object can have momentum without mas if it is a wave. A wave transports momentum via its waving motion and not by physically transporting an object with mass.
by 305392242
Thu Nov 26, 2020 1:42 pm
Forum: Sigma & Pi Bonds
Topic: Carbon bonds
Replies: 2
Views: 11

Carbon bonds

If Carbon only has 2 unpaired electrons, why does it form 4 bonds?
How does this ability to form 4 bonds make organic molecules so special?
by 305392242
Thu Nov 26, 2020 1:38 pm
Forum: Electronegativity
Topic: Periodic Table Trend
Replies: 27
Views: 250

Re: Periodic Table Trend

Ionization energy and electronegativity decrease down a group. Ionization energy and electronegativity also increase across a period. What helps me remember this is to remember that fluorine is the smallest and most electronegative atom, if you look at the periodic table you will see that it is at t...
by 305392242
Thu Nov 26, 2020 1:36 pm
Forum: Electronegativity
Topic: What determine bond strength?
Replies: 4
Views: 19

What determine bond strength?

In determining bond strength, which characteristic take priority? Is it size of atom (and thus bond length) or electronegativity of an atom in a molecule? CF4 has a very strong bond because of the small size of the fluorine atom and the short bond lengths. The textbook also says, "note that ele...
by 305392242
Thu Nov 26, 2020 1:33 pm
Forum: Electronegativity
Topic: Electronegativity and Bond Strength
Replies: 3
Views: 1704

Re: Electronegativity and Bond Strength

To elaborate on the statement "note that electronegativity and polarity arguments would predict the C--F bond to be the weakest", because Fluorine is highly electronegative, then the bond is weak because F is strongly attracting the electron which belong to Carbon. Thus it would be easier ...
by 305392242
Thu Nov 26, 2020 1:25 pm
Forum: Electronegativity
Topic: Partial vs Formal charge
Replies: 8
Views: 32

Re: Partial vs Formal charge

The formal charge of an atom indicates the gain or loss of an electron while forming a covalent bond. To determine the formal charge I use the following rationale: Formal Charge = Valence electrons of neutral atom - (Shared electrons/2 - lone pair electrons)
by 305392242
Thu Nov 26, 2020 12:56 pm
Forum: Electronegativity
Topic: Polarity of Molecules
Replies: 6
Views: 22

Re: Polarity of Molecules

When looking at the lewis structure, polarity can be determined from the symmetry of the lewis structure. The more symmetrical the appearance of the lewis structure is, the more likely it is to be polar. Also, knowing the electronegativity of each element (from the trends) is a consistent reliable w...
by 305392242
Mon Nov 16, 2020 5:15 pm
Forum: Electronegativity
Topic: Partial vs Formal charge
Replies: 8
Views: 32

Re: Partial vs Formal charge

The formal charge is the charge that an atom appears to have when we count the electrons according to certain arbitrary rules. Formal charge is an integer property that is essential for the correct valence representation of a molecule.

The partial charge is the charge that the atom really has.
by 305392242
Mon Nov 16, 2020 5:12 pm
Forum: Electronegativity
Topic: Tips on remembering trend
Replies: 5
Views: 32

Re: Tips on remembering trend

I remember that helium is the smallest atom and that francium is the largest. Because there are added shells with each descending row, I know that as I go down, atoms get larger. Also, I know that noble gases are the most stable elements and thus they are more tightly held..thus I remember that as I...
by 305392242
Mon Nov 16, 2020 5:06 pm
Forum: Electronegativity
Topic: Relationship between Dispersion and Electronegativity
Replies: 6
Views: 26

Re: Relationship between Dispersion and Electronegativity

Electronegativity determines the intramolecular forces (the forces that hold atoms in place). Electronegativity will determine whether the molecule is polar or non-polar, in other words, the chemical bond. The intramolecular forces affect the nature of the INTERmolecular forces (forces that hold mol...
by 305392242
Mon Nov 16, 2020 4:55 pm
Forum: Electronegativity
Topic: polar vs nonpolar
Replies: 13
Views: 42

Re: polar vs nonpolar

The difference in electronegativity needs to be between 0.5 and 1.6 to be considered polar!
by 305392242
Mon Nov 16, 2020 4:53 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Oxidation Sapling 9
Replies: 6
Views: 35

Re: Oxidation Sapling 9

Sum of oxidation numbers for a neutral compound is always 0. Sum of oxidation numbers for a polyatomic ion is the ion charge. When calculating oxidation numbers, remember that group 1A elements are always +1, Group 2A are always +2, Halogens are usually -1 (positive with oxygen). Hydrogen is always ...
by 305392242
Sun Nov 08, 2020 12:30 pm
Forum: Properties of Electrons
Topic: Understanding energy transitions
Replies: 4
Views: 30

Re: Understanding energy transitions

When the energy is higher, the wavelength is shorter. This relationship can be observed from the energy equation. n=6 to n=1 has a greater energy emission than n=6 to n=5, therefore the wavelength would be shorter.
by 305392242
Sun Nov 08, 2020 12:28 pm
Forum: Properties of Electrons
Topic: Electrons as Waves and Particles
Replies: 4
Views: 35

Re: Electrons as Waves and Particles

All electrons behave wave-like and particle-like. Larger objects are not affected by waves because they are so massive, and they are also more predictable than small objects. These principles are derived from the Heisenberg Uncertainty Principle.
by 305392242
Sun Nov 08, 2020 12:19 pm
Forum: Properties of Electrons
Topic: intensity vs energy
Replies: 25
Views: 128

Re: intensity vs energy

The intensity of light is dependent on the amount of photons. However the intensity does not determine on the overall energy.
The photoelectric effect shows that frquency has effect on the ejection of electrons.
by 305392242
Sun Nov 08, 2020 12:15 pm
Forum: Properties of Electrons
Topic: Energy needed to remove an electron
Replies: 3
Views: 32

Re: Energy needed to remove an electron

I conceptualize it using this equation: https://www.google.com/imgres?imgurl=https%3A%2F%2Fslideplayer.com%2Fslide%2F3866354%2F13%2Fimages%2F8%2FThe%2Bphotoelectric%2Bequation.jpg&imgrefurl=https%3A%2F%2Fslideplayer.com%2Fslide%2F3866354%2F&tbnid=YQrn8DIi441WVM&vet=12ahUKEwijxoaQ4fPsAhVh...
by 305392242
Sun Nov 08, 2020 12:10 pm
Forum: Properties of Electrons
Topic: Electron Spin
Replies: 7
Views: 54

Re: Electron Spin

Technically, electrons have an angular momentul which is a type of momentum possessed by rotating objects. This attributes the spinning nature and it is is a fundamental characteristic of electrons.
by 305392242
Sun Nov 08, 2020 12:08 pm
Forum: Ionic & Covalent Bonds
Topic: Resonance and Bond Order
Replies: 2
Views: 40

Re: Resonance and Bond Order

Bond length is defined as the distance between the centers of two covalently bonded atoms. The length of the bond is determined by the number of bonded electrons (the bond order). The higher the bond order, the stronger the pull between the two atoms and the shorter the bond length.
by 305392242
Sun Nov 08, 2020 12:05 pm
Forum: Ionic & Covalent Bonds
Topic: Electronegativity
Replies: 16
Views: 82

Re: Electronegativity

Fluorine is the most electronegative element because it has 5 electrons in it's 2P shell. Because it only requires 1 electron to reach stability, it is highly reactive.
by 305392242
Sun Nov 08, 2020 12:03 pm
Forum: Ionic & Covalent Bonds
Topic: Extra Valence Electrons
Replies: 10
Views: 46

Re: Extra Valence Electrons

Those elements are just exceptions to the octet rule.
by 305392242
Sun Nov 08, 2020 11:57 am
Forum: Ionic & Covalent Bonds
Topic: Electron Affinity vs. Electronegativity
Replies: 12
Views: 54

Re: Electron Affinity vs. Electronegativity

Electronegativity is the ability of an atom to attract electrons from outside, it is a qualitative property, measured from Pauling units, and it's applied for a single atom. Electron affinity is the amount of energy released when a neutral atom or molecule gains an electron from outside, it is a qua...
by 305392242
Sun Nov 08, 2020 11:50 am
Forum: Properties of Light
Topic: rydberg's constant
Replies: 10
Views: 68

Re: rydberg's constant

It depends on which equation is being used.

R = 3.28984 x10^15 Hz is used for the Rydberg equation with frequency, or v = R(1/n1^2 - 1/n2^2).
R = 1.097x10^7 m is used for the Rydberg equation with wavelength, or 1/wavelength = R(1/n1^2 - 1/n2^2).
by 305392242
Sun Nov 08, 2020 11:48 am
Forum: Properties of Light
Topic: Equation clarifications
Replies: 4
Views: 30

Re: Equation clarifications

The equation is actually E=hc/λ where λ is wavelength.
However we can extract the equation c/λ = v where v is frequency and c is the speed of light.
by 305392242
Sun Nov 08, 2020 11:38 am
Forum: Properties of Light
Topic: Which model of light is atomic spectroscopy?
Replies: 8
Views: 54

Re: Which model of light is atomic spectroscopy?

The particle model is used for atomic spectroscopy
by 305392242
Sun Nov 08, 2020 11:32 am
Forum: Properties of Light
Topic: Midterm Question
Replies: 11
Views: 142

Re: Midterm Question

The fundamentals until 1D. These topics are on the chemistry website.
by 305392242
Sun Nov 08, 2020 11:31 am
Forum: Properties of Light
Topic: Is c always the speed of light?
Replies: 70
Views: 236

Re: Is c always the speed of light?

In this class, you can always count on c being the speed of light.
by 305392242
Sun Nov 08, 2020 11:30 am
Forum: Properties of Light
Topic: How to remember what v is in equations
Replies: 46
Views: 138

Re: How to remember what v is in equations

Typically nu denotes frequency, which looks like an italicized v. A diligent way to confirm whether or not it is velocity or frequency is to check the units! Velocity is in m/s whereas frequency is in Hz. Typically the speed of light is denoted with "c"
by 305392242
Sun Nov 08, 2020 11:28 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Subshell Definition
Replies: 9
Views: 54

Re: Subshell Definition

This infograpgic was helpul to me when differentiating the terms: https://pediaa.com/wp-content/uploads/2 ... ummary.png
by 305392242
Sun Nov 08, 2020 11:25 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Orbital energy
Replies: 5
Views: 42

Re: Orbital energy

4s orbitals are said to have a lower energy than the 3d orbitals because they are filled first.
by 305392242
Sun Nov 08, 2020 11:22 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Orbital vs Subshell
Replies: 7
Views: 67

Re: Orbital vs Subshell

Shells are composed of electrons that share the same principal quantum number. Whereas subshells are composed of electrons that share the same angular momentum quantum number whereas orbitals are composed of electrons that are in the same energy level but have different spins. This infographic helps...
by 305392242
Sun Nov 08, 2020 11:19 am
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student [ENDORSED]
Replies: 221
Views: 116128

Re: Advice from a Medical Student [ENDORSED]

Thanks so much for your advice! I will definitely keep my notes handy as I go through my UCLA journey. Can you tell us a little bit more about your gap year? What types of clubs/ internships/ research opportunities/ etc. you were involved in that helped strengthen your medical school application? M...
by 305392242
Sun Oct 11, 2020 11:13 am
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student - Part II [ENDORSED]
Replies: 188
Views: 14308

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

Thank you so much for dedicating time to writing this. It was so incredibly helpful to me.
by 305392242
Sun Oct 11, 2020 11:09 am
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Calculating number of moles of an element
Replies: 10
Views: 57

Re: Calculating number of moles of an element

100g is a tool to help conceptualize the elemental proportions of a molecule to equal 100%. It's an arbitrary number that always works in those problems.
by 305392242
Sun Oct 11, 2020 11:07 am
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8208
Views: 1433848

Re: Post All Chemistry Jokes Here

Why do chemists like nitrates so much?
They're cheaper than day rates.

I asked the guy sitting next to me if he had any Sodium Hypobromite…
He said NaBrO
by 305392242
Sun Oct 11, 2020 11:04 am
Forum: Student Social/Study Group
Topic: Final Jitters
Replies: 178
Views: 34469

Re: Final Jitters

I allocate a set time to review my notes and perhaps for practice problems, but not too much time at once. If I overspend my time all at once for studying I am overwhelmed. So, maybe 30 min of skimming over my notes, and then 20 minutes doing some problems. That is one session. Then, I take breaks t...
by 305392242
Sun Oct 11, 2020 10:59 am
Forum: Molarity, Solutions, Dilutions
Topic: Formulas involved in Determining Solution Concentration
Replies: 8
Views: 55

Re: Formulas involved in Determining Solution Concentration

When completing problems on solutions, I am not quick to apply the formulas in which you described (M=n/v or M Initial V final = M final V final) When it comes to solutions concentrations, it helps to internalize and conceptualize the principles used to create those formulas. When diluting a solutio...

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