CHEMISTRY COMMUNITY

Angelo Mapalo 4E

These prefixes typically apply to polydentate ligands.

Angelo Mapalo 4E

If the overall charge of the compound is negative, then you add an -ate, otherwise you just state the metal. There are actually exceptions to this -ate rule. Copper -> cuprate and iron -> ferrate.

Angelo Mapalo 4E

You count the sig figs after the decimal point when calculating with logs.

Angelo Mapalo 4E

We didn't cover those topics. At least not in very much detail, so I don't think you would have to know them.

Angelo Mapalo 4E

Why can the cis- version of the complex form 2 bonds and why can the trans- version of the complex only form 1 bond?

Angelo Mapalo 4E

How can we tell if the chelate is square planar or tetrahedral? Will we have to choose between the two on the final?

Angelo Mapalo 4E

Strong bases are completely ionized in water and consist of alkali metal and alkali earth metal oxides (groups 1 and 2). Weak bases are not completely ionized in water like ammonia.

Angelo Mapalo 4E

Strong acids produce more protons in a solution than weak acids. Strong acids also assumed to be 100% ionized/dissociated in a solution while weak acids are not.

Angelo Mapalo 4E

What are some example of compounds that are Lewis acids/bases but not Bronsted acids/bases? And vice versa?

Angelo Mapalo 4E

The 3d10 and 4s1 implies that the 4s shell gave one electron to the 3d shell in order to make it more stable. 3d9 and 4s2 -> 3d10 and 4s1 is an exception made by copper. Also the 4s shell is written before the 3d because it has higher energy. Reading it off the periodic table can be confusing becaus...

Angelo Mapalo 4E

Cisplatin and porphyrin(->heme complex->myoglobin->hemoglobin) seem like important biological examples that have come up.

Angelo Mapalo 4E

Cisplatin is well known for being used in chemotherapy. It forms a coordination compound with DNA to stop cell division.

Angelo Mapalo 4E

I've seen the questions worded as "Identify the composition of each bond and the hybridization of each lone pair" for questions that use that notation. I'm not sure if this is the situation you are talking about, but for example the hybridization of lone pairs of oxygen can look like O(sp ...

Angelo Mapalo 4E

I went to a review session and essentially the TA explained that there isn't enough room on a single N to have multiple sites. He said think of each individual atom as a site instead of lone pair.

Angelo Mapalo 4E

This was a question on the midterm. "How many electrons in bromine possess identical values for the first two quantum numbers, n and l, as the unpaired electrons? Include the unpaired electron in you answer." How do we find the amount of electrons with identical values?

Angelo Mapalo 4E

“Which pair of atoms in thymine are most tightly bound and why? C=C, C=O, C=N”

Sorry if sigma and pi bonds don’t relate to this question.

Angelo Mapalo 4E

Why is C6H6 neither an acid nor a base?

Angelo Mapalo 4E

We may not have to do any calculations using the equation, but my TA said we should understand Schrodiner's equation conceptually.

Angelo Mapalo 4E

Does higher pOH indicate a more basic or acidic solution?

Angelo Mapalo 4E

For question 2E.25(a), could you draw the lewis structure for CH2Cl2 so that the dipole moments cancel out? What makes this molecule polar?

Angelo Mapalo 4E

A is the central atom and is typically 1. X is the number of atoms bonded to the central atom. E is the number of lone pairs around the central atom, A. The VSEPR formulas is very useful in determining the shape of the molecule.

Angelo Mapalo 4E

Electron affinity increase going to the right and upwards along the periodic table. It is the same trend as electronegativity. You can always look in the direction of Flourine since it's the element with the highest electronegativity.

Angelo Mapalo 4E

Dipoles cancel when dipole moments of equal strength go in opposite directions.

Angelo Mapalo 4E

In general, the longer the bond length, the weaker it is. Also, multiple bonds results in short bonds meaning they are generally stronger.

Angelo Mapalo 4E

Double and triple bonds aren't considered because the VSEPR model focuses on the regions of electron concentration. Each bond, whether single or multiple, acts as a single unit when counting regions of high electron concentration.

Angelo Mapalo 4E

When finding the magnetic quantum number m_s, is it always+ 1/2? Or can the spin orientation be found?

Angelo Mapalo 4E

Since the arrangements of the electrons remain the same, I don't believe you'll have to draw separate resonance structures.

Angelo Mapalo 4E

The step up sessions for Monday (no step-up sessions Tuesday) are in Young Hall Room 1032-3 from 11AM-12PM and Room 1023-1 from 1-2PM. You can find out more from this link: https://lavelle.chem.ucla.edu/wp-content/supporting-files/Chem14A/Chem14UA_PL_ALL.pdf

Angelo Mapalo 4E

Step-up sessions could help reinforce your knowledge of a topic even if you have a firm grasp on it. I'd recommend going if you want practice and review.

Angelo Mapalo 4E

How many more valence electrons can phosphorus, sulfur, and chlorine accommodate with their expanded valence shells? Why?

Angelo Mapalo 4E

Single and double bonds are drawn in Lewis dot structures, but those bonds are capable of being different equivalent locations. Electrons move around so that actual bond length is equal, representing the average bond length of the structure. This is represented in resonance.

Angelo Mapalo 4E

Yes, you find the formal charge of each bound atom.

Angelo Mapalo 4E

How should resonance structures be drawn? The arrows indicated between the various structures or the organic chemistry shapes?

Angelo Mapalo 4E

How do we determine which structure is the most stable with formal charge?

Angelo Mapalo 4E

Resonance is the blending of electron structures. They have the same arrangement of atoms but different arrangements of electrons.

Angelo Mapalo 4E

Positive means it's spinning up, negative means it's spinning down.

Angelo Mapalo 4E

Increasing the intensity of light does not result in an ejected electron because in this experiment, the light is acting as particles (photons). Increasing the light would only increase the amount of photons, not how much energy each photon has. So if one photon doesn't have enough energy to eject a...

Angelo Mapalo 4E

My TA recommended learning polyatomic ions, which will help you determine certain formulas from word problems. Here's a link to a few common ones: http://www.iun.edu/~cpanhd/C101webnotes ... salts.html

Angelo Mapalo 4E

The principal quantum number (n) tells you which energy level (shell) the electron is in. The angular momentum quantum number (l) describes the shape/orbital (s,p,d,f). The magnetic quantum number (m) labels different orbitals of a subshell/orientation.

Angelo Mapalo 4E

How is the m value determined within a set of quantum number?

Angelo Mapalo 4E

A few clarifying questions about when an electron transitions quantum levels. When they transition to a lower level, do electrons decrease the energy of an electron? Does that decrease in energy for the electrons increase the frequency of light emitted?

Angelo Mapalo 4E

You would have to compare those calculated moles to the required moles. An easy way to look at it is using ratios. You could find the value of one mole and apply that to ratio of moles of the chemical equation. Using the ratio, you can determine how many moles are needed for the other reactants by d...

Angelo Mapalo 4E

How do constructive and destructive interference interact to create diffraction patterns of light? What is the relationship?

Angelo Mapalo 4E

You would use De Broglie's equation for any moving particle with momentum and has wavelike properties with wavelength. You would typically use it for small objects with a small enough mass. Typically, a wavelength with less than 10^15 meters dies not have wavelength properties.

Angelo Mapalo 4E

The "unexpected" aspect of the photoelectric effect is the fact that, unless there are greater than or equal photons to energy remove electrons, electrons are not emitted for even high intensity light.

Angelo Mapalo 4E

I believe it will be different for every TA, but my TA said the correct use of sig figs will be part of his grading.

Angelo Mapalo 4E

Can someone elaborate a quick statement from the textbook? "In practice, gaseous mixtures are not thought of as solutions, even though one gas might be dominant (such as nitrogen in the atmosphere)." Is it improper to call gaseous mixtures solutions? Or are gaseous mixtures incapable of be...

Angelo Mapalo 4E

The first zero, the leading zero, is not significant.

Angelo Mapalo 4E

I think the left side is what is typically used for APA (and MLA) format.

Angelo Mapalo 4E

I was wondering how many sig figs do we apply to percentages when we're only given a molecular/empirical formula.

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