#vsepr

[leatheslay]

girl you're looking so. tetrahedral today :3

[homeostasister]

Learning about chemical bonding in intro chemistry class is so funny because it’s like “so this is how atoms form bonds. Yep, that’s pretty much what happens. Actually, that model is a little oversimplified, this is how atoms form bonds. Actually, that’s still an oversimplification, this is how atoms really form bonds. Okay, that’s also an oversimplified model, this is the actual way that atoms form bonds.” I’m learning molecular orbital theory right now; I think that’s the last bonding model this class is going to cover. I don’t know if there are others lurking in the murky depths somewhere.

[can-we-die-now]

*boytoy listing topics in chemistry he doesn't know*

i don't know MOT

i don't know VIBGYOR...

wait no...

eagle: do you mean VSEPR?

[sciencesolutions]

[whats-in-a-sentence]

VSEPR predicts that a tetrahedral geometry is favoured for a coordination number of 4, but both tetrahedral and square planar geometries are found for 4-coordinate complexes, and these are illustrated in figures 13.14 and 13.15.

"Chemistry" 2e - Blackman, A., Bottle, S., Schmid, S., Mocerino, M., Wille, U.

[studentbyday]

Why we need VSEPR

VSEPR stands for valence shell electron pair repulsion theory. The initial idea was that electron pair(s) in the valence shell repel each other, affecting the molecule's shape. But we now know this doesn't apply just to electron pairs. You could also be talking about a single electron if you have an odd number of electrons, double bonds where the bond = 2 pairs of electrons, or triple bonds where the bond = 3 pairs of electrons. This region of space occupied by the electrons causing repulsion = the domain, which is not necessarily the same thing as orbitals. Either way, we live in a 3D world, so VSEPR theory giving us 3D molecular shapes gives us more info than Lewis structures can.

What VSEPR tells us that Lewis structures cannot:

If two structures superimposable, they're the same molecule. Lewis structures don't show this (you may have different Lewis diagrams for the same molecule). Say you have this compound CH2ClF and you move the Cl and F in the Lewis structure. It's still the same molecule when you look at it in 3D because you can rotate the molecule in a certain way and see that the molecules represented by the two Lewis structures superimpose.

If two structures are NOT superimposable, they're not the same molecule. Lewis structures don't show this either (you may have 1 Lewis diagram for different molecules). Say you have the compound CHBrClF. From the Lewis structure, you can't tell that there are different ways you can structure this molecule in 3D space. If you were to look at it in 3D, you'll see there's no way to rotate the molecules and have the two structures be the same. (This is why VSEPR is really useful for organic chemistry because you have lots of isomers - stuff with the same chemical formula but different structure like this. This kind of isomer in particular is called an enantiomer.)

[strawberryona]

i'm on lacemade and dracula clothing looking for things to put vesper in :D

[andromeda3116]

boy i love getting tipsy and then drunk and gushing about my special interest to people who cannot possibly care about this even half as much as i do and being deeply annoying and embarrassing myself and wanting to crawl into a hole once the harsh light of sobriety hits

[portrait0fthem00n]

I was made to babygirlify fictional men and read my sapphic books all day, instead I have to study vsepr and molecular symmetry operations :((

[sleepintro]

DOES ANYBODY HERE KNOW FUCKING CHEMISTRY

[tenth-sentence]

All of these compounds contain 4 sets of electron pairs and therefore, according to VSEPR theory (p. 176), their structures are based on the tetrahedron, with 0, 1, 2 or 3 lone pairs.

"Chemistry" 2e - Blackman, A., Bottle, S., Schmid, S., Mocerino, M., Wille, U.

[fru1tb3tz]

guys will see this and just think "hell yeah"

[kaise-mein-kahun-tujhse]

Even I don't want to 😭😭

It's not even like I CAN'T do it. I basically don't WANT TO

[kyoghurts]

I WILL.

hq. kuroo tetsurou/reader

listen, its like this: i know you would do the same for me. but that no one ever told you to in the first place, you just do it. you can and you will, because you want to, you would do it for him, and he would do it for you.

( or: he’s yours and you’re his, isn't it obvious enough? )

tags. fluff hehe. 1.9k wc. taking care of each other like it’s breathing. i actually…based off some of this from my personal experience, we’re not a couple though we just have each other’s back as friends :]]]

“why him?”

there's a curious gaze that's locked into place when kenma had asked you, something you usually don't see everyday.

you stand there, stammering. "uhm, about tetsu?"

kenma blinks, noncommittal.

kuroo tetsurou's rolling in the aisles about what bokuto had been proving for almost an hour (you don't exactly hear their conversation, though you can guess it regards to their recent hyperfixation of a series you only ever knew because your boyfriend couldn't stop babbling for days). bokuto's voice reverberates through the room, big and joyous, and tetsurou's turning red and his laugh is reduced to desperate wheezing.

"he takes care of me." you say after a moment. "the same way i take care of him."

the little grin you have is demure, but so full of tenderness. you tell kenma of the time you’re fifteen and kuroo barely knows of your existence even when you’re both classmates because of the fact that, well, you never really looked at him, and he never looked at you too. always on the corner of his space, there but not touching, not quite, not enough. there’s not enough reasons to meet, not enough to set foot into his view.

that is what you believed, until midterms rolled by.

───・・✦

“that’s a trigonal bipyramidal”

“huh…?”

a day of revising. you realize he’s sitting a little more close to you than before, leaning towards to skim through your paper. there’s an unreadable look on kuroo’s face that makes you blink, now you’re feeling awkward, he gently takes your pencil from your grasp and wrote down something.

“it…has no lone pairs” you know this, although it comes to you a little more slowly. digesting chemistry into your system isn’t your thing, but it seems the opposite for kuroo.

his lips curve, eyes bright. “yeah, and the VSEPR notation is—“

“AX-sub five.” you both say.

“yeah!” kuroo softly exclaims, nervousness spreads across your chest, shows in the way you play with your fingers. you’re sure he notices, because the next thing he says is “oh, sorry, just saw you a bit lost back there”

“i was.” you’re the first to break eye contact. his gaze is almost too much, or maybe you’re just not used to it. “…thank you.”

“you’re welcome” your name on his lips, like a gentle push to your heart, the first time you’re fully aware of what it means to meet. its scary. it’s exciting. “let me know if you need any help.”

you take the chance, now you’ve got a plus one reason to enter his space, which is plenty. “…will you teach me?”

(he taught you better that day than anyone ever could.)

listen, its like this: i know you would do the same for me. but that no one ever told you to in the first place, you just do it. you can and you will, because you want to, you would do it for him, and he would do it for you.

like the class debate that started to heat the atmosphere because kuroo does not back down but you’ve gotten really good at discerning the art of him, his snide remarks increasing rapidly, his mind running short, spatting illogical fallacies, still, it takes him a second when you rub his back in slow circles with a pat. silent but supportive. a short pause, then he breathes.

he’s back out there and you trust him to bring back triumph to you. he trusts you to be there for him, too.

(it could mean nothing, but it could also mean something—you’re inclined towards the latter. the way he held the small of your back, as if to share this little victory with you, during the walk home.)

(perhaps its his way to know he’s there, to slowly be in your space, these small touches, small moments. perhaps you like it, you like to see more of him, to be close in each other’s spaces.)

“ugh” you end up grimacing when you try to swallow, your throat hurts so bad. “fuck, i need water.” you mutter against your breathe, already pushed beyond your limit.

“i think they’re still open” kuroo points upstairs, his tone unsure. “the teachers’”

you raise a brow, but he’s already taking long strides and you realize this a second late that you had to rush to him and curse his long legs and then stumble through your words. “i don’t have my wallet” it hurts to talk, you don’t know if its the soreness of your throat or the lingering embarrassment of the fact that you don’t take care of yourself as much. perhaps its both, the latter is the cause and the result is—this.

kuroo, now considered to be one of your closest friend, gentle written in his eyes and laced within his voice, reassures you to “relax, this is the least i can do. you’ve already been through enough”

its the finals, almost at the finish line when your body takes a toll on you—sore throat, headaches, persistent fever, it all crashes down as if you gave into your own weight, dead and heavy. you were already tired last week, but you’re too stubborn to listen to your own body, your own needs. and you’re not surprised anymore when you wake up shivering and aching, you know you deserved this.

you frown. you don’t even want to know your exam scores, once this is over, you’ll start teaching yourself to listen to the call of your needs. you’ll teach yourself to be kind, to give in, because that is a form of strength in itself. a skill to be used for a lifetime.

he told you this. the moment you sent the text ‘guess who got themselves sick :P definitely NOT me’ he’s already dashing to your place with essentials and you didn’t even mention any details yet, his face both a scowl and of worry. your mouth opens to utter something and he thinks your spilling nonesense because he won’t leave until he knocks some plain sense into you. his words. that was what he said. it stuck with you ever since.

he stuck with you ever since. like some glue you don’t to wash away from your skin, close and comfortable.

the silence that which accompanies the two of you are what you thrive in, you wonder if he feels it too. as you’re both walking down the hallway, everything feels soothing: the sway of his arms on his sides, his faint hums, the unintentional bumps, and the treacle-like slow of grin appearing on your face. he didn’t have to do any of this, he didn’t have to worry about you, or your well being.

(but its not like it bothers you.)

(or him, for that matter.)

after he paid your water and handed it to you, he looked as though he’s thinking hard. of what, you don’t know, you’re about to ask him of something you never felt so sure of.

at least, at this point in your life, you’ll allow yourself to give in.

“kuroo—“

“no.”

your heart drops for a second. “…what?”

“i mean” he rubs his nape, looking anywhere but you. “you call your close friends by their first name, i…want you to do the same to me”

“oh.” the water you just drank felt useless, you set them aside, your chest tightens and your throat constricts itself in a way it’s not supposed to. of course you’re scared, this is your first, after all. your first to like someone beyond infatuation, beyond of “just because”, and oh, it’s leaving you so speechless.

“tetsurou” you try it in your tongue. it tastes rather sweet.

“mm” he couldn’t agree more, if the pink in his cheeks traveling to the tips of his ears says anything. “now it feels real.”

“feels real?” he steps forward, brushing your hair absentmindedly.

“that we’re close.”

you place your hand over his, which eventually rests at the side of your face. you look at him. he looks at you. “you want this? you want to be closer?”

he nods, his eyes turning misty. “more than…god…..yes. more than you’ll ever know.”

you do the same—although twice. you nod twice to affirm him, you cup his face with both your palms to not let him or you fall astray. you say, “i want this too. more than i can express.”

you smile, presenting yourself whole. he presses your forehead with his and exhales, “you can start by showing up at our match this week. you’ll cheer for me, won’t ya?”

you had already set the date on your calendar, chuckling. “of course, tetsurou.”

the highest level of happiness sits with tetsurou, as if he had won the match himself. but that he had won your heart instead. “thank you, thank you.”

(you’ve been there for him, and you’ll be there for him again, because you can, because you choose to be.)

───・・✦

kenma could lie at this moment to be polite, that he understood entirely. he could be nodding and averting his gaze or he could even utter nothing at all.

though there’s a multitude of things he could do, he tilts his head instead. pensive. you hear him hum slowly, “so, you’re the one he opened up to me about how there’s this person he couldn’t approach back then. he sulked for days.”

you couldn’t help but laugh. it’s almost silly when you try to imagine it.

“and then midterms. that explains why he was…” he grimaces, “acting like a girl in love.”

it cracks you up. he’s probably traumatized by the sight. “i feel like you’re just backstabbing him now.”

“i am.” the edges of his lips curl, soft things, such a rare view to behold.

“what else did he show?”

“you’re backstabbing him too.”

“i need to know!”

“know what, sweetheart?“

kenma, just as quickly as it goes, looks at tetsurou dead in the eye. “none that concerns you.”

you look up at man you’ve been talking about since the start and turn quiet, teasing him further.

he looks at you, at your feigning clueless expression, and as if flustered he stutters “it’s about me, am i right or am i right???”

“everything isn’t always about you, kuro.”

“you’re acting defensive kenma! and you!” he points at you, holding it in with your hand clasped against your mouth. your face warm. shoulders shaking as you contain yourself. he walks up to you with arms finding purchase at the dip of your waist, he lowers his voice, coaxing you “what’s gotten you so happy now, hm?” it’s contagious, he thinks.

you echo kenma, as you offer nothing but a peck to his cheeks. “like what he said, it’s nothing.”

“i knew leaving you with him was a bad idea.” you wave when bokuto hollered something about he’ll be back in a minute. kenma swiftly excuses himself but also makes an imitation of texting and your brows crease in a sense of knowing. “see what i mean? what was that??”

when you turn to him, warmth flourishes. “you know how i feel about you, right?”

“that’s sudden.” he takes in your sight, combing your hair, a habit of his you’ve come to adore. “i do know, why do you ask?”

“are you sureee?”

“yes. i’m sure.” and then, with both hands now cupping your face, he kisses you. short and sweet. “never been so sure in my life.”

the highest level of happiness sits with you in a manner so similar to his. “thank you, tetsu. thank you”

© kyoghurts. ★ reblogs & likes are well appreciated!

[whats-in-a-sentence]

To determine the shape of a molecule using VSEPR theory, we use the following procedure:

Determine and draw the Lewis structure of the molecule.

Count the number of sets of bonding pairs and lone pairs of electrons around any inner atom, and use table 5.2 to determine the optimum geometry of the sets. Note that VSEPR theory makes no distinction between electron pairs in single, double and triple bonds. Each is treated as being one set.

Modify the geometry, if necessary, to take account of the fact that the magnitudes of repulsions between sets of electron pairs depend on whether the electron pairs involved are bonding pairs (BP) or lone pairs (LP). The repulsions are in the order: LP-LP > BP-LP > BP-BP

This is satisfied by placing the two sets in a linear arrangement (table 5.2) and results in a linear shape for this molecule, with a H-Be-H bond angle of 180°. (...) The optimal geometry for three sets of electron pairs is trigonal planar (table 5.2). (...) The optimal geometry for four sets of electron pairs is tetrahedral (table 5.2). (...) The geometry which places these as far apart as possible is trigonal bipyramidal (table 5.2). (...) An octahedral geometry of the six sets (table 5.2) places them as far apart as possible, as shown in figure 5.17b.

"Chemistry" 2e - Blackman, A., Bottle, S., Schmid, S., Mocerino, M., Wille, U.

[studentbyday]

Molecular and ionic compound structure and properties Pt. 2

Part 1 here

Lewis diagrams/structures

Lewis diagrams show how valence electrons = distributed around atoms in a molecule; thus, in general, follow the octet rule

Shared pairs of electrons are drawn as lines b/t atoms

Lone pairs of electrons are drawn as dots next to atoms

Goals for every Lewis diagram:

Have the correct number of total valence electrons (v.e.)

Each atom has the correct number of valence electrons for that atom

Ensure the way electrons are shared fulfills the octet rule for every atom unless it's an exception: For H, instead of octet rule, it's just 2 valence electrons (duet rule). Boron and Al can form stable molecules where they only have 6 v.e., not 8. 3rd period and beyond: atoms can form stable molecules where they have more than 8 v.e. (this may happen because these atoms can put electrons in their empty valence d orbitals? but this is a subject of debate)

To make a Lewis diagram:

Count total number of valence electrons in compound. If compound has a negative charge, add an electron to the total for every negative charge. If compound has a positive charge, subtract an electron from the total for every positive charge.

In general, put the least electronegative atom that is NOT hydrogen in the center of the diagram - more electronegative atoms or H are terminal atoms (atoms on the outside).

First, assume single bonds. Subtract the electrons used from the total.

Assign leftover electrons to the terminal atoms. Subtract the electrons used from the current total number of unused electrons.

If needed, assign any leftover electrons to the central atom. If the central atom has an octet or exceeds an octet, you're usually done. If the central atom does NOT have an octet, create multiple bonds until you do.

Resonance and formal charge

Resonance occurs when a molecule or ion has more than 1 valid Lewis structure, e.g. nitrate - with the 1st 3 possible Lewis structures, you'd think 1 of the bonds (the double bond) is shorter and has a higher bond energy than the others, but in reality, all 3 bonds have the same length and energy.

Each molecule or ion that experiences resonance truly exists as a resonance hybrid - the weighted average of the possible Lewis structures ("resonance structures"), a hybrid of the possible Lewis structures (not alternating b/t the different structures). E.g. in nitrate, each bond is someplace in b/t a single and double bond b/c the molecule's electrons are delocalized throughout. It's a weighted average because for some molecules/ions, some resonance structures contribute more to the resonance hybrid than others, aka the molecule/ion has nonequivalent resonance structures.

Formal charge = the charge of an atom in a molecule if all the bonding electrons were shared equally. It helps us determine w/c resonance structures contribute most to a resonance hybrid.

The closer a resonance structure's formal charges is to 0, the more likely it is to contribute more to the resonance hybrid compared to other resonance structures.