Physical Attraction... Chemical Reaction

"Before we were doctors, we were med students, which meant we spend a lot of time of studying chemistry. Organic chemistry, biochemistry, we learned it all. But when you're talking about human chemistry only one thing matters: either you've got it or you don't. Chemistry, either you've got it or you don't."

- Meredith Grey

Physical Attraction... Chemical Reaction is the seventh episode of the fourth season and the 68th overall episode of Grey's Anatomy.

Short Summary
Hahn bans Cristina from her service, Bailey covers more and more of Torres' duties, and Izzie and George go to extreme lengths to recapture the magic of their first encounter.

Full Summary
It's all about chemistry. You either have it or you don't. In trailer land, Derek is starting to wonder what he got into... with the Chief. Richard is dropping off his dry cleaning with Derek and also making plans to watch The Godfather with him later. Mark jokes that Derek and Richard and dating.

Richard tells Callie that, as chief resident, she needs to clean up her act. Callie asks Bailey to cover her and be chief resident for the day because she has back-to-back surgeries and, well, Bailey's better.

Dr. Erica Hahn wants Meredith for her service to see if she inherited Ellis' chops. But she's interrupted by George, who confides in Mer that sex with Izzie is horrible. She's trying to channel a porn star and it just isn't working. Moments later, Izzie finds Meredith alone and complains that George kisses like a chicken!

Alex's patient, Jerry, hasn't had a bowel movement in five days, while Dr. Yang, having been ousted from cardio by Dr. Hahn, treats a woman, Teresa, who fell down the stairs while carrying her baby, and suffered some mild head trauma. The baby is still breathing, but Teresa faints and can't. Her husband, Sean, confides that they only recently adopted the baby and she doesn't even have a name yet.

Dr. Hahn and Meredith operate on Teresa as Cristina and Mark watch from the gallery. Both of them are jealous at this moment - but are in love with Dr. Hahn. Cristina wants to be her understudy, while Mark repeats over and over that he has a thing for the new head of heart surgery.

At home, Izzie and George try again, but it goes worse than ever. There is more pecking, overly rough behavior and even some fantasies better left unfulfilled. George thinks he chipped a tooth!

Alex's and Izzie's patients are causing them consternation, and Lexie (who has taken over the baby) joins them in looking for Callie to help, but it is Bailey who tells them what to do and then covers for Callie in front of Richard. Lexie's problem isn't exactly solved, because Sean tells her that he can't raise a child on his own and that doesn't want to keep her.

The boy who swallowed marbles to make his parents take him seriously now comes back to the hospital after having swallowed more ... except this time, they are magnets, which are ripping through his stomach and organs and must be operated on ASAP.

After their shifts, Meredith and Derek have sex in Derek's trailer, but he forgets that he was supposed to have dinner and a movie with Richard. So the Chief walks in on them of course. Meredith goes home to find Alex hanging out outside of the house because Izzie and George are inside, trying to have better sex with the help of a "box of fun" and booze (which doesn't work, it's worth noting).

Lexie comes over to ask Alex to have a drink at Joe's. Meredith rips into her and tells her she's not allowed to have drinks with Alex or sleep with Alex, and to get her own life and her own friends. Lexie tells Meredith to screw herself, while Alex asks Mer why she cares so much if she doesn't even consider Lexie to be her sister, as she has said in the past.

Alex and Izzie find their patients - who Bailey had them put in the same room to annoy each other and make them focus on getting better and going home - having sex with the curtains drawn. Izzie says it is unfair that even this odd couple have chemistry when she doesn't with George.

Mark tells Derek that he has a thing for Dr. Hahn. Richard joins them to have a "lovers' quarrel" with Derek. The conversation makes Richard see that Bailey has been doing all of Callie's chores and making Callie's decisions for. Richard catches up with Callie and demotes her.

Lexie sits with Sean when Meredith comes out of Teresa's surgery. Meredith tells the man that some people just need more time to bond with the baby and to feel like a family. Lexie is sitting there and takes these words to heart regarding her own life as well. Hahn and Meredith patch up Theresa's lungs, but there are too many leaks and she doesn't make it.

Lexie finds Alex and asks him to meet her in the on-call room. He says he can't because he doesn't want to get involved with Lexie's problems with Meredith. But when Sean - who had left the hospital after his wife died, abandoning the baby - returns and names it Keisha, Lexie feels a renewed sense of hope that she should go after Mer and make it work.

Richard tracks down Bailey, outs her for doing all of Callie's work, then credits her for all she has done and admits he should have made her Chief Resident from the very beginning. She says that it's about time that he noticed, and then bursts into tears. She throws her arms around him.

After rounds, Lexie finds Meredith and tells her five things about herself, in hopes of making her older half-sister know her better. Later, Lexie is at Joe's and feeling miserable. Meredith asks Alex if he would please take poor Lexie home. Alex drives Lexie home to find Thatcher drunk off his ass. Alex gets in his face when he wants to drive to the store, which irritates Thatcher. Lexie asks Alex to keep this a secret.

Callie homes to find Cristina painting after a day of not getting what she wants. Callie confides in her that she got fired. At Joe's Mark tries to put the moves on Dr. Hahn while playing darts but is completely, utterly shot down. Richard tells Derek that he married Adele two years out of college, and doesn't know how to do things. Meredith at last wants to stay a little while after sex with Derek.

Izzie and George go at it yet again... and confess how great it was. They do have chemistry after all! Then they call each other out for lying.

Main Cast

 * Ellen Pompeo as Dr. Meredith Grey
 * Sandra Oh as Dr. Cristina Yang
 * Katherine Heigl as Dr. Izzie Stevens
 * Justin Chambers as Dr. Alex Karev
 * T.R. Knight as Dr. George O'Malley
 * Chandra Wilson as Dr. Miranda Bailey
 * James Pickens Jr. as Dr. Richard Webber
 * Sara Ramírez as Dr. Callie Torres
 * Eric Dane as Dr. Mark Sloan
 * Chyler Leigh as Dr. Lexie Grey
 * Brooke Smith as Dr. Erica Hahn
 * Patrick Dempsey as Dr. Derek Shepherd

Guest Starring

 * Jeff Perry as Thatcher Grey
 * Rockmond Dunbar as Sean Brotherton
 * Stephanie March as Jane
 * Vicki Lewis as Harriet
 * David Burke as Don
 * Kurt Fuller as Jerry
 * Enuka Okuma as Teresa Brotherton

Co-Starring

 * Braeden Lemasters as Brian
 * Mark Saul as Intern Steve
 * Amrapali Ambegaokar as Intern Dani
 * Linda Eve Miller as E.R. Nurse

Notes and Trivia

 * This episode's title originated from the songs Physical Attraction and Chemical Reaction, originally sung by Madonna and Snyderman respectively.
 * This episode scored 19.50 million viewers.

Quotes

 * Bailey: I am so right about so many things, it will make your head spin.


 * Mark: You want finesse? You should try plastics, it's all finesse.
 * Cristina: Yeah, no room for error when you're dealing with someone's face
 * Mark: It's more than just face lifts. I'm a board certified ENT, I take out tumors. (after a pause) It's also a lot of face lifts.


 * George: Hey.
 * Meredith: You look weird.
 * George: I don't look weird.
 * Meredith: What's wrong?
 * George: I look fine.
 * Meredith: I know you.
 * George: It's horrible. The sex. With Izzie...(whispers) horrible. It's like she's trying to hard i-its...you ever seen a porno? Not that Izzie's a porno; she's an angel, but it's like she's trying to...channel a porn star and she's trying to act all dirty and sexy, which sounds great, right? But in reality I just wanna say, "Izzie, just because you can do that with your legs doesn't mean that you should."
 * Meredith: (winces and sticks her finger in her ear) Eh... I wanna run.
 * George: Run, run. Run now!


 * Izzie: I love George.
 * Meredith: Oh, God...
 * Izzie: I do, I love him, and I'm so happy because he's kind and smart and um, sweet and sexy. He's perfect, perfect, except for the fact that he kisses like a chicken. You know a chicken pecking the ground for food, justs pecking and pecking and pecking, and when he's pecking at me like that I forget that I love him, I forget that he's kind and sweet and sexy and I just wanna scream, "Stop pecking me!" Did he peck you like a chicken, Mer?
 * Meredith: (sees Cristina) Cristina needs me.