8 major changes 'Lessons in Chemistry' has made from the bestselling book (so far)

In the book, Elizabeth brazenly enters Calvin's lab at Hastings Research Institute one day in search of some equipment for her own undersupplied lab.

During their terse exchange, Calvin insults Elizabeth by assuming that she is a secretary, leading to her marching out with a box of beakers. Several days later, Calvin finds her and apologizes but Elizabeth shows no interest in making amends.

This is slightly altered for the show which shows Elizabeth working on her abiogenesis research after work hours. She sneaks into Calvin's locked lab and swipes a bottle of ribose from his shelves.

The next day she finds herself confronted by Calvin, who mistakenly assumes she's a secretary and accuses her of stealing the bottle to sell on the black market. He even calls her a "fibber" when Elizabeth tells her she's a chemist, just like him. It's only when Calvin puts in a formal complaint about Elizabeth to Miss Frask (Stephanie Koenig), that he realizes she isn't lying.

In the book, there is no mention of the Little Miss Hastings pageant, which Elizabeth is begrudgingly forced to participate in as "Miss Aminos" after she receives a formal warning about her behavior.

It's while grabbing her coat and making an early exit that Elizabeth encounters Calvin again, who at that very moment vomits on her.

In the book, this second meeting between Calvin and Elizabeth takes place at a theater following an opera performance the two both happen to be at, and it's Calvin's reaction to a date's perfume, rather than Mrs Donatti's that makes him nauseous.

Rather than be a serendipitous encounter as it is in the book, in the show Calvin reveals that he had actually attended the pageant to see Elizabeth and gift her the bottle of ribose as an apology for his rude remarks.

The first episode introduces viewers to Harriet Sloane (Aja Naomi King), who doesn't appear until much later on in the book. Calvin's neighbor doesn't come into the story until after Elizabeth has moved in with Calvin. In fact, readers do not see Calvin interact with her at all.

But in the show, Harriet is shown to be a part of Calvin's daily life — in fact, it's shown that he even babysits her children sometimes.

Her role in the series has been expanded to introduce a new storyline about the neighborhood where she and Calvin live being under threat of being demolished to make way for a new freeway.

The second episode of "Lessons in Chemistry" opens with a flashback to Elizabeth's days studying at the University of California, Los Angeles (UCLA), and audiences learn the reason why she never managed to get her PhD.

Shortly after submitting her proposal, she finds herself on the receiving end of unwanted sexual advances from her professor and personal mentor, Dr. Bates, a character who has been invented for the show. When she tells him she doesn't see him that way, he forces himself on her.

However, in the book, it is the older, lecherous Dr. Meyers who rapes Elizabeth in a brutal attack after finding her running last-minute tests on his latest research project late at night in the university lab.

In both the book and the adaptation, Elizabeth is able to stop her assailant by stabbing them in the gut with a pencil but pays the consequence of losing her place on her course when she refuses to offer a statement of regret.

Shortly after she is transferred to Calvin's lab so she can focus on her abiogenesis research, Elizabeth requests to be moved back after an exchange with Calvin brings up memories of her attack.

When she isn't allowed to, she decides to set up boundaries in their shared lab and begins acting coldly towards him.

None of this occurs in the book, but it helps underscore Elizabeth's apprehensive about growing close to Calvin, in case he turns out to be like other men she has encountered, or it jeopardizes her position at Hastings.

In the second episode, Elizabeth finds a stray dog sniffing around the trash cans in her backyard, and taking pity on him, makes him a plate of fresh food. Later on, it's made clear that she's adopted him when she brings him to Calvin's house.

When asked what his name is, Elizabeth says it's Six-Thirty "after the time he wakes me up in the morning. It's like clockwork."

In the book, Six-Thirty shows up in the story after Elizabeth and Calvin have begun living together and decide to get a dog together.

He follows Elizabeth home from a nearby deli and gets his humorous name after Calvin asks Elizabeth who her friend is and, mishearing him, Elizabeth looks at her watch and reads him out the time.

In the book, Six-Thirty is described as "tall, gray, thin, and covered in barbed-wire-like fur," which brings to mind a dog like a Lurcher.

However, in the adaptation the failed bomb detection dog is shown to be a Goldendoodle — a cross a Golden Retriever and a Poodle that didn't come about until the 1990s.

At the end of the second episode, Elizabeth lays out the reasons why she never wants to get married or become a mother: for her, it would mean giving up everything else.

Calvin thanks her for letting him know and reassures her that "as long as I have you and you're happy that is enough for me."

These events unfold very differently in the book; even though Elizabeth has made her feelings about marriage clear, Calvin still tries to propose to her with a ring over lunch one day at Hastings.

He also has a hard time understanding why she's so opposed to not only marrying him but changing her last name to his and reveals that he has already added the name "Elizabeth Evans" to the deed of their home.