Why do you think that Riddle picked Ginny? I mean why not Hemione? Is it suposed to start off the love between them?!?

^ Yeah, but I'm sure voldemort pretty much told him to pick Ginny. Hermione wouldn't stupid enough to trust the diary, and ginny's really the only other girl who's even remotely close to Harry. I mean she's his best friend's little sister.

True, Lucius disliked the Weasley family. Tom did not necessarily choose Ginny, just used the situation to his advantage.

Another reason, perhaps Riddle told him to pick the youngest (or female) of the Weasley family; because he would view her as the weakest or most vulnerable. This is due to Riddle's arrogant nature & he was able to manipulate her to trust him (especially when he learned of her crush on Harry).

But Lucius Malfoy didn't know that he was holding a bit of his master's soul in his hands! He wouldn't have thrown it away to some girl if he'd known it was a horocux.
But there was Lucius, having an old book Voldemort hade left him, and he just thought it was a magic object, full of dark magic.
So, he thought that if Arthur Weasley's child was found with a thing like that, he would be fired from the Ministry. And Lucius wanted to punish the Weasleys, because they were truck with muggles. And he hated them.
Poor Lucius, Voldemort couldn't have been happy when he found out that one of his horocuxes hade been destroyed

Lucius was under investigation by the ministry. He was trying to get rid of some old magical things so they would not be found at his house. He took the first oppurtunity to ditch the book.

Riddle didnt. Lucius Malfoy did. He didnt know that th diary was a Horcrux and he wanted to get rid of the book, and took a chance by putting it in Ginnys cauldren.

Lucius picked Ginny to discredit Arthur who was trying to get a "Muggle Protection Bill" passed by the Wizemagot. He thought when it came out that Arthur's daughter had opened the Chamber and been behind the attacks on Muggleborns, it would make Arthur a hypocrite and his Bill would be voted down.
Voldemort had nothing to do with it. As the poster above pointed out, Lucius thought Voldemort dead, he only knew that the influence of the Diary would open the Chamber. He had no idea it was a Horcrux.

Cause Ginny was really vulnerable, and partly because of what Olli said

I agree ... as even Voldermort says in a nutshell that he is disapointed that even Lucius believed him to be dead and didn't bother looking for him.. so it would seem Malfoy hasn't had contact with Voldie...

I would also agree that it is because of the grudge against the Weasley family.

i agree with that and

that.
of course he hated the Weasleys and he wanted Mr. Weasley to be fired.
he also wanted something bad to happen to them.
and he needed to get rid of anything that could connect him to the dark lord so it wasnt in his house.

i mean he couldn't have known it was a horcrux.
nobody knew voldemort had made horcruxes. well except for Dumbledore, i guess.
but is that really the only reason he put it in Ginny's cauldron?
i know he didnt even kno or believe that voldemort was back, but why not just throw it away?
i know he hated the Weasleys and stuff, but he must have known it was gonna do something like open the chamber..right?
idk..it just all seems a little weird.

i guess he just hated the Wealseys and needed to get rid of the book.

The diary which happened to be Voldemort's horcrux had no choice but to use Ginny's body since It was Ginny who had opened up and shared her secrets with Riddle.

Riddle didnt choose Ginny, Lucius did at Diagon Alley when they were shopping for their school supplies, in the book store. Riddle just used her when he found out that she new Harry Potter.