Valley of Ashes represents moral and social decay. This symbol is important to the chapter because it shows the pain and troubles of the poor.
Gatsby's house represents what Gatsby does for Daisy, for instance, the parties are for her and the things he buys are to impress her, but it's much more than that. This symbol is important because depending on Gatsby's emotion the house will change.
Gatsby's house parties represent what he does to try to get Daisy's attention but sadly never works but random people that weren't invited would show up to them and no one ever knew who Gatsby was.
The yellow car is very important on many other occasions and the car belongs to Jay Gatsby. The yellow car represents the American dream for Gatsby.
The clock represents all the five years that Gatsby has been waiting to see Daisy has finally come to an end. Gatsby knocked over the clock to end time that was wasted.
Don Cody was very imporant to Gatsby he was like a father to him, Don Cody made Gatsby into a man he wanted to be. He was Gatsby's role model, Don Cody left him some money when he died but he never got it.