(by the way it has to be under 500 words)
word count = 180
^While some can achieve a strong creative essay in less than 200 words most of us mortals cannot. I suggest you use the remaining 320 words to add an in depth example of how your love for chemistry came about.
I later realized that chemistry is everywhere and is related to many other sciences.
^Really now...
My interest in science continued throughout my life and now I plan on majoring in chemistry.
When I took chemistry I became increasingly interested in it.
My interest in science started when I was a child.
My first few years of high school I wasn't interested in any particular subject over another.
I am interested in chemistry because I enjoy learning how things work at the molecular level.
"Having a degree in chemistry would help me get a job that I enjoy."
^I thought you were going to write "Having a degree in chemistry would help me get a job that I am interested in"
"A college degree will open many new doors for me, allowing me to have many choices in life. It will also help me participate in medicinal research to save lives, and get into graduate school to attain a Ph.D. "
^You have already chosen chemistry though so why do you care if you have other choices. Ph.D? That's like..I want to turn 18 so that I can turn 19 to attain 20 years of age.