I think the best place to START science is in nature study. Once children have the basic idea of observation and classification down, then is a good time to start more formal studies of subjects like chemistry. Charlotte Mason's students most certainly DID to chemistry and physical science as well as developing biological studies. It's important to realize that nature study is a vast field; there is a LOT more going on than sketching wildflowers. Nature study can include getting muddy, investigating the little critters in the water, under rocks, etc. Many boys do kind of object to the civilized "Let's all look at butterflies and flowers" idea of nature study. I think we've "feminized" it a little, inadvertently, us homeschool moms. We think nature study should look very Edwardian-Lady. Twenty-first-century all-boy is OK too. Some places to look that might interest your son--try looking at the Discovering Nature series on Amazon; they are by different authors.
And you most certainly CAN investigate more other hands-on things. You can do this by doing BOTH nature study AND another study such as chemistry. OR you can just get some experiment books or websites and do those, especially at times you can't get outdoors as easily or as long if you live in a seasonal area. We in our own home tend to do only nature study and occasional household experiment books until around 3rd grade or so, and then we do a homeschool series like God's Design in addition to nature study.
Another thing we do for nature study that I've seen tempt many boys is geocaching.
Busy morning here, I have to run, but if you have any questions about anything I said you can ask here or PM me!