When was the next really important breakthrough in the theory of matter?

The next important breakthrough was in 1802; this is when Dalton restored the study of matter with his Atomic theory. His theory stated that atoms are the fundamentals of nature and can only combine in whole number ratios.
HOPE THIS HELPED :)

False, as a substance changes from a solid to a liquid and from a liquid to a gas the molecules get farther apart from each other

Ametal with a large number of free flowing electrons most likely has good conductivity