Sign In

Lesson 1

Matter - Anything that has mass and takes up space
Elements - simplest pure sub
Dalton’s Atomic Theory
Greeks were very good at observing stuff, but could not prove it
Greeks knew of matter as small particles that cannot be divided, but cannot prove
In 1800s, Englishman named John Dalton saw pattern in numerical data and used that patter as evidence to develop and prove his atomic theory
Atomic theory - all atoms of the same element are identical and have the same mass,
atom of one element cannot be changed into another, atoms cannot be created or destroyed chemically, only rearranged.
Every compound has a specific ratio, cannot be different
In 1897, british scientist J.J Thomson discovered atoms contains negatively charged particles
Electron cloud
In the 1920s, the atomic model was changed again, after scientists determined that electrions do not orbit on a fixed track
Modern model
1932, James Chadwick