CHEM 130 Chapter Notes - Chapter 2: Hans Geiger, Metalloid, Carbon-12
Document Summary
Atom- smallest quantity of matter that still retains the properties of matter. Element- a substance that cannot be broken down into two or more simpler substances by any means. Concept of the atom was first proposed by philosopher democritus in 5th century. Atoms, which all matter consists, are tiny, indivisible particles. Found that atoms are not indivisible and that they are made of up small subatomic particles. Nature, number, and arrangement of subatomic particles determine the properties of atom, in turn determine the properties of all things material. Series of investigations beginning in the middle of the 19th century indicated that atoms are made up of even smaller things. 1800, scientists were doing research involving radiation- emission and transmission of energy in the form of waves. One of many devices used was the cathode ray tube. Consists of two metal plates sealed inside a glass tube from which most of the air has been evacuated.
