Greek philosopher believed that matter is composed of atoms. He believed they were indivisible, indestructible, and homogenous. Have different sizes and shapes which determine their properties.
Atomic Theory. Matter is composed of small particles called atoms. Atoms are indivisible and indestructible. Atoms of an element are identical in size, mass, and chemical properties.
concluded that cathode rays consist of electrons. All atoms must have electrons
Experiments showing the mass of an electron. The mass of the simplest type of hydrogen. A single electron carries a charge of -1
Plum Pudding Model. Atom a uniform structure of positive charge with negative electrons to balance the positive charge without.
Gold foil experiment. Alpha particles through gold foil. SOme deflected, sme passed through. Concluded nucleus is a dense center with a positive charge surrounded by electrons.
Nuclei also contain a neutron.