science 9 - atomic theory

democritus

atomos, small hard particles

dalton

4 rules 1) atoms are tiny invisible particles 2) one element are all the same 3) different elements are different 4) compounds formed by combining atoms

thompson

discovered electrons, proposed atoms have positive charge and negative charged electrons scattered (cookie)

rutherford

discovered protons and nucleus, mostly empty space

bohr

theorized electrons orbit around nucleus, every atom has specific amount of electron shells (planet model)

modern cloud

electrons move around nucleus in a cloud, impossible to know where electron is

who organized periodic table

dimitri mendeleev, increasing atomic mass

alkail metals

most reactive, very soft, 1 valance electron

alkaline earth metals

important to plant and animal phys.

transition metals

hard+high density, high melting and boiling points

halogens

salt producers, 7 valance electrons, highly reactive

noble gasses

unreactive, full outer shells, 8 valance electrons

metalloids

inbetween metals and nonmetals, have luster but not brittle

nonmetals

solids/gasses, brittle, little to no luster, not conductive, easily gain electrons