Chapter 4/25- Atom

Aristotle

"father of alcomy" said there was no such thing as atoms. Instead, everything was made up of the four basic elements: air, earth, fire, and water.

Democritus

A natural philospher who claimed everything was made up of atoms

James Chadwick

Discovered the neutron

E. Goldstein

Discovered the proton using the cathode ray tube

Ernest Rutherford

Gold foil experiment

atomic mass

Number of protons and neutrons

atomic theory

a theory that states : 1) all matter is composed of tiny particles called atoms 2) atoms can't be subdivided, created or destroyed 3) atoms of 1 element are unique and different forms of same identical element 4) atoms can be combined or rearanged in chemical reactions 5)elements of different compunds combine in simple whole number ratios

Robert Milliton

discovered atomic nucleus using the oil drop expieriment

Antoine Lavoisier

law of conservation of mass/matter- matter is not created or destroyed, so a substances mass remains the same after a conversion.

J. Proust

law of definite proportions- every chemical compund has a set composition. Ex: water is always H2O

J. Dalton

law of multiple proportions- if two elements can make more than 1 compound, they will always combine in the ratio of small whole numbers

atomic number

number of protons

proton # = electron # unless...

the superscript reads something else. #+ means positivee charge, #- means negative charge

JJ Thomson

used the cathode ray tube to discover electrons