Presentation on theme: "Physical Geology Chapter 4. Matter Anything that has mass and volume Elements = simplest stable form of matter Made of atoms Compounds = chemically combined."— Presentation transcript:
Atomic Structure Small electrons in cloud (- charge) Much larger protons in nucleus (+ charge) Slightly larger neutrons in nucleus (0 charge) Every element unique
Common units of mass, such as grams, are much too large to conveniently describe the mass of an atomic nucleus or any of its constituent parts. To solve this problem a new unit was defined: the atomic mass unit (amu). The atomic mass unit is a relative unit defined arbitrarily by assigning a mass of 12 amu to the neutral atom carbon-12, the common isotope of carbon. One atomic mass unit equals 1.66 X 10-24 grams. Employing this value, the masses of the fundamental particles of an atom have been determined to be: (1) Proton mass: 1.00727 amu. (2) Neutron mass: 1.00867 amu. (3) Electron mass: 0.00055 amu.