Physical Geology Chapter 4

Matter Anything that has mass and volume Elements = simplest stable form of matter Made of atoms Compounds = chemically combined elements Made of molecules Elements:atoms::compounds:molecules

98% of crust is 8 elements and their compounds

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 grams. Employing this value, the masses of the fundamental particles of an atom have been determined to be: (1) Proton mass: amu. (2) Neutron mass: amu. (3) Electron mass: amu.

= atomic number

= atomic mass

Forms of the same element Differ in # of neutrons Same atomic number but different atomic mass (heavier) Similar behavior with some different properties Leads to average atomic mass H = amu

Ions

Valence electrons create behaviors/properties and establish periodic groups on table

Metals have 1-3 valence electrons and lose them easily Non-metals have 4-7 electrons and tend to gather more

Mendeleev’s Table

2 and 8 electrons create unreactive state (Happy) Is this important?

How do they become “happy”? Chemical bonding!

Ionic bond – giving/taking e-

Covalent bond – sharing e-

Polar covalent molecule + _

Mixtures Unlike a compound, the components are not chemically combined, just physically combined Heterogenous – not equally mixed Homogenous – “solution” and equally mixed