CH.2 - 8.23.07 CH.2 The basic unit of matter is the atom...

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8.23.07 CH.2 The basic unit of matter is the atom -atoms are composed of protons, neutrons, and electrons electrons - very little mass # of protons= # of electrons 9except in ions) #of neutrons can vary Element - a substance that cannot be reduced to a simpler substance - elements are defined by the # of protons in the nucleus= atomic # composition of the earth Human Body Oxygen- 50% oxygen- 65% Silicon- 26% Carbon- 18% Aluminum- 8% Hydrogen- 10% Iron- 5% pther- 7% Calcium- 3% Isotopes - forms a single elemnt that differ in the # of neutrons ex. Carbon c12= 6 prtons = 6 nuetrons C13+ 6 prtons+ 7 nuetrons C14+ 6 protons+ 8 nuetrons Radio Isotopes -An isotope that has an unstable nucleus, and when a neutron is lost from an atom then energy is given of = radioactive energy -Electrons occur in shells -Each atom seek to fill its outer shell -The first shell is stable with two electrons, all other shells with eight electrons Atoms will form bonds to satisfy the requirements of their outer shells. Molecule- the number of atoms in a defined spatial relationship
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CH.2 - 8.23.07 CH.2 The basic unit of matter is the atom...

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