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Unformatted text preview: Atoms, Molecules and Ions • Atomic Theory- Proposed by an English Scientist named John Dalton- Composed of four hypothesis 1. Every element is composed of atoms 2. All atoms of a given element are identical, having the same size mass and chemical properties. Different elements have different atoms (law of definite proportions) 3. Compounds contain a fixed number of atoms from different elements (law of multiple proportions) 4. Chemical reactions involve only the separation, combination, or rearrangement of ato It does not result in creation or destruction. (law of conservation of mass) . 5 • / Radioactivity Radiation- Radiation The emission and transmission of energy through space in the form of waves-- X Rays Highly energetic radiation that can penetrate matter, darken covered photographic plates and causes a variety of substances to fluoresce. - ( ) Called X rays because of their unknown nature Wilhelm Röntgen • Atom- Smallest part of an element that can enter a chemical reaction- Made of three smaller particles ( + Proton p ) o Discovered by physicist Ernest Rutherford o Positive charge o 1 atomic mass unit o ( ) = Atomic number Z number of protons o Concentrated in the nucleus ( - Electron e ) o Negatively charged o No mass o ( ) Concentrated outside the nucleus surround it ( Neutron n0 ) o Discovered by physicist James Chadwick o ( ) No charge neutral o Located in the nucleus o (~ ) Mass is slightly greater than proton 1 atomic mass unit- ( ) Atomic mass A Sum of protons and neutrons 612 C = ( ) = 12 Atomic Mass A 6 Atomic ( ) Number Z- Number of protons is the same as the number of electrons only if the element is neutral- Shells and Energy Levels 1 st Shell 2 electrons 2 nd Shell 8 electrons 3 rd Shell 8 electrons 4 th Shell 10 electrons- Valence Electrons ( ) The outer electrons of an atom last shell Involved in chemical bonding...
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This note was uploaded on 06/29/2008 for the course INORGANIC 132 taught by Professor Duffner during the Spring '08 term at Molloy.
- Spring '08