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4.1 Atomic Structure I CAN: -RECALL AND DISCUSS THE EFFECT OF TECHNOLOGY ON THE CREATION OF ATOMIC MODELS AND DISCUSS HOW TECHNOLOGY INFLUENCED THE DEVELOPMENT OF PREVIOUS AND CURRENT ATOMIC MODELS (I.E. RUTHERFORD’S GOLD FOIL EXPERIMENT). -CAN RECOGNIZE THAT ASSOCIATION WITH GROUP OR FAMILY IS BASED ON SIMILAR CHEMICAL OR PHYSICAL PROPERTIES DO NOT TRUST ATOMS! THEY MAKE UP EVERYTHING! What are atoms? Tiny units that determine the properties of matter. Properties of aluminum… Greek philosopher Democritus “unable to divide” No one believed him. John Dalton developed atomic theory. 1808, the foundation was laid. Still said atoms can not be divided. Is this true? 100 years later: Protons, neutrons, and electrons discovered Atoms of given elements were exactly alike. Atoms of different elements can join to make compounds Atoms of building blocks of molecules Atom is the smallest part of an element that still has the element’s properties. Atoms join together to make molecules. For us to see it, large numbers of molecules must join. Still made of 2 H and 1 O. Atoms are made of protons, neutrons, and electrons. Nucleus: atom’s center which is made up of protons and neutrons. Proton: subatomic particle that has positive charge Neutron: subatomic particle that has no charge (neutral) Electron: subatomic particle that has a negative charge. Number of protons and electrons in an atom are unique for each element. Ex: He has be one more proton and electron than H. Unreacted atoms have no overall charge. Atoms do not have a charge Equal number of protons and electrons (charges cancel) Models of an Atom NIELS BOHR: Electrons in atom move in set paths around nucleus much like planets in orbit. FALSE! Energy levels: still thought to be true. Modern Model: electrons behave like waves on a vibrating string. An electron’s exact location cannot be determined (think fan blades) Electrons exist in energy levels (shells) The number of filled energy levels depends on the number of electrons. 2-8-8 rule Electrons are found in orbitals within energy levels. Orbital: region in an atom where there is a high probability of finding electrons. Probability of density Sublevels or sub”shells”: S=2 (one pair) P=6 (three pairs) D=10 (five pairs) F=14 (7 pairs) Review Compare to hotel… Every atom has between one and eight valence electrons. Valence electron: an electron that is found in the outermost shell of an atom that determines the atom’s chemical properties. Lewis dot diagram. Can be figured by electron configurations. Vertical group indicate how many valance electrons Rutherford's gold foil experiment https://www.youtube.com/watch?v=zUtIrO3fUgg
