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chap2 Matter and Atomic Structure 2.1 Basic Concepts of Matter Matter : definition : something has mass and occupies space Exists in form element (one substance) & compound (two substance) Exists in three state (solid/liquid/gas) Solid Liquid Gas Particle Closely packed and orderly manner Closely packed not orderly manner Far apart not orderly manner Kinetic energy of particle low medium high Attraction force strong medium weak Melting Point and Freezing Point chap2 Matter and Atomic Structure 1 Melting Point: definition : a certain temperature for substance turn from solid to liquid state eg: ice to water 0°C Freezing Point: definition : a certain temperature for substance turn from liquid to solid state eg: water to ice 0°C heat energy absorbed by the particles is uesd to overcome the attraction force between the particles until solid changes to liquid. heat energy that is lost to the surrondings is balanced by the heat energy released when the particles attract each other to form solid. 2.2 The Development of the Atomic Model Subatomic particles: type (proton/neutron/electron) Symbol Relative charge Relative mass proton p +1 1 neutron n 0 1 electron e -1 1/1840 Development of Atomic Structure Model Name What did he discover? John Dalton atoms JJ Thomson electrons chap2 Matter and Atomic Structure 2 Ernest Rutherford protons Niels Bohr shells James Chadwick neutrons TIPS Dalton sits Thomas train to Rutherford. Suddenly, Boom! (Bohr) he dick disappeared. 2.3 Atomic Structure Nucleon Number = Number of proton + Number of neutron Number of proton = Proton number eg : proton number of carbon is 6 different atom different proton number Number of neutron = Neutron number eg: neutron number of atom is neutral when no of electron = no of proton Standard Representation of an Atoms 2.4 Isotopes definition: element that have same proton number but different nucleon number chap2 Matter and Atomic Structure 3 have different mass Relative atomic mass of Isotopes Uses 1. cobalt-60 : treat cancer 2. iodine-131 : treatment of tyhroid 3. carbon-14 : determine the fossils age 4. hydrogen-3 : detector study sewage and liquid wastes chap2 Matter and Atomic Structure 4