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Download Chapter 2 Matter is Made up of Atoms
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Chapter 2 Matter is Made up of Atoms Vocab Section 2.1 Atom Atomic Theory Hypothesis Theory Scientific Law Electron Proton Isotope Neutron Nucleus Atomic Number Mass Number Section 2.2 Electromagnetic Spectrum Valence Electron Lewis Dot Diagram The Scientific Method Broken down into 5 Steps Observation Hypothesis Experiment Theory Scientific Law Observation What would happen if I lit Mr. T on Fire? Hypothesis If I light Mr. T on fire, he will be upset with me! Experiment Let’s Light Mr. T on Fire! Experiment Yep…He’s Mad! Theory I wonder if Mr. T would be upset if other people lit him on fire as well??? Scientific Law Once the experiment is tested by many people without the hypothesis changing, the theory becomes a Scientific Law (Like Gravity) The Atom John Dalton first proposed the atom He gave 3 statements about atoms Dalton 1) All matter is made up of atoms Dalton 2) Atoms are indestructble Law of conservation of matter– you cannot create nor destroy matter Dalton 3) Atoms of one element are alike, but different from other elements The Electron J.J. Thomson next proposed the electron He used a cathode ray tube to prove its existence Protons and Neutrons Ernest Rutherford later discovered protons and neutrons Protons and Neutrons He found these to be in the nucleus using the gold foil experiment Where do we find these subatomic particles? Electrons Protons and Neutrons How Small is the Nucleus? What about Masses? Particle Symbol Charge Mass # Proton p+ 1+ 1 Neutron n0 No Charge 1 Electron e- 1- 0 Atomic Number 1 H Element Hydrogen Atomic Mass 1.0079 Atomic Number = Number of Protons and Electrons! Finding Mass Number Mass number is similar to atomic number #p+ + #no = Mass Number Remember, p+ = atomic number Example Find the number of protons, neutrons, and electrons in Sodium (Na). The mass number for our sodium atom is 25. Note – we can also write this Na-25 Mass # vs Atomic # The atomic number is the average mass of all of the isotopes of a particular atom. Think Critically Why don’t electrons add to the atomic number or mass number of an element? Electromagnetic radiation Waves are given off by radiation Short waves have a high frequency Long waves have a low frequency Electromagnetic spectrum Electrons getting excited Electrons also can get excited and let off energy This will result in the electron giving off a color
