Resident Physics Lecture Weebly居民的物理课 Weebly.pptVIP

Resident Physics Lecture Christensen, Chapter 1 Radiation Physics Can Be Fun Quicky Science Review Abbreviations 109 giga G (billion) 106 mega M (million) 103 kilo K (thousand) 10-1 deci d (tenth) 10-2 centi c (hundredth) 10-3 milli m (thousandth) 10-6 micro m (millionth) 10-9 nano n (billionth) 10-12 pico p (millionth millionth) Energy Aside Kinetic Energy Energy of an object by virtue of its speed K.E. = (1/2) X mv2 m is mass v = velocity Potential Energy Energy of an object by virtue of its position What’s the Smallest Thing that is Sugar? Divide, divide, divide The smallest entity that is still sugar is the sugar molecule But What’s in that Sugar Molecule? Different color balls? No! Atoms Interesting Fact You Already Knew There are zillions of different types of molecules There are only 92 naturally occurring types of atoms Ever Seen This? Composition of the Atom Protons Neutrons Electrons Protons Positive charge Live in nucleus Neutrons No charge (free?) Live in nucleus Ever-so-slightly more mass than proton Better than oldtrons? Electrons Negative charge Found surrounding the nucleus Exist only in designated shell locations Weighs only 1/1836th as much as proton Atomic Number # protons Defines element its properties Color State Helium is helium because it has 2 protons # neutrons does not affect chemistry Atomic Weight # protons + # neutrons # nucleons A specific element often found with multiple atomic weights Always the same # protons Different # neutrons Atomic Mass Unit (amu) Nominally 1 amu = the weight of a proton or neutron Officially 1 amu = 1/12 the weight of a carbon-12 atom 6 protons 6 neutrons Atomic Symbol How Many Electrons? In a neutral atom (not negative or positive)# electrons = # protons Charge Theory Unlike charges attract Coulomb Forces Coulomb Equation Story F