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Entrance question. Answer yes or no to the following and prepare to argue your answer An atom cannot be broken down any further An atom is the same throughout An atom is made up of several different parts. Atomic Structure. Ch 4-1. Objectives. Describe what an atom is
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Entrance question • Answer yes or no to the following and prepare to argue your answer • An atom cannot be broken down any further • An atom is the same throughout • An atom is made up of several different parts
Atomic Structure Ch 4-1
Objectives • Describe what an atom is • State the charge, mass, and location of each part of an atom • Describe what valance electrons are
Atoms • The smallest part of an element that still has that’s elements unique properties • Make up ALL matter
History of the atom • In 4th century BC the atom was first theorized by Democritus • He coined the term “atom” meaning unable to divide • Skip to 1808 and John Dalton • Atoms could not be divided • All atoms of a given element are exactly alike • Atoms of different elements can combine to form compounds
Building Blocks • Atoms make up everything! • An atom is the smallest part of an element that still has that elements properties
Atoms are made of • Nucleus – central part of the atom • Protons – positive “+” charged particle • Neutrons – neutral charged particle • Electrons – negative “-” charged particle that rapidly circles the nucleus e- electron
An atom walks into the bar, asks for a drink and asks how much, the bartender replies; for you, no charge! • Why? • A balanced atom has the same number of protons as it does electrons • Same number of + and same of – equals 0 charge • **only true for unreactive atoms!**
Bohr model • Atom is similar to planets’orbits around sun • Electrons can only occupy these “shells” • A higher shell has a higher energy level • Energy is released as e- move closer to the nucleus But how does the electron get from level to level?
Think more like a cloud • The dots represent an area where the electron could be • The more dense the dots the more likely the electron is there • We can never know for sure where the electron actually is These levels are called “Energy levels”
Valance electrons • The electrons in the outermost energy level are called valance electrons • Its these electrons that give the atom its unique chemical properties