Download Intro to Element Note Answers

“Introduction to the Elements” Video Note-taking Guide
Aristotle vs. Democritus views on matter in 400BC
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Aristotle- a Greek philosopher who thought…
Everything is made up of 4 elements (earth, fire, air and water)
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Democritus- a Greek philosopher who thought…
Everything was made of atoms
o Atomos means… can’t be divided
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Whose idea is closer to what we believe today? Democritus
Whose idea was widely accepted for ~2000 years? Aristotle
Alchemists were early chemists whose mean focus was … to turn Pb to Au (change one element into another)
Elements are … the building blocks of matter, basic substances that can’t be broken down by ordinary
chemical changes
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Number of naturally occurring elements : 92
Number of elements: 112
All are listed on the … Periodic table (blue: man made black: natural)
History of atomic theory
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1808 John Dalton’s Atomic Theory based on Democritus’ early ideas
1. Tiny particles….. that could not be divided
2. Each element…. Has its own kind of atom
 Model is sometimes called the billiard ball model
1897 JJ Thomson discovered the first subatomic particle… electron
 Sketch his model
think of it looking like a chocolate chip cookie
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1911
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Ernest Rutherford famous Gold Foil Experiment
Most particles… passed right through the gold foil
4/10,000 particles… bounced back off the foil
He concluded that … atoms are made mostly up of empty space with a tiny nucleus that has a
positive charge
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Sketch his model
think of it being kind of like the inside of a peach
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1913 Niels Bohr model is called a planetary model because… electrons orbit the nucleus like planets
orbit the sun
 Energy levels around the nucleus contain.. electrons
Modern Atomic Theory
 Our current atomic model is … the electron cloud model
 It’s called the Electron Cloud model because… the electrons travel