Chemisty Chapter 2
Terms
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who was Democritus?
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greek phiosopher
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what did Democritus propose?
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that all matter, the stuff that makes up the world around us, is actually composed of tiny, invisible particles.
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what did Democritus call these tiny particles?
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atomos
or atoms
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what did Aristotle come up with
what were they?
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4 elements
fire= hot
earth= cool/heavy
air=light
water=wet
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Who was right?
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since Aristotle was more famous he won
and his ideas carried through the middle ages.
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John Dalton
where was he from?
what was his job?
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England
Teacher
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What did Dalton come up with?
what was it?
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Dalton's Atomic Theory
combined ideas
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what are the 4 main postulates of this theory?
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all matter is made of tiny invisable particles calld atoms
atoms of the same elemnt are identical ... different elsments are different.
different elements combined in whole number ratios form a compound.
chemical re
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what did Ben Franklin do?
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made electricity
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+/-
+/+
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attract
repel
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what did Michael Faraday do?
what did he "invent"
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showed electricity in an atom
battery
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What is Faraday the father of
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electrochemistry
- what is a cathode Ray Tube?
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glass tube that has been evacuated of air
it has charged plates on wither end of the tub.
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what side of cathode ray tube is positve
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cathode side
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what side of the cathode ray tube is negative
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anode side
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J.J Thomson
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had the gas dischraged tube to show they were made up of egaive charged particles
he measured how the cathode rays wer deflected
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what is a particle
and who discovered it?
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electons
J.J Thomson
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Robert Millikan
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h was able to dermine the charge on the electron
calculate the mass(very small)
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what is the oil drop experiment
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indirect measuring to determine the charge of the electron.
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what was Thomson model of an atom
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Plum Pudding model
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what was he plum pudding model
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lectrons were andomly spread throughour t poxitivly charged thing
aka a chocolate chip cookie
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beta
gamma
alpha
what are the charges for these?
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negative
neutral
positive
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nucleus = ?
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neutron
protons
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atomic number
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number of all the protons in an atom
id of matter
distinguishes one type of atom from another
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atomic mass
- number of protons and neutrons
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who has the decimal?
atomic mass or number
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atomic mass
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number of neutrons =______ - ______
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mass number - atomic number
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what is atomic mass?
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the weighted average mass of all the naturally occurring isotopes f an element
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what is an isotope?
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atoms of certain element
may contain different numbers of neutrons
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nucleus is what
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neutrons and protons
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what is the strong nuclear force?
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forces of attraction within particles in the nuceus
* neutrons make the nucleus "stick" together
- what is Radioactivity?
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spotanus release of energy resulting in a change in the neulcues
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alpha is _________ dangerous
how can it be stopped?
it is the result of what?
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least
it can be stopped by clothing and paper
of 2 protons and 2 neutrons leaving the nuclues
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Beta is what
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high sped stream of electrons that are leaving the nucleus
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Gamma is what
it is _______ dangerous
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highly excited forms of energy
most dangerous only lead and concrete can stop it
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what is a nuclear reaction
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reactions that change an atoms necleus
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what are the two types of reactions
- alpha decay and beta decay
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what did Michael Faraday show?
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showed the electricity in an atom
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what side of cathode ray tube is positive
- cathode
- who discovered particles -> electrons
- J.J Thomson
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by measuring how the cathode rays were deflected he realized what
J.J Thomson
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1. greater the mass, less the deflection
2. greateer the charge, the greater the deflection
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what was the oil drop experiment?
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indirect measuring to determine the charge of the electrons