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Chapter
19
Atoms
0 Matterisanythingthattakesupspaceandhasmass.
Allmatterismadeofatoms.
0 Atomsarethebasicbuildingblocksofmatter.They
makeupeverythingaroundus;Yourdesk,theboard,
yourbody,everythingismadeofatoms!
0 Atomsaretoosmalltoseewithoutpowerful
microscopes.
Structure of the Atom
1
Atomic Components
• An element is matter that is composed of one
type of atom, which is the smallest piece of
matter that still retains the property of the
element.
• Atoms are composed of particles called
protons, neutrons, and electrons.
Atomic Structure
Therearetwobasiccomponentsineveryatom:
Nucleus
ElectronCloud
Subatomic Particles
Threesubatomicparticlesmakeupeveryatom:
SubatomicParticle
Charge
Location
Proton
Positive(+)
Nucleusor“Core”
Neutron
NoCharge(0)
Nucleusor“Core”
Electron
Negative(-)
ElectronCloud,
OutsideofNucleus
Subatomic Particles
Nucleusor“Core”:
• Protonsand
Neutronsarefound
inthenucleus.
ElectronCloud:
• Electronsorbit
thenucleus.
Atomic Theory Timeline
Scientist
John
Dalton
Information
Allmatterismadeofatoms.
Atomsaretoosmalltosee,
indivisibleandindestructible.
Allatomsofagivenelement
areidentical.
Model
Atomic Theory Timeline
Scientist
J.J
Thomson
Information
Discovered the
negativeelectron,
andpredictedthat
therealsomustbe
something positive
toholdthe
electronsinplace.
Model
Atomic Theory Timeline
Scientist
J.J
Thomson
Information
Model
Discovered the
negativeelectron,
andpredictedthat
therealsomustbe
something positive
toholdthe
electronsinplace.
Hereisanotherdrawingofthesameatommodel.
Thisoneissimilartotheonepicturedinyourtextbook.
Atomic Theory Timeline
Scientist
Information
Ernest
Discovered the nucleus of
Rutherford anatomandnamedthe
positiveparticlesinthe
nucleus“protons”.
Concludedthatelectrons
arescatteredinempty
space aroundthenucleus.
Model
electrons
protons
Atomic Theory Timeline
Scientist
Information
Model
Ernest
Discovered the nucleus of
Rutherford anatomandnamedthe
positiveparticlesinthe
nucleus“protons”.
Concludedthatelectrons
arescatteredinempty
space aroundthenucleus.
Hereisanotherdrawingofthesameatommodel.
Thisoneisstraightfromyourtextbook.
Atomic Theory Timeline
Scientist
Niels Bohr
Information
Concludedthat
electronsare
locatedin
planet-like
orbits around
thenucleusin
certainenergy
levels.
Model
Atomic Theory Timeline
Scientist
Niels Bohr
Information
Model
Concludedthat
electronsare
locatedin
planet-like
orbits around
thenucleusin
certainenergy
levels.
Hereisanotherdrawingofthesameatommodel.
Thisoneisstraightfromyourtextbook.
Scientist
(ManyScientists!)
Information
Electronsdonotorbit the
The Modern
nucleusinneatplanet-like
AtomicTheory
orbitsbutmoveathigh
speedsinanelectroncloud
aroundthenucleus.
Model
Scientist
Information
(ManyScientists!)
Electronsdonotorbit the
The Modern
nucleusinneatplanet-like
AtomicTheory
orbitsbutmoveathigh
speedsinanelectroncloud
aroundthenucleus.
Hereisanotherdrawingofthe
sameatommodel.
Thisoneisstraightfromyour
textbook.
Model
Structure of the Atom
1
Atomic Components
• Protons and neutrons are found in a small positively
charged center of the atom called the nucleus that is
surrounded by a cloud containing electrons.
• Protons are particles with an electrical charge of 1+.
(+1
Structure of the Atom
1
Atomic Components
• Electrons are particles with an electrical charge of 1–.
• Neutrons are neutral particles that do not have an electrical charge.
(+1
Structure of the Atom
1
Quarks—Even Smaller Particles
• Protons and neutrons are made up of smaller particles called quarks.
(+1
(+1