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Atoms
Goal of the class
• To introduce matter and discuss how it
can be classified and what it’s made up of.
• Question of the day: What are the three
main components of atoms?
Atoms
• All matter is made of atoms
– Atoms are the smallest units of matter with
unique properties
– Atoms are made of three different types
subatomic particles: protons, electrons, and
neutrons
Atomic Size
• Atoms are about 100 picometers (10-10
meters)
– Too small to reflect visible light (no color)
– Can only be seen with an electron microscope
• If an atom was the size of an orange, then an
orange would be the size of the earth.
Atomic Size
World’s Smallest Movie
http://www.ibm.com/madewithatoms
Atomic Mass
• The subatomic particles within an atom have
the following masses:
Proton
Neutron
Electron
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• Electrons have much less mass than protons
or neutrons.
Atomic Composition
• Atoms are made up of a nucleus and the electron
cloud around it
– Atoms are mostly empty space
– The nucleus is very small, has all protons and neutrons
– Electrons occupy specific regions of the electron cloud
Electromagnetic Force
• The different parts have different
electromagnetic charge
– The charge of electrons act similar to magnets
– Opposite charges attract while like charges repel
each other.
• Protons have a positive charge
• Electrons have a negative charge
• Neutrons have no charge
Atom Charges
• If an atom has more protons than electrons it
will have a positive charge
• If an atom has less protons than electrons it will
have a negative charge.
• If the number of electrons and protons are the
same the atom is neutral.
Matter’s Properties
• An atom’s properties will be determined by the
number of subatomic particles
– Example: The number of protons and neutrons will
determine the mass of an atom
– The number of protons and electrons will
determine reactivity, or cohesion
New Seating Plan
Projector
Peter
Eric Kim
Chris
Brian
Mark
Hareem
Sophia
Alex
Daniel Ha
Joseph
Gloria
Jiin
Eric Kang
Miguel
Phillip
Danny
Jun
Ryan
Vocabulary
• Subatomic – relating to particles smaller
than atoms (electron, neutron, proton).
• Electromagnetic – a fundamental force
that is a combination of electrical and
magnetic forces
• Neutral – Atoms that contain the same
number of protons as electrons
Homework
• Please read Chemical Building Blocks
pages 76-77
• Please complete Chemical Building Blocks
workbook page 33-34
• Play with
http://phet.colorado.edu/en/simulation/
build-an-atom