Download Awesome Atoms and Elements

Awesome Atoms and
Elements
Chapter 3 Section 1
What is Matter?
• Anything that has mass and takes up space
• Cannot be created or destroyed – Law of
Conservation of Matter
Matter
Not Matter
Why Atoms???
• Everything that has mass and takes up
space (all matter) is made up of atoms
• YES EVERYTHING!!
• So…it helps us if we can fully understand
what atoms are and how they behave
– Have better technology
– Live longer
– Understand the universe
– Make cool stuff
Atomic Structure
• Atoms are the smallest piece of matter that still
retains the property of the element
• That means that once you split a gold atom, it is no
longer gold
• Atoms are made up of three atomic particles
– Protons (charge 1+) Found in nucleus
– Neutrons ( charge 0) Found in nucleus
– Electrons (charge 1-) Found orbiting the nucleus
Element Name
Atomic Number
=‘s the number of protons in the atom
Defines the element
Usually =‘s the number of electrons
Element Symbol
Atomic Mass
Generally =‘s the number of protons + neutrons
It is not exact on the periodic table b/c it is an average
Isotopes
• Isotopes of an element have different
numbers of neutrons
• Isotopes of an element also have different
masses
• Some isotopes are radioactive
– Carbon-14
– Hydrogen-3
• Other than that, they have the same
properties as the element
Atomic History - General
• Scientists have theorized about what an
atom is made up of since the Roman Empire
(400B.C)
• When new information is learned about the
atom, the accepted atomic model is
changed.
• Our current model of the atom is called the
Electron Cloud Model
Atomic History - Details
• Democritus was the first to NAME the smallest particle of
matter the “atom”
• Aristotle then said that all matter was only made of 4 basic
things: earth, water, air, and fire (boy, was he wrong)
John Dalton
• 1800 -Dalton proposed a modern atomic model
based on experimentation not on pure reason.
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All matter is made of atoms.
Atoms of an element are identical.
Each element has different atoms.
Atoms of different elements combine in
constant ratios to form compounds.
• Atoms are rearranged in reactions.
• His ideas account for the law of conservation of mass
(atoms are neither created nor destroyed) and the law
of constant composition (elements combine in fixed
ratios).
1) Dalton’s “Billiard ball” model (1800-1900)
Atoms are solid and indivisible.
2) Thompson “Plum pudding” model (1900)
Cathode ray experiment showed Negative
electrons in a positive framework.
3) The Rutherford model (around 1910)
Foil experiment showed that atoms are
mostly empty space.
Negative electrons orbit a positive nucleus.
• Niels Bohr realized that the electrons
are not in the nucleus, and theorized
that the electrons orbit
• Current scientists now believe that the
electrons are NOT in orbits, but move
around in an “electron cloud”
Vocabulary
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Matter
Atom
Law of conservation of matter
Electron
Nucleus
Neutron
Proton