Atomic Theory - Tri-Valley Local School District
Transcript Atomic Theory - Tri-Valley Local School District
The physical universe is made
of Matter and Energy
Energy can take many forms
but all regular matter is made
All Notes are in yellow on a blue background. The
rest is extra information I want to share with you.
FIRST IDEAS OF ATOMIC THEORY
In the 5th century BCE, Leucippus and his pupil
Democritus proposed that all matter was
composed of small indivisible particles called
atoms, in order to reconcile two conflicting
schools of thought on the nature of reality. On one
side was Heraclitus, who believed that the nature
of all existence is change. On the other side was
Parmenides, who believed instead that all change
WHAT ARE ATOMS?
Atoms are the basic building blocks of matter
that make up everyday objects. A desk, the air,
even you are made up of atoms!
Maybe the greatest scientific truth ever
discovered. There are 92 naturally occurring
kinds of atoms. Scientists in labs have been
able to make about 25 more.
(ALL THE TYPES OF ATOMS)
All atoms have:
• Negative electrons on
• Positive protons in the
And all but hydrogen
have neutral Neutrons
in the nucleus too
DALTON DISCOVERS ATOMS
Around Two hundred years ago John Dalton described
Made of only one type of atom (all found on periodic
Each type of Atom has a certain number of Protons
carbon for example has 6 protons
When ,more than one type of atom is
Together (CO2, H2O, CH4)
WHICH ARE COMPOUNDS AND
WHICH ARE ELEMENTS?
MODERN ATOMIC THEORIES
Atomic theory has progressed greatly
over the last two hundred years.
We now know the atom is divisible and
has two main areas and three main
ELECTRON (NEGATIVE CHARGE
FOUND ON THE OUTSIDE OF THE
Electrons – are found in shells on the outside of an
they have a negative charge and very little mass.
( About 1/1800
of the proton’s mass)
(PS) ELECTRONS COME IN SHELLS
Why can we say we never touch anything??
Where are electrons found? What charge do electrons have?
electrons found on the outermost shell.
These are the same in every family
Ex: Family 1 has 1
Maximum # in shells
2, 8, 18
(PS) VALENCE NUMBER
The valence number determines chemical reactivity (the types of reactions and bonds that
Elements will either gain or lose electrons to get to a stable octet (8)
Elements will take the shortest steps to get to 8, (In
Where does light come
your own words explain)
(PS) CHEMICAL FAMILIES
All vertical columns have the
same number of valence
Family 1 has 1
2 has 2
13 has 3
14 has 4
15 has 5
16 has 6
17 has 7
18 has 8
The nucleus is 10,000 times smaller than
the electron cloud.
Almost all of the mass is found here, and it
has two main parts .
Protons (1 atomic mass unit (amu) & a
Neutrons (1 amu mass, no charge)
WHAT ARE ATOMS MADE OF?
In the Nucleus of the Atom
we have both:
• Protons (1 atomic mass
unit (amu) & a positive
• Neutrons (1 amu mass,
• Outside of this orbit the
1/1826the mass of the
ATOMIC MASS & ATOMIC NUMBER
Atomic number = to proton number and is the
number that determines what the element is.
Atomic mass is equal to the number of protons
and neutrons combined
Isotopes are forms of an
element that have the
normal number of
protons, but different
numbers of neutrons (If
you change the proton number you
change the element)
THREE QUARKS FOR MUSTER MARK
(MURRAY GILLMAN TAKES A LINE FROM JAMES JOYCE’S’ “FINNEGAN’S WAKE”)
Protons and Neutrons are made of even smaller
Three quarks make up protons and neutrons
Two “up” quarks (+2/3 each) and a down (-1/3)
make a proton (+1)
Two downs and an up make a neutron
JUST A THEORY
Our understanding of atoms and atomic behavior has grown and continues to grow as
our ability to measure and test (experiment with ) the smallest particles of
existence has grown.
Our current atomic theory is the most accurate thing humans know and its still “just a
theory” In science we test our theories in every way we can.
E=MC2 (MATTER FROM ENERGY)
People have been able to create matter from energy by
slamming particles together at near the speed of
We create pressures and temperatures similar to the
COSMOS a few nanoseconds after the big bang
The Large Hadron Collider (LHC) is being built in a circular tunnel 27 km in
circumference. The tunnel is buried around 50 to 175 m. underground. It straddles
the Swiss and French borders on the outskirts of Geneva. To be completed in 2007
INCREASING FROM SMALLEST TO LARGEST WE
HAVE ATOMS, MOLECULES, CELLS, PLANETS,
SOLAR SYSTEM, UNIVERSE