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Intro to Atoms!
Transcript of Intro to Atoms!
what are atoms?
Atoms are the basic building blocks of everything that exists AKA all matter!
what are atoms made of?
Atoms are made of even smaller particles: protons, neutrons, and electrons.
positively-charged (+) particles
part of an atom's nucleus
part of atom's nucleus
negatively-charged (-) particles
found in electron clouds around nucleus
Atoms with different amounts of protons, neutrons, and electrons make up different elements.
Adding a proton to an existing atom makes a new kind of atom.
Adding a neutron to an existing atom makes a new isotope of that atom.
All atoms of the same element are exactly the same.
atoms of elements
All elements are made up of thousands of atoms that are exactly alike.
Elements are pure substances; they are not made of anything except the atoms that are within them.
An element is a pure substance that cannot be separated into simpler substances by physical or chemical means.
The periodic table is a table that lists all of the known elements.
the periodic table
Example: The symbol of the element iron is Fe.
The periodic table is organized in order of lowest to greatest atomic number. There are also other ways atoms are involved in the table:
atoms in the table
On the periodic table, each element is given a name, which is usually one to three letters long.
The table is organized so each box tells us the number of protons, electrons, and neutrons in each atom via atomic mass and number.
: The atomic number is equal to the number of protons.
: The atomic number is equal to the number of electrons.
: The atomic number subtracted from the atomic mass is equal to the number of neutrons.
Wondered about breaking matter in half until it could no longer be broken
Called basic matter particles "atoms"
Atomic theories were dismissed as worthless by other Greek philosophers
Performed chemical experiments that revealed that atoms consisted of lumpy particles
Did not know about structure, but theorized about atomic properties
Elements made of atoms
Same-element atoms are exactly alike
Different-element atoms are different
Atoms cannot be cut, made, or destroyed
Joining atoms results in compounds
In chemical reactions, atoms change
J. J. Thomson
Proposed model for atom:
Known as "plum pudding" model; looked like electron raisins stuck in positive pudding
Atoms not only emit photons (light particles) but may also absorb them
Wrote paper explaining how light absorption can free electrons from within atoms: the "photoelectric" effect
Received Nobel Prize in 1921 for work on photoelectric effect
wanted to investigate inner structure of atoms by bombarding them with alpha rays (positively charged particles)
shined radium alpha rays onto a gold screen; results were highly informative
reasoned that particles that veered from foil must be scattered by positive particles; made theories about electrons
devised experiments based on two rules:
1: electrons can only orbit in clearly defined distances from the nucleus
2: atoms absorb and radiate energy when electrons move throughout orbits
teamed up with scientist Arnold Sommerfeld to expand original Bohr model
discovered that electrons travel in orbits with different shapes, and orbits could be tilted by a magnetic field
Schrodinger tried to form an atomic model based off particle waves.
Heisenberg used a theory called matrix mechanics to explain the behavior of atoms.
While both theories operated on completely different assumptions, they both appeared to be correct and were mathematically identical.
found particle slightly heavier than proton, with no charge
the proton-neutron in the center eventually earned the name "nucleon"- soon to be "nucleus"
Dirac and Anderson
Dirac discovered the positively-charged electron
He didn't believe his own theory at first
Anderson discovered a negatively-charged proton during his experiments with cosmic rays
General term is antimatter, explodes when comes in contact with matter
Elements have their own chemical properties too!
what is an element?
( It's essentially a heavier version of that atom! )
what keeps atoms together?
Electrons are kept in orbit by their attraction to the protons in the nucleus.
Protons are kept from repelling each other due to electromagnetic force by a force called STRONG FORCE.
Strong Force holds the nucleus together.
non-charged (0) neutral particles
Atoms come from the Greek word atomos, which means "indivisible", or "uncuttable".
An atom is the basic unit of matter, and is the smallest particle into which an element can be divided.
When an atom is split (which is very difficult to do) a massive amount of energy is produced.
This energy is called atomic energy.
Atomic energy can be used to help society. However, it can also be used for extremely destructive purposes.
One of the first well-known uses of the atom bomb was not to better the world, but to cause destruction.
The United States of America dropped two atomic bombs on the Japanese cities of Hiroshima and Nagasaki in retaliation for the nation's bombing of Pearl Harbor.
The cities were devastated. Hundreds of thousands of people died instantly, and even more were left ill.
Atomic energy can be used for beneficial purposes.
It can be a source of power for many different kinds of machines and operations.
A few countries have ships and submarines that run on atomic energy.
Many have nuclear power plants that generate atomic energy on a very large scale to power nearby towns, cities, etc.
Scientists are also trying to find ways to use atomic energy as a source of fuel, treatment, and pesticides.
Atomic weapons, also known as nuclear weapons, derive enormous amounts of energy from relatively small amounts of matter.
Nuclear weapons get their energy from a combination of fission and fusion.
atoms make up matter, which makes up all things
different atomic structures create different elements, or pure substances
atoms consist of positively (proton) and neutrally (neutron) charged particles in the center (nucleus), orbited by negatively charged particles (electrons)
scientists have spent a very long time coming to today's understanding of atomic workings
atomic energy can be used both positively and negatively
Walker, Jim. "Atoms." Web. 6 May 2012. <http://www.nobeliefs.com/atom.htm>.
"What Are The Uses Of Atomic Energy?" Blurtit. Web. 02 May 2012. <http://www.blurtit.com/q675045.html>.
"All About Atoms - What Are Atoms?" All About Atoms - What Are Atoms? Web. 07 May 2012. <http://education.jlab.org/atomtour/>.
"Atoms Around Us." Chem4Kids.com: Atoms. Web. 29 April 2012. <http://www.chem4kids.com/files/atom_intro.html>.
"Structure of the Atom." Structure of the Atom. Web. 30 Apr. 2012. <http://www.nyu.edu/pages/mathmol/textbook/atoms.html>.
"Atomic Structure." Atomic Structure. Web. 01 May 2012. <http://web.jjay.cuny.edu/~acarpi/NSC/3-atoms.htm>.
"Atomic Structure Timeline." Atomic Structure Timeline. Web. 28 May 2012. <http://atomictimeline.net/index.php>.
"Home of the Periodic Table." WebElements Periodic Table of the Elements. Web. 03 May 2012. <http://www.webelements.com/>.
"Exotic Sub-Atomic Particles." Particles. Web. 10 May 2012. <http://www.whillyard.com/science-pages/exotic-particles.html>.
"Atomic Bonding." Atomic Bonding. Web. 01 May 2012. <http://web.jjay.cuny.edu/~acarpi/NSC/5-bonds.htm>.
How Small Are Atoms Really?
The notes that you need to write are in red.
Write all of them down.
Examples will be written in purple.
You don't have to write the examples,
but it will help you understand the vocabulary.
Write the examples if you need a little help understanding the concepts
Don't worry about writing anything in black.
center of the atom
home of the protons and neutrons
the electron cloud
surrounds the nucleus of an atom.
Size determines the size of the atom.
ELECTROMAGNETIC FORCE- LIKE CHARGES Repel each other, while OPPOSITES ATTRACT each other.
GRAVITATIONAL FORCE - The force of gravity is small within Atoms because of their small size.