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Transcript of The atom
You can barely see it.
Real electrons can move almost as fast as light.
~ 300,000,000 m/s Small mass in a large volume = low density The electron cloud is mostly empty space!! They are about 0.06% of the total mass of an atom! The cloud has layers, like an onion. There are 7 layers or shells.
Each layer is called an orbital.
Protons Neutrons Electrons move in each orbital, like a planet circling the sun Unlike planets- more than 1 electron can fit into each orbital See how there are multiple electrons in the layer. Here are 2 atoms.
What do you see? We use this table to organize them It is number of electrons that give elements their chemical properties. 1st shell: 2 electrons
2nd shell: 8 electrons
all other shells: 8 electrons I am teaching you a simplified model.
You will learn the real model in a full chemistry class. We won't go beyond the 3rd layer in my class. They are hard to see because they are so small. Moving electrons make electricity. The nucleus is in the center of the atom It has 2 types of particles:
neutrons It is tightly packed and heavy It is very dense Protons are found in the nucleus. They are large and heavy. Elements are defined by the number of protons Change the amount of protons and you change the element:
This happens in radioactive substances. They lose protons and become a different element. Protons have positive charges.
So the nucleus is positive Protons determine the atomic number of an element. #protons= #electrons + = - Overall atoms have zero charge!!! 117 has not been discovered yet, but they think it exists Neutrons are also in the nucleus. They are about the same size as a proton:
large and heavy They have no charge: neutral + #neutrons= atomic mass #protons Neutrons are only sometimes equal to protons and electrons Protons are used by your cells to create energy. To find # of neutrons :
atomic mass - atomic number Neutrons are also involved in radioactivity.
Without them we wouldn't have x-rays at the doctor. There are 118 different atoms:
each with a different amount of protons, electrons and neutrons.