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Atoms- Basic Units of Matter (Is there historical evidence of atoms (The…
Atoms-
Basic Units of Matter
What is the current atomic model?
Inside the Atom
The first atomic-force microscope was invented in the 1980's
The atom is mostly full of empty space
Parts of Atoms- Protons, Neutrons, and Electrons
Neutron- particle that contains no charge
Proton- positively charged particle in the nucleus
Nucleus- is located in the middle of the atom. contains most of the atom's mass
Electron- negatively charged particle that moves in the space around the nucleus
The Size of Atoms
An atom's protons and neutrons are packed tightly together
Protons and Neutrons have about the same mass
Matter is anything that has mass and takes up space
Atom's are very small particles that makes up all matter
Is there historical evidence of atoms
Democritus and the Atom
c. 460-370 B.C.
Believed that Atoms were indivisible
He thought that atoms were small solid spheres with no holes and no empty space inside
He wanted to be able to cut open an atom
The Law of Conservation of Mass
Antoine Lavoisier (1743-1797)
Lavoisier measured mercury into a sealed container and and heated it to see if something different would happen
Something changed instead of being red it turned into a slivery liquid. This happened because of Oxygen
He found that the total mass of the starting materials was always the same as the total mass of the products
The law of conservational mass states that the mass of the products always is the same as the mass of the starting materials
Dalton's Atomic Model
John Dalton (1766-1844)
He made symbols for the known elements
He had an atomic theory that had five principles
All matter is made up of atoms
Atoms are neither created nor destroyed in chemical reactions
Atoms of different elements combine in whole-number ratios
Each element is made of a different kind of atom.
The atoms of different elements have different masses and properties
Each time new evidence becomes available, the model of atomic structure becomes clearer and more accurate
The Law of Definite Proportions
1779 J.L. Proust analyzed a variety of pure compounds to determine their composition
Pure compounds always contain the same elements in the same proportion by mass