Atoms, Atoms, Everywhere!
By: Hayden Langham
You Will Be Learning.......
Democritus' Atomic Ideas
- Democritus believed that there was a limit to how small a grain of sand could be divided.
- Aristotle believed that a grain of sand could be divided indefinitely.
Democritus believed that atoms made up all matter.
Democritus believed that when atoms collided, they repelled each other or gathered together.
People believed Aristotle over Democritus because Aristotle was more influential.
Aristotle studied a very wide variety of science.
He did not believe in the atomic theory. He believed that all substances were made from fire, air, earth, and water.
Dalton's Atomic Model
One of Dalton's experiments was investigating the presence of gases
Dalton's atomic theory had three parts:
Bohr's Atomic Model
Bohr's model is useful because it explains the properties of different elements.
Bohr thought that electrons can move around the nucleus at a fixed distance.
Electrons with lower energy are closer to the nucleus.
An atom is like a ladder because you can only stand on the rungs, not in between.
Mendeleev and the Periodic Table
Mendeleev's main job was a scientist.
He decided to organize the elements because more and more were being discovered.
To help him work on organizing the elements he used a set of cards.
He organized the elements in order of increasing atomic mass.
Atomic mass is the mass of one atom of an element.
Mendeleev called the columns group and families.
Mendeleev called his chart the periodic table because of its repeating pattern.
The rows across in the periodic table are arranged by increasing atomic mass.
Mendeleev left spaces because those elements hadn't been discovered yet.
Why Study Atoms?
People believed Dalton because he could experiment.
We learn about Dalton's theory because he laid all the groundwork for future study of chemistry.
Dalton did not know electrons and neutrons.