20. which of these best describes the particle motion taking place as gas is exposed to freezing...
TRANSCRIPT
Historical Models
20. Which of these best describes the particle motion taking place as gas is exposed to freezing temperatures?◦ A) The particles decrease in speed.◦ B) The particles move with more force.◦ C) The motion of the particles becomes
random.◦ D) The motion of the particles is unchanged.
21. Which of these substances is an element?◦ F) Steel◦ G) Chlorine◦ H) Plastic◦ J) Sugar
Science Starter
Molecule 1
Molecule 2
Molecule 3
Molecule 4 (can you make more?)
Total number of molecules you can make
Hydrogen Atoms only
Hydrogen and Oxygen
Carbon and Hydrogen
Draw a chart in your lab notebook
All matter is made up of individual particles called atoms, which cannot be divided.
All elements are composed of atoms. All atoms of the same element have the
same mass, and atoms of different elements have different masses.
Compounds contain atoms of more than one element.
In a particular compound, atoms of different elements always combine in the same way.
John Dalton’s Atomic Theory
A representation of something
Ex. The tennis balls of science◦ What do they represent?◦ Are they actually what they represent?◦ Usually a simplified version of something complex
What is a model?
Small Solid Spherical Indivisible
Dalton’s Atomic Model
Positive and Negative Charges are dispersed throughout the atom
Atoms have charge Electrons are stuck
in the atom like raisins are stuck in a bowl of plum pudding
JJ Thomson’s Plum Pudding Model
JJ, Plum Pudding, Chocolate Chip
Ernest Rutherford In 1906 he decided
to test the plum pudding model.
He shot alpha particles at gold foil. ◦ Some passed through
the “empty” space outside the nucleus
◦ Some bounced off the nucleus of the atom and back at the screen
Dense, positively charged nucleus
Empty space for most of atom
Peach Pit Model (Rutherford)
Dense nucleus Electrons are found
in distinct energy levels that are only found a specific distance from the nucleus
Bohr Model
Dense nucleus Space outside
nucleus where electrons are most likely to be found
Do NOT follow fixed paths like in the Bohr Model
“Fan” Model
Modern Atomic Model