Matter describes anything that has mass and volume Can matter be invisible YES Ex Air Matter and Atoms History of atoms Democritus Was a Greek philosopher in 400 BC Thought the universe was made of ID: 749451
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Slide1
Unit 2 Atomic Structure and MatterSlide2
Matter describes anything that has mass and volume
Can matter be invisible?
YESEx. Air
Matter and AtomsSlide3
History of atoms
Democritus
Was a
Greek philosopher in
400 BC
Thought the universe was made of
atoms
and empty spaceATOM comes from the Greek word atomos, which means cannot be dividedSlide4
Antoine Lavoisier
Was a
French
chemist in the late
1700’s
Lavoisier
proved that matter cannot be created or destroyed during chemical changes like burning or rusting
The principle is called The Law of Conservation of MatterSlide5
Joseph Proust
Was a
French
chemistHe stated that the basic building blocks of a
substance
are always in the
same wayFor example every molecule of water is made of 2 hydrogen atoms and 1
oxygen atom (H2O)Slide6
Models of the Atom
What is a model
?
A model is anything that lets you create an image
in your mind of something that is too
big
, too
small or too complex to understand otherwiseModels can also be used to study events that happen too fast or too
slow or would be too dangerous
to study otherwiseSlide7
John Dalton’s Atomic Model
Dalton was an
English
chemistIn
1803
, he proposed that atoms of the
same
element are the same and atoms of different elements are differentFor example, a piece of lead is made up of only
lead atoms
He also stated that
atoms
are the smallest particle of matter.Slide8
Atoms are too small to see with the human
eye
We need models to help us understand what they look likeModels are not completely
accurate. They represent something that is not easily seen or understood
Atomic ModelsSlide9
Atomic Structure
The Nucleus
Is the center of the atom
99.9% of an atom’s mass is in the nucleus
The nucleus is made of
protons
and
neutronsProtons have a positive chargeNeutrons have no chargeWhat charge does the nucleus have?
PositiveSlide10
Around the nucleus the electrons fly around in random patternsAn electron has an
negative
chargeAn atom has equal numbers of protons and
electrons
The Electron CloudSlide11
Electron Cloud
An electron is about
1800 times lighter than a proton or a neutron
Electrons can easily be lost because they are far away from the nucleus.
Have
you ever rubbed a balloon on your head? Have you ever zapped your little brother?