Chemistry
The study of matter,
and
how matter changes.
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The Universe can be divided
into two categories:
1.
Matter: Anything having both mass &
volume

2.
Ex: your textbook, your bottle of water and
the air surrounding you
Energy: the ability to exert a force across
a distance

Ex: heat, light, electricity, motion
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4
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Mass vs. Weight
What is Mass?
 The amount of matter (# of atoms or
molecules) in an object
What is Weight?
 The effect of gravity on an object’s mass
Since we are stuck here on Earth, we usually
use mass & weight interchangeably.
http://www.nyu.edu/pages/mathmol/textbook/weightvmass.html
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Volume
What is Volume?
 The amount of space an
object occupies
 Regular geometric
shapes are easy to
determine:




Cubic volume=L w h
Sphere = (4/3) pi r 3
Pyramid = (1/3) b h
Cylinder = pi r 2 h
 Irregular
Objects
are harder:
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Observing Matter
 Qualitative


Observations
Using Touch, Taste, Smell, Sight & Hearing
Finding words to describe an object
 Quantitative



Observations
Using measurements
Finding numbers to describe an object
The flower is:



White & yellow & sticky
4 cm tall stem
3.5 cm flower diameter
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The Atom
 All
matter is composed of tiny particles
called “atoms”
 The Elements are the types of atoms we
find in the universe
 An atom is the smallest piece of an
element which still looks and behaves like
that element
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The Atomic Model
 What
 The
does an atom look like?
answer to this question has evolved
over many years…
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Democritus
460 BCE – 370 BCE
•
Ancient Greek philosopher
who proposed that if an
object was cut-in-half over
and over again, eventually
you reach a point at which
it could not be cut-in-half
anymore
•
This piece was said to be
indivisible or (ἄτομος;
“atomos”)
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John Dalton
1803
-
Matter divided into small,
indivisible atoms
Each elements made of
different atoms
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Dalton’s Billiard
Ball Model
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JJ Thomson
1897
- discovered positive/negative
charges within atom
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JJ Thomson’s
Raisin Bun Model
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Ernest Rutherford
1911
-discovered negative electron
cloud surrounding central,
positively charged nucleus
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Rutherford’s
Beehive Model
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Niels Bohr
1913
-described surrounding
electrons to be locked into
“orbits” of specific energy
levels
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Bohr’s Solar
System Model
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James Chadwick
1932
-discovers neutral neutron
among positive nucleus
-this explains mass discrepancy
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Quantum Mechanics
17 of the 29 attendees were, or became, Nobel
Prize Winners
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Quantum
Mechanical
Model
•
Zones of highest probability
of electron location
•
Not required for this course!!