Transcript 1 chemistry intro 2015

Chemistry
The Study of Matter
The Basics
• Chemistry is the study of matter and their
interactions
– The substances of which physical substances
are made
• The study of modern chemistry began in
the 1700’s
• For thousands of years prior, alchemists
were the main students of matter and
their interactions
– Alchemy was a little science mixed with a lot
of philosophy and spiritualism
Matter is classified based on its
state or phase
The 4 states/phases are:
1.
2.
3.
4.
Solid
Liquid
Gas
Plasma
Solid
Particles are:
• arranged in regular, repeating
patterns
• held firmly in place
• are vibrating
Liquid
Particles :
• Flow easily around one another
• Kept from flying apart by attractive
forces between them
Liquids assume the shape of their
container
Gas
• Particles fly around at great speeds
in all directions
• Attractive forces between particles
are insignificant
• Will completely fill its container
Plasma
• Atoms lose their electrons at high
temperatures
• A mixture of nuclei and electrons
• By far the most common state of
matter in the universe
Kinetic-Molecular Theory
• Describes solids, liquids and gases
• All matter consists of extremely
small particles
• Particles are in constant, random
motion
• The higher the temperature, the
faster the particles are moving
(more kinetic energy)
– The ‘energy of motion’
Solids
• Particles have lower kinetic energy
than liquids (move at low speeds)
• Particles are close together and
restricted to specific locations
• Particles are arranged with a high
degree of regularity
Liquids
• Particles have a higher kinetic
energy than solids (move at faster
speeds)
• Particles are close to each other but
can move past one another
Gases
• Particles have high kinetic energy
(move at high speeds)
• Particles move freely in random,
straight-line patterns
• Little interaction between particles
Plasma
• Higher energy than a gas
• Nuclei and electrons are moving
around separately from each other
• Can be found in stars, lightning,
fluorescent lights, etc.
Pure Substances
Elements
• All atoms that make up an element are
the same
• They exhibit unique chemical & physical
properties
• They cannot be broken down into simpler
substances
• All known elements are found on the
periodic table
Compounds
• Can contain two or more different
elements in a fixed proportion
• Exhibit unique chemical & physical
properties
• Identified with chemical formulas
– Ex.
• H2O (water)
• CO2 (carbon dioxide)
Mixtures
• Made up of a combination of
elements and/or compounds
Solutions/Homogeneous Mixtures
• the chemical & physical properties of
the substance are the same
throughout
– Ex. Salt water, milk, soft drinks
Heterogeneous Mixtures
• Part of the substance exhibits
different chemical & physical
properties than other parts
– Ex.
• Chocolate chip cookies
• Oil and water
Properties of Matter
•
•
Distinguishing features that let us
identify what we’re examining
All matter has 2 different kinds of
distinguishing features:
1. Physical properties
2. Chemical properties
Physical Properties
• Can be observed without altering
chemical make-up of the substance
• Original substance can be retrieved
– Ex.
•
•
•
•
•
•
Hardness
Boiling point
Color
Odor
Melting point
Solubility
Chemical Properties
• Can be observed when a substance
reacts with another substance
• Original substance will be ‘lost’
• Done by conducting chemical tests
– Ex.
• Flame test – used to determine type of metal
• Lime water test – used to test for CO2
“Kinds” of Matter
matter
pure
substance
compounds
mixtures
elements
solutions
heterogeneous
mixtures