16-1 FUNDAMENTALS OF MATTER
Explain what a scientific model is
Identify individuals who contributed to the advancement of chemistry
FUNDAMENTALS OF MATTER
Scientist use models, but not always physical objects:
instead they are explanations that improve scientists’ understanding of
what is being studied.
Scientists have used many models in studying matter
Matter is anything that has mass and takes up space.
Aristotle, a Greek teacher who lived more than 2000 years ago, was one
of the first to study matter.
Aristotle’s model of matter was that everything was made from
four elements: earth, air, fire, and water.
wood was thought to be earth and fire.
steam was thought to be a combination of water and fire
believed everything was made up of tiny unbreakable spheres.
these spheres could not be made any smaller than they already were
named these little units “atoms” because the Greek work atomos meant
“cannot be divided”
believed that an atom could connect with other atoms to form al kinds
proved that matter was made of atoms and they did connect to form different types
J. J. Thompson
discovered that atoms contained small particles with a negative charge
he called them corpuscles and he believed that they floated randomly inside the
today we call them electrons
created a new model for explaining the structure of the atom
atom not solid, but mostly empty space
only the center was solid and he called it the nucleus
Later scientists discovered positively charged particles in the center of the atom, these
are called protons.
DID YOU KNOW?
If all the space were taken out of the atoms that make up your body, and the
electrons, protons, and neutrons were forced together, the total volume
of your body would be less than that of a grain of sand!!!
An atom is so empty that if it were the size of the Earth (13000km) its
nucleus would be less than 2 km across.
MORE LATER SCIENTISTS
In 1913, Neils Bohr proposed that the negatively charged electrons circle
the nucleus in established orbits like planets revolve around the sun.
This planetary model worked for some atoms but not for all.
discovered another type of particle in the nucleus next to the protons.
these particles lacked any electrical charge and were neutrons.
scientists believe that the atom is best explained by the electron-cloud
16-2: STATES OF MATTER
compare and contrast the states of matter
describe how the kinetic-molecular theory relates to changes of matter
STATES OF MATTER
Solids: keep the same shape and volume and when heated they change
Liquids: always keep the same volume but change shape depending on the
container they are in.
Gas: has no fixed shape or volume. It retains the shape and volume of its
Plasma: consists of matter that has lost electrons. It usually exists at
extremely high temperatures such as those found on the sun.
Kinetic refers to the energy of motion.
Kinetic-molecular theory deals with the motion of atoms.
according to this theory, all atoms have energy: hence, all atoms move.
atoms of solids have less kinetic energy than atoms of liquids and
gases, making them move more slowly.
the slower movement allows these atoms to hold tightly to surrounding
in liquid state atoms have more energy, they move faster and bounce
farther off each other
in gaseous form, atoms have the highest energy and move the fastest
and farthest apart.
At times, matter can change from a solid to a gas, or a gas to a
solid, without becoming a liquid in a process called sublimation.
Iodine crystals are heated, the atoms gain energy and move far apart and
become a gas.
Dry Ice is another example.
16-3: PROPERTIES OF MATTER
P H Y S I C A L
P R O P E R T I E S
Silver’s bright shiny luster
Water boils at 100 C
Chalk comes in many colors
Lipstick is made in many shades
Hard candies are sweet
Aluminum can be hammered into
thin sheets to form foil
C H E M I C A L
P R O P E R T I E S
Statues of marble and bronze
corroded by acids
Hardness of diamonds
Drain cleaner dissolves
Starter fluid helps charcoal
Silver compound in
photographic film breaks
down in light to form
Physical properties can be observed by the senses
Describes how different types of matter combine or interact with each other
to form new substances.
Reaction with oxygen: if paper becomes warm enough, it will combine with
oxygen in the air and burn
Reaction with acid: iron will react with the oxygen in water to form rust.
If baking soda combines with vinegar (an acid) bubbles of carbon dioxide
gas are produced. If baking soda combines with water instead of
vinegar, no bubbles are produced.
16-4: CHANGES OF MATTER
Distinguish between physical and chemical changes.
CHANGES OF MATTER
Matter has both physical and chemical properties and can go through
physical and chemical changes.
changes in which the properties of matter change but the identity of the
matter does not.
melting a metal
All of these physical changes make matter look different, but they don’t
change what it is.
Chemical changes are those in which one type of matter is changes into
another type of matter having different properties.
While absolute proof of a chemical change is provided only by chemical
analysis, certain easily observed changes provide strong evidence that
chemical changes have occurred.
production of heat or light
production of a gas
production of a precipitate, a solid substance that separates from