вход по аккаунту

код для вставкиСкачать
SOL 6.4
Matter= anything that has mass and takes up
Examples: fruit, softballs, tools, animals, rain,
flowers and even air.
Mass=how much of something you have.
Energy is the ability to do work or cause
Change can mean…
1. motion=moving matter from one place
to another. (ex. nail being hammered into
2. change in form (ex. water boiling or
The study of the properties of matter and how
matter changes is called chemistry.
Matter has a variety of characteristics or
properties that can differ.
They fall into 2 different groups used to
identify, describe and classify matter:
A single kind of matter that has distinct
physical and chemical properties is called a
A physical property can be observed without
changing the substance into something
 Odor
 Taste
 Hardness
 Texture
 Color
 Temperature at which a solid melts or liquid
 Whether its solid, liquid or gas
A chemical property is observed when a
substance interacts with another substance.
 Burning or flammability
 Rusting
 Tarnishing
 Whether an object will explode
What is an example of a physical property of
a candle? Chemical property?
An element is a substance that
cannot be broken down into
any other substances by
chemical or physical means.
All elements can be identified
by its specific physical and
chemical properties.
Examples: aluminum foil,
copper coatings on pennies,
oxygen and nitrogen gas.
All of the kinds of elements are found on the
periodic table along with their symbols.
A compound is a substance made of two or
more elements chemically combined in a set
ratio or proportion.
Examples: Carbon Dioxide gas is a compound
made up of Carbon and Oxygen. Water is a
compound made up of oxygen and hydrogen.
When elements are combined to make a
compound, the new substance has properties
different from those of the original elements.
Example: table sugar is made up of 3
elements- Carbon, Oxygen and Hydrogen.
Carbon=found in charcoal
Oxygen/hydrogen=colorless gases
Do sugar crystals resemble them?
Most matter occurs in mixtures.
A mixture is made from two or more
substances (elements or compounds) that are
in the same place but are NOT chemically
Mixtures differ from compounds in 2 ways:
The substances in a mixture keep their
individual properties.
The parts of a mixture are not necessarily
present in set ratios.
Example: soil has particles of sand, tiny bits of
clay, and pieces of decaying plants.
If you were to grab 2 handfuls of soil would they
be made up of the same amount of clay,
sand, and decaying plant matter?
Which is a mixture and which is a compound?
 Chex mix
 Table salt
 Water
 Muddy water
 Carbon dioxide
There are 2 types of changes that matter goes
through: physical and chemical.
Physical change= a change that alters the form
or appearance of a material but does NOT
make the material into another substance.
Examples: chopping wood, bending a copper
wire, molding clay.
Matter has 3 principal states: solid, liquid and
gas. A change in state is an example of a
physical change.
Why is a change in state considered to be a
physical change?
A chemical change or reaction is a change in
matter that produces new substances with
properties different from the original
Elements may combine to form a compound or
compounds may be broken down into
Examples: souring of milk, burning of wood
Energy is ALWAYS involved when a chemical or
physical change to matter occurs.
Think of tearing a sheet of aluminum foil in
half and then tearing the halves into quarters
and so on…
Could you keep tearing forever producing
smaller and smaller pieces or would you
eventually reach the smallest possible piece?
Democritus, a greek philosopher who lived in
440 B.C., thought that you could cut matter
into smaller and smaller pieces until you
eventually got to its smallest piece.
He called this smallest piece atomos meaning
Look familiar?
This is where the word atom comes from
which is the smallest particle of an element.
In 1802, John Dalton (a British school teacher)
proposed an atomic theory.
His main conclusions were:
Atoms can’t be broken into smaller pieces.
In any element, all of the atoms are
exactly alike.
Atoms of different elements are different.
Atoms of two or more elements can
combine to form compounds.
Atoms of each compound have a unique
The masses of the elements in a
compound are always in a constant ratio.
Today, scientists have identified some
important exceptions to Dalton’s statements
but his ideas still form the basis of our
understanding of atoms.
What were two of Dalton’s ideas about atoms?
Although atoms are extremely small, they are
made of even smaller parts: nucleus,
protons, neutrons and electrons.
Nucleus= the tiny, central core of the atom,
which contains protons and neutrons.
Protons=have a positive electric charge (+).
Neutrons=have no charge. (they are neutral)
Electrons= very energetic particles that move
in the space around the nucleus and carry a
negative charge (-).
All atoms of a particular element have the
same number of protons. Because the
number of protons is unique to each element,
this number is called the element’s atomic
Example: the atoms that make up the element
carbon all have 6 protons so the atomic
number for carbon is 6.
The force that hold two atoms together is a
chemical bond.
Two or more atoms that are bonded together
form a molecule.
Some are made up of only one type of atom
but most are made up of two or more
different types of atoms bonded together.
Scientists can’t study atoms by looking at
them. (They are too small to see!)
So….How do they study them?
They make inferences about them based on
They use models to make and test their
How are atoms and molecules related?
Molecules= Two or more atoms chemically
Compounds= Two or more different elements
chemically combined
During the California gold rush, miners
needed a way to remove Gold from a
mixture that also contained dirt and sand.
Gold can be separated from other materials
in a mixture because of its density. (It has a
higher density than most other materials
including fool’s gold.)
They used the method of panning using a
shallow pan and water. Because gold is
more dense, it stays in the bottom of the
pan when the less dense materials (water,
dirt, sand) are poured off.
How could you tell the difference between
fools gold and real gold?
Пожаловаться на содержимое документа