Name______
Science
Grade_________________
September_____________
Grade 8 Chapter 2 Sect 1 voc and notes
matter
chemistry
substance
physical property
chemical property
element
atom
chemical bond
molecule
compound
chemical formula
mixture
heterogeneous mixture
homozygous mixture
solution
Anything that has mass and takes up space is called matter. The study of the
properties of matter and how matter changes is called chemistry. A substance is
a single type of matter that is pure, having a specific composition and set of
properties.
Every type of matter has 2 kinds of properties- chemical and physical. For
example; oxygen is a gas at room temperature(physical property). Oxygen
reacting with iron to form rust(chemical property).
Physical properties of matter are characteristics of pure substances that ca be
seen without changing it to another substance. Freezing liquid water to ice is
physical. It still is water, but the stage of the water has changed. The change of
state, hardness and texture are other kinds of physical properties.
When you have matter that changes into another substance after reacting with
another matter, that is a chemical change. yeast added to dough produces gas to
make bread, iron and oxygen react to make rust an silver and sulfur create
tarnish(pure silver that turns black).
Elements that are pure substances that cannot be broken down into any other
substance. They are the simplest substances. Aluminum, zinc, nitrogen, oxygen
are all elements. Elements are usually represented by a 1 or 2 letter symbol such
as N for nitrogen or Au for gold.
The basic particle that makes up all elements are called atoms. Different
elements have different properties because of their atoms being different.
Atoms are made up of even smaller parts, some of which are charged.
Most atoms have the ability to combine with other atoms. When this happens, it
is called a chemical bond. Atoms join to form larger particle called molecules.
Molecules are groups of 2 or more atoms held by chemical bonds A water
molecule is made up of hydrogen molecules and oxygen molecules.
When elements are chemically combined, they form compounds. These
compounds have different properties from those of the uncombined elements.
For example, sulfur is a solid yellow element. Silver is a shiny metal. But when
chemically combined to form silver sulfide, Silver sulfide is a n=black material,
commonly known as tarnish .
Compounds are usually shown as a chemical formula, For example, water is
represented as H2 O. Silver sulfide(tarnish) is shown as Ag2 S
A mixture is made of 2 or more substances that are held together, but not
chemically combined. Each substance in a mixture keeps its individual
properties and the parts of a mixture are not combined in a set ratio. For
example, a handful of moist soil might contain sand, clay bits of decaying plants
even insects. A handful of soil from a different place may not contain the same
items or the amount of sand, clay and decaying matter may differ.
There are 2 types of mixtures: heterogeneous and homogeneous. In
heterogeneous mixtures, you can see all of the different parts. For example, a
salad is a mixture that is heterogeneous because you are able to pick out the
lettuce, tomatoes, olives, cucumbers, etc.
A homogeneous mixture is a mixture where all the parts are so evenly mixed that
you cannot see the different parts. For example, when you stir sugar into water,
the sugar eventually dissolves. You no longer can see the sugar particles, but you
know they are in there. This is called a solution. Air( nitrogen, oxygen and other
gasses) is another example and so is brass(copper and zinc)
How can you separate parts of a this mixture? Iron filings, powdered sulfur and
table salt are mixed in together. How could you separate the iron filings? You
could use a _____________________________. What if you just wanted to
separate the sulfur powder? You can ______________________________ into
the remaining sulfur/salt mixture and then pour that into a
_________________________ that is on the top of a jar so only the sulfur
remains behind.
How can we now just get the salt? Just ________________the solution until only
the salt remains behins.