What is “matter”?
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The study of matter
“Matter” is anything that has mass and takes up space.
The mass of an object measures how much matter it
contains.*
The volume of an object is a measure of how much space it
occupies.
*Mass is not the exact same thing as weight, but they are very similar concepts. If
gravity changes, then weight will change, but mass will not.
Properties of matter
Extensive property: Depends on the amount of matter in a
sample. Any property that changes when you have more or less
of something.
e.g. Mass, volume
Intensive property: Depends on the type of matter in a sample,
but not the amount.
e.g. Color, boiling point
Solids
A solid has a fixed shape and volume. It is made of particles
that don’t flow freely. That means it will not change shape based
on the shape of its container, and it is not easily compressed
(can’t be squeezed into a smaller volume).
Porous solids like sponges or foam seem “compressible,” but
really they are just full of small holes/air pockets. When you
squish a sponge, you aren’t truly compressing a solid, you’re
just forcing air (a gas) out of it.
Liquids
A liquid has a fixed volume, but not a fixed shape. Unlike a solid,
a liquid’s particles can flow freely, so it changes shape to settle
into the shape of its container (but will not expand upwards
against gravity like a gas will).
Similar to solids, liquids are not compressible. You can’t squeeze
a liquid to make it take up less space.
Gases
A gas does not have a fixed volume or a fixed shape. It changes
shape to fit its container, and can expand to fill any volume
regardless of gravity.
Solids and liquids are not compressible because their
particles are already close enough to touch. In a gas, there
is a lot of empty space between the particles, so they are
much easier to compress into a smaller volume.
Mixtures
A mixture is a physical blend of two or more components.
In a heterogeneous mixture, the components are not evenly
distributed. If you take a few random samples, they likely will
not be identical in composition.
e.g. salad, bag of garbage, gravel, the human body
In a homogeneous mixture, the components are evenly
distributed. A few random samples will likely have very similar
compositions.
e.g. lemonade, air, hand sanitizer, blood, steel
Elements & Compounds
An element is the simplest form of matter that has a unique set
of properties. It cannot be broken down chemically into simpler
substances.
If it’s on the periodic table, it’s an element.
A compound is a substance that contains two or more elements
chemically combined (bonded) in a fixed proportion.
If it has a fixed chemical formula, it’s a compound.
A.
a compound
B.
a mixture of two
elements
C.
a mixture of a
compound and an
element
D.
a compound
E.
an element
F.
an element
G.
a mixture of two
compounds
H.
an element
I.
a compound
Chemical & Physical Change
Physical change: Some properties of a material change, but its
composition (what element or compound it is) does not.
e.g. boiling, melting, freezing, breaking, crushing
Chemical change: The composition/identity of the material (its
chemical formula) changes.
e.g. burning (combustion), rusting, cooking, digestion