Chapter (2) Notes (Matter)
Matter- Anything that has mass and takes up
space.
There are 3 states of matter: solids, liquids,
and gasses.
Chemistry- The study of the properties of matter
and how matter changes.
The properties and changes of any type of
matter depend on its makeup. Some types of
matter are substances and some are not.
Substance- Is a single kind of matter that is
pure, meaning it always has a specific makeup,
or composition, and a specific set of properties.
Substances can be described as solids, liquids,
or gasses.
Examples of pure substances: include tin,
sulfur, diamond, water, pure sugar
(sucrose), table salt (sodium chloride) and
baking soda (sodium bicarbonate). Crystals, in
general, are pure substances. Tin, sulfur, and
diamond are examples of pure substances that
are chemical elements. All elements are pure
substances. Pure substances are only made
up of one kind of matter.
Flour, baking powder, milk, eggs, and fruit are
not pure substances.
Every form of matter has 2 kinds of properties:
Physical Properties and Chemical Properties.
Example: A physical property of oxygen is that
it is a gas at room temperature. A chemical
property is that it reacts with iron to form rust.
Physical property- Is a characteristic of a pure
substance that can be observed without
changing it into another substance. The
properties can be observed by looking or
touching a substance. Example: When water
freezes and changes to ice.
Chemical property- Is a characteristic of a pure
substance that describes its ability to change
into different substances. Example: When iron
combines slowly with oxygen in the air to form a
different substance, rust. Another example is
when silver reacts with sulfur in the air to form
tarnish. Other examples are when yeast is
added to dough and it produces gases, (spaces
in bread) and causes the bread to rise.
Compound- Is a pure substance made of two or
more elements chemically combined in a set
ratio. A compound may be represented by a
chemical formula, which shows the elements in
the compound and the ratio of atoms.
Example: CO (carbon monoxide has the ratio
of carbon atoms to oxygen atoms is 1 to 1.
When elements are chemically combined, they
form compounds having properties that are
different from those of the uncombined
elements. For example, the element is sulfur is
a yellow solid, and the element silver is a shiny
metal. But, when silver and sulfur combine,
they form a compound called silver sulfide,
Ag2S. This is a black compound that we call
tarnish.
Mixtures- Made of two or more substances
(elements, compounds, or both) that are
together in the same place but are not
chemically combined
3 Ways that mixtures differ from compounds
1.
Each substance in a mixture keeps its
individual properties
2. The parts of a mixture are not combined in
a set ratio
3. A compound can be difficult to separate
into its elements, but a mixture is usually
easy to separate into its components
because each component keeps its own
properties
There are 2 types of mixtures: Heterogeneous
Mixtures and Homogeneous Mixtures.
Heterogeneous Mixture- you can see the
different parts. (Examples: salad, soil)
Homogeneous Mixture- The substances are so
evenly mixed that you can not see the different
parts. (Example: Stirring sugar into water
when it dissolves, Air, and solutions)
Ways to Measure Matter
1. Measuring weight
2. Measuring mass (Triple beam balance)
3. Finding Volume (L x W x H)
4. Calculating the Density (D = M/V
Changes in Matter
Physical Change- Is any change that alters the
form or appearance of matter but does not
make any substance in the matter into a
different substance. A substance that
undergoes a physical change is still the same
substance after the change (Example: sand
artist, melting of an ice cube, bending, crushing,
breaking, chopping and anything else that
changes only the shape or form of matter). A
change in state, such as from a solid to a liquid
or from a liquid to a gas is an example of a
physical change.
Chemical Change (chemical reaction)- Is a
change in matter that produces one or more
new substances. When a substance is
transformed into a different substance. Unlike a
physical change, a chemical change produces
new substances with properties different from
those of the original substances. (e.g.
Photosynthesis-plants convert electromagnetic
energy from the sun into chemical energy).
Reduction- How iron is made from iron
ore.
The Law of Conservation of Mass (Matter)Matter is not created or destroyed in any
chemical or physical change.
*Mass measures the amount of Matter.
According to the law of conservation of mass,
the mass of all substances that are present
before a chemical change, known as the
reactants, equals the mass of all of the
substances that remain after the change, which
are called the products.
The Law of Conservation of Mass
total mass of the reactants = total mass of the
products
Remember, that no mass is lost, because
during a chemical change, atoms are not lost or
gained, only rearranged.
●
In the reaction, the bonds in the methane and oxygen come
apart, the atoms rearrange and then re-bond to form water and
carbon dioxide.
●
The little number written at the lower right after an atom
(subscript) tells how many of that atom are in the molecule.
●
The big number written in front of a molecule (coefficient)
shows how many of that molecule there are.
●
All the atoms in the products come from the atoms in the
reactants.
Matter and Thermal Energy
Energy- Is the ability to do work or cause
change.
Every chemical or physical change in matter
includes a change in energy. (Example:
bending a paper clip, ice changing to liquid,
candle burning give off energy)
Temperature- Is the measure of the average
energy of random motion of particles of matter.
Particles of gas in the warm outside air have
greater average energy of motion than particles
of air in a cool building.
Temperature is related to the amount of thermal
energy an object has.
Thermal Energy- Is the total energy of all
particles in an object (e.g. Air in a room as cold
or hot)
Thermal energy always flows from warmer
matter to cooler matter (e.g. thermal energy
from a hot cup of cocoa can warm cold hands).
When matter changes, the most common form
of energy released or absorbed is thermal
energy (e.g. ice absorbs thermal energy from its
surroundings when it melts, also the use of a
cooler)
Endothermic Change- A change in which
energy is taken in (e.g. melting of ice)
Exothermic change- A change in which energy
is released. (e.g. warming hands near a wood
fire).
Law of Conservation of Energy
Energy- Ability to do work
The Law states that energy cannot be created
or destroyed in chemical reactions. It can only
be transformed (changed from one form to
another).
5 Forms of Energy
1.
2.
3.
4.
5.
Kinetic energy- Is energy of matter in
motion (e.g. rolling bowling ball, electrons
moving around in the energy levels).
Potential energy- Is the energy an object
has because of its position. It is stored
energy (e.g. energy stored in a bike at the
top of a hill, a stretched rubber band).
Chemical energy- Internal energy that is
stored in chemical bonds between atoms.
Electromagnetic energy- A form of energy
that travels through space as waves (e.g.
radio waves, infrared rays, waves that
heat food in microwaves, ultraviolet rays
and x-rays).
Electrical energy- Is the energy of
electrically charged particles moving from
one place to another (e.g. in the nucleus
of an atom, electrolysis).