Matter – Properties and Changes
What is Matter?
Matter is anything that takes up space and has mass.
Mass is the amount of matter in an object.
Types of Matter
Matter
Pure Substance Mixtures
Elements Compounds Heterogeneous Homogeneous
Examples:
Properties
Words that describe matter (adjectives) Physical Property - a property that can
be observed and measured without changing the substance. Examples:
Chemical Property - a property that can only be observed by changing the type of substance. Examples:
Properties
Words that describe matter (adjectives) Extensive Property - depend on the
amount of matter Ex:
Intensive Property - only depend on the type of matter, not the amount Ex: Used to identify a substance
States of matter
Solid- matter that can not flow and has definite volume.
Liquid- definite volume but takes the shape of its container (flows).
Gas- a substance without definite volume or shape and can flow. Vapor- a substance that is currently a gas but
normally is a liquid or solid at room temperature.
States of MatterStates of Matter
Solid
Liquid
Gas
Definite Volume?
YES
YES
NO
Definite Shape?
YES
NO
NO
Expansion w/ Temp. increase
Small Expans.
Small Expans.
Large Expans.
Com-pressible?
NO
NO
YES
Solid Liquid Gas
Melt Boil
CondenseFreeze
Sublimation
Deposition
States of Matter
Plasma:
Occurs at high temperature low pressure
Formed when electrons separate from nucleus of gases
Most common state of matter in the universe
Changes in Matter
Physical Changes & Chemical Changes
These alter the appearance of matter without changing its composition. Examples?
Changes of the state (or phase) of matter is a physical change
The temperature & pressure at which matter changes phase are important physical properties These are melting & boiling points
Physical Changes
Another Way to Change States
Pressure For some substances it will turn solids to liquids
EX: Ice Skating
For others it will turn liquids to solids Ex: Silly Putty
Will turn gas to liquid Compressor in refrigerator and AC
Will turn gas to solid Formation of Dry Ice
Chemical Changes
Occur when one or more substances react and form a new substance
These are also called chemical reactions
Products of the chemical reactions ALWAYS have different properties than the original materials
Evidence of Chemical Reactions:
Formation of a gas Formation of a solid
precipitate Drastic color change Energy changes – temp. changes or
formation of light Exothermic vs. Endothermic Reactions
Change in the smell of a substance
Conservation of Mass
Mass can not be created or destroyed in ordinary chemical changes
All the mass can be accounted for Mass at the start = mass at end So the total mass of the products should
equal the total mass of the reactants
Antoine Lavoisier
Considered the father of modern Chemistry
Discovered the Law of Conservation of Mass (also called the Law of Conservation of Matter)
Did experiments on reactions.
Mixtures
A physical combination of two or more substances
Heterogeneous - you can see the individual substances that make it up. Ex: Chocolate chip cookie dough, gravel, soil.
Homogeneous- you cannot see the individual substances that make it up, it always has a single phase. Ex: Kool-aid, air.
Solutions
Another name for homogeneous mixture Can occur between any state of matter.
Examples: Liquid
Solid
Gas
Separating mixtures
Only physical changes - no new matter formed Filtration- separate solids from liquids with a barrier
Distillation- separate because of different boiling points Heat mixture Catch purified vapor in cooled area
Chromatography- different substances are attracted to paper or gel, so move at different speeds
Crystallization – pure solids form when solid particles come out of solution (make crystals)
Elements & Compounds
Section 3.4
Elements
Simplest pure substance Cannot be broken down into simpler matter by
normal physical or chemical means All one kind of atom Each one has a unique name and symbol. In
the symbol the first letter is always capitalized and the remaining letter(s) are lowercase.
There are 91 naturally occurring elements Who was given credit for organizing them into a
table? Dmitri Mendeleev
Compounds
Chemical combinations of two or more different elements
When they are broken down, the pieces have completely different properties than the compound. For example: Salt
Most of the substances we work with are compounds
Chemical Symbols
Used to write chemical formulas You know it is a formula because there will be
more than one capital letter Subscripts tell us how many of each atom in the
formula. H2O
C3H8
HBrO3
Laws of Compounds
By accounting for the mass of all matter there are a couple of laws that govern how compounds are created. Law of Definite Proportions
Law of Multiple Proportions
Law of Definite Proportions
Each compound has a specific ratio of elements by mass It is always a whole # ratio
For example – the chemical formula for water is always H2O
You can also see its ratio by mass: Water is always 8 grams of oxygen for each gram of
hydrogen
This does not change, no matter where you are on Earth! (Or in the universe for that matter)
Law of Def. Prop. Continued…
This law can be verified by determining the percent by mass of the elements in a compound:
Example: A compound contains 52.46 g of iron and 22.54 g of oxygen. What is the percent composition of oxygen?
30.05 % Oxygen
mass of elementPercent by mass (%) = 100
mass of compoundx
Law of Multiple Proportions
The textbook states that when the same elements combine to make different compounds, they combine in small whole number ratios.
You will NOT get fractions of elements Examples:
CuCl vs. CuCl2
CH4 vs. C2H6
Review
What makes a form of matter a substance? What are some examples?
How do you distinguish between chemical and physical properties?
What is the difference between a physical change and a chemical change? Give one example of each.
Why is a solution a homogeneous mixture? What is one way to separate a homogeneous mixture?
Explain how you would tell that NaCl is a compound but Na is an element.
Explain how all compounds obey the laws of definite and multiple proportions.