Download What is Chemistry

Properties and
Changes of Matter
Unit One
Chapter 2
Properties of Matter
• What is Matter?
– Anything that has mass and takes up space
• What is mass?
– Amount of matter an object contains
Types of Matter
• Substance
– Matter that has definite and uniform composition
• Mixture
– Physical blend of two or more substances that
can be separated using physical means.
• Filtration
• Distillation
Types of Matter
One type of “stuff”
More than one
type of “stuff”
together
Types of Substances
• Elements
– Simplest form of matter
• Compounds
– composed of more than one type of atom
– Can be separated into simpler substances by
chemical means
Types of Mixtures
• Heterogeneous
– Multiple phases
• Homogeneous
– All in a single phase
Homogeneous Mixtures are Solutions
• Solvent
– The substances that does the dissolving
– Present in the greater amount
• Solute
– The substances that gets dissolved
– Present in the smaller amount
Heterogenous or Homogeneous
•
•
•
•
•
•
Saltwater
Spaghetti sauce
Muddy water
Cough syrup
Salad
Brass
Physical Properties of Matter
– Quality of a subtance that can be observed or measured without
changing the substance
• Melting/boiling point, color, density. Mass
Types of Physical Properties
• Two types of Physical Properties
– Intensive
• Are constant regardless of the amount of the
substance
– Melt. Pt/Boil. Pt
– Density
– Extensive
• Vary depending on amount of substance present
– Mass
– Volume
• Intensive properties are inherent to a substance and
can aid in identifying an unknown sample
Phases of Matter
soli
d
• 3 common phases
–Solid
•Definite shape
•Definite volume
•Highly rigid and organized – particles vibrate around fixed points
•Nearly incompressible, does not flow
–Liquid
•Definite volume
•Indefinite shape
•Fluid – takes the
shape of its container,
slightly compressible
–Gas
•Indefinte shape –
•Indefinite volume
•Very fluid - takes shape and
volume of containter
•Particles move randomly with high
energy, very compressible
Additional Phases of Matter
• Bose-Einsten Condensate
– Exists as temperatures approach absolute
zero (-273 °C)
– Extremely dense, but less structured than
solid
• Plasma
– Energy similar to gas
– Contains ions rather than atoms
• Attraction of ionic charges pull molecules
closer together than in gas
Definitions related to changes in Matter
• Vapor
– Gaseous state of a substance that is in the
liquid or solid state at normal temperatture
• Temperature
– Average kinetic energy of the particles
(atoms, molecules, etc.) of the substance
Physical Changes to Matter
• Changes that do not alter the
chemical compostion
• Change in size or shape
• Change in phase
Chemical Properties of Matter
• Ability of a substance to react and
form a new substance
–Can only be observed or
measured by changing the
substance into a different
substance
Chemical Changes to Matter
• Results in the formation of a new substances
– A chemical reaction takes place
• Evidence that a chemical reaction has taken place
– Change in energy
• Temperature increase or decrease
– Production of a gas
• Formation of bubbles or detection of odor
– Formation of a precipitate
• Presence of a solid
– Color change
Chemical Reactions
• One or more substances change
into a new substance
–Reactants
• The substances that exist before the
reaction/chemical change takes place
–Products
• The substances that form as a result of
the reaction/chemical change
Evidence of a Chemical
Reaction
•
•
•
•
Formation of a gas
Formation of a solid (precipitate)
Color change
Change in energy (absorbed or given
off)
Practice: classify the following as
physical or chemical properties of water
1. Colorless
2. Changes from a liquid to a gas at 100ºC
3. Decomposed by electricity into hydrogen and
oxygen
4. Freezes at 0 ºC
5. Produces acetylene gas when dropped in calcium
carbide
6. Produces a gas when reacted with sodium
Practice: Classify the following as
physical or chemical changes:
1. Bending a piece of wire into a new shape
2. Cooking a steak
3. Cutting the grass
4. Souring of milk
5. Burning coal
6. Dissolving sugar in water
7. Growing grass
8. Stretching a rubber band
Law of Conservation of Mass
• The amount of matter present before the reaction
takes place will equal the amount of matter at the
completion of the reaction
Food for Thought:
If 4.0 g of hydrogen are
combined with a mass of
oxygen to make 36.0 g of
water, how many grams of
oxygen were used in the
reaction?