Matter & Change
Chapter 1
What is Chemistry?
• The study of the composition, structure &
properties of matter & the changes it
undergoes
Mass vs. Matter
• Mass: the measure of the amount of
matter in something
• Matter: anything that has mass and
takes up space.
Atom vs. Element
• Atom: the smallest unit of an element that
maintains the properties of that element.
• Element: pure substance made only of one kind of
atom (found on the periodic table)
• You only need 1 atom to call matter an element
What is a Compound?
• Compound: is a substance that is made from the
atoms of two or more elements that are chemically
bonded.
• Ex: H2O, glucose (C6H12O6), NaCl
Classification of Matter
Pure Substances vs.
Mixtures
• All pure substances are either elements or
compounds!!
• ***If you can write the chemical formula for a
substance it is a pure substance
• Ex: H2O, Ag (silver), CO2, Pb (lead)
What is a Mixture?
• Mixture: made up of two or more kinds of matter
that retains its own properties and identity.
• You cannot write a chemical formula for a mixture
• Ex. Oil/water, pop, ketchup, air.
Two Types of Mixtures
• Homogeneous: same proportion of components
• It looks uniform/same throughout
• Ex. Salt water, milk (not spoiled!)
• Heterogeneous: does not have the same proportion of
components
• Can see more than one substance
• Ex. oil and water, granola bars
Properties of all Matter
Extensive vs. Intensive
• Extensive Property:
• DEPENDS on the amount of matter that is
present & will change if amount of matter changes
• Examples: volume, mass and energy
- A pencil is 15 cm in length
- The chemical reaction gave off 165 kilojoules of
energy
• Intensive Property:
• DOES NOT depend on the amount of matter
present and will not change if the amount of
matter is changed
• Examples: Color, Boiling/Freezing/Melting Points
and Density
- The color of the clown shoes are red
- The density of water is 1 g/cm3 & its bp is 100°C
Quantitative vs.
Qualitative
Measurements
• Quantitative – a description of a relevant
characteristic that involves a numerical
measurement
• Ex: The bird has a wingspan of 2 meters
• Qualitative – a description of a relevant
characteristic that does not involve a
numerical measurement
• Ex: The bird has a long wingspan
States of Matter
• Solid: has definite size and shape.
• Liquid: definite size, not a definite shape (takes the shape
of the container it’s in).
• Gas: no definite size or shape (fills the container it is in).
• Plasma: no definite size or shape (very energetic, constant
electron movement, looks like runny jello, its gooey).
Plasma is very rare.
Law of Conservation of
Mass
• Mass is neither created or destroyed in
chemical reactions
• The mass of a system may change state
(liquid to gas) but is never lost in ordinary
chemical reactions
• For this law to be tested properly a closed
system must be used
Physical Properties
• Physical Properties: are a characteristic
feature of a sample that can be observed or
measured without changing the identity of
the substance
• Examples: Melting/freezing/boiling points,
conductivity, malleability, density, color,
hardness, texture, taste, smell, viscosity
Chemical Properties
• Chemical Properties: are a characteristic
feature that relates to a substance’s ability to
undergo changes that transform it into
another/different chemical
• To identify this type of property, a chemical
change must be performed
• Examples: Reactivity, Flammability, new
color, new smell
Chemical Change
• A Chemical Change is a change in which one
or more substances are converted into
different substances
• A log burning or iron rusting
• MAKING COOKIES
Indicators of a Chemical
Change
• Color change
• Precipitation formed (ppt.): when 2
transparent liquids mix and a solid is formed
• Gas production (fizzing, bubbling)
• Odor change
• Explosion, flame or light production
• Thermal change when no outside energy is
added or subtracted from the system
Physical Change
• A physical change is a change in the
substance that DOES NOT involve a change
in the identity of the substance
• Examples: Cutting Hair or melting snow (all
changes of state are physical changes)
Phase changes are considered physical changes.
(No new substances are being formed.)
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Melting = solid to a liquid
Freezing = liquid to a solid
Boiling = liquid to a gas
Condensation = gas to a liquid
Evaporation = liquid to a gas
Sublimation = solid to a liquid
Property vs. Change
Examples
• The pencil is 15 cm in length (property)
• The pencil is cut in half and each piece is now
7.5 cm in length (change)
• The color of phenolphthalein is clear
(property)
• The color of phenolphthalein changed from
clear to magenta when placed in ammonia
(change)