AW Ch 2 Matter and Change

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AW Ch 2 Matter and Change

• 2.1 Matter
• Properties of Matter
• Matter Anything that has mass and takes up
  space.
• Mass The amount of matter that an object
  contains.
• Substance - Matter that has a uniform and
  definite composition.
• - Contain only one kind of
  matter.
• - Pure substance is another
  term for substance.
• - All substance samples have
  identical physical properties.
• A substance Table sugar, composed of 100
  sucrose.
• A non-substance Lemonade, varying amounts
  of lemon juice,
• water, and sugar.

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AW Ch 2 Matter and Change
Types of Physical Properties State Color
Melting Point and Boiling Point
Density solid, has color, oC (degrees
Celsius) g/cm3
liquid, or is g/mL or gas
colorless g/L Properties of the States
of Matter
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AW Ch 2 Matter and Change
Table 2.1 Physical Properties of Some Common
Substances
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AW Ch 2 Matter and Change

• Description of the States of Matter
• Physical Change
• A change which alters a material without
  changing its composition or
• identity.
• A physical change occurs as a substance changes
  from one state to
• another.
• Examples Cutting, grinding, bending, melting,
  boiling, freezing a material.
• Note
• The process of melting ice to liquid water, then
  heating the water to its
• boiling point to steam results in physical
  changes of state in the water.
• The waters molecular composition, however,
  remains unchanged,
• despite the changes in state.
• Water molecules are identical, regardless of
  physical state, as the water
• changes state from ice to liquid water and
  then to steam.

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AW Ch 2 Matter and Change
States of Matter Solid Form of matter with
definite shape and volume. Liquid Matter that
flows, has fixed volume, takes shape of its
container. Gas Form of matter that that takes
shape and volume of its container easily
compressed. Vapor Gaseous state of a substance
that is generally a liquid or solid at room
temperature, e.g., steam is the gaseous state of
water, which is a liquid at room temperature.
Moist air contains water vapor. Plasma A
high-temperature physical state of matter in
which atoms lose their electrons.
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AW Ch 2 Matter and Change
Properties of the States of Matter Extensive
properties of matter Depend on the amount of
matter that is present. These include volume,
mass, and the amount of energy in a
substance Intensive properties of matter Do not
depend on the amount of matter present. These
include melting point, boiling point, density,
and ability to conduct electricity and heat.
Intensive properties remain the same regardless
of how much of the substance is present. A
physical property of matter Observable or
measurable quality or condition of a substance
that does not change the substances chemical
composition. Examples Melting point and boiling
point.
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AW Ch 2 Matter and Change

• 2.2 Mixtures
• Mixtures
• Classifying Mixtures
• Mixture A physical blend of two or more
  substances.
• Compositions may vary.
• Examples
• Salad made of tomato, celery, and lettuce.
• Forest containing different types of tree.
• Blood is a mixture of water, chemicals, and
  cells. Composition in your
• body varies with time of day. Blood
  composition also varies from
• one person to another.
• Bucket filled with mud, sand, gravel and water.
  

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AW Ch 2 Matter and Change
2.2 Mixtures Mixtures Two Types of Mixtures
Heterogeneous Mixture - Not uniform in
composition, e.g., fruit salad. Homogeneous
Mixture - Completely uniform composition, e.g.,
salt water (components evenly distributed
throughout the sample.) Solution - Another term
for a homogeneous mixture.
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AW Ch 2 Matter and Change

• 2.2 Mixtures
• Separating Mixtures
• Some mixtures can be separated into their
  components by simple physical methods.
• Examples
• Using fork to separate taco filling mixture into
  meat, lettuce, and cheese.
• Using magnet to separate a mixture of sand and
  iron filings.
• Distillation Method of separating a homogeneous
  mixture of water and substances dissolved in it.
• The liquid water is boiled to produce a vapor
  and then condensed to a liquid.
• Solid substances dissolved in the water remain
  in the distillation flask because they do not
  change to a vapor. (See AW Fig 2.5, p. 34.)

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AW Ch 2 Matter and Change

• 2.3 Elements and Compounds
• Distinguishing Elements and Compounds
• Substances Classified in two groups elements
  and compounds.
• Elements
• Simplest forms of matter that can exist under
  normal lab conditions.
• Cannot be separated into simpler substances
  under normal lab conditions.
• Building blocks for all other substances.
• Examples of elements oxygen, hydrogen, and
  carbon
• Atom Smallest unit of an element that maintains
  the properties of that element. Both elements and
  compounds are made of atoms.

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AW Ch 2 Matter and Change

• 2.3 Elements and Compounds
• Distinguishing Elements and Compounds
• Compounds
• Substances that can be separated into simpler
  substances only by
• chemical means.
• Formed by the chemical combination of two or
  more elements.
• Example of Breaking Down a Compound into its
  Elements through Chemical Change.
• Table sugar heated in a skillet turns black as
  it undergoes a chemical
• change to break down into carbon, an
  element, and water vapor, a
• molecular compound.
• Water molecules can undergo change into the
  elements of hydrogen and
• oxygen in the presence of electricity.

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AW Ch 2 Matter and Change
Fig 2.7 Chemical Decomposition of a Compound into
its Elements
Chemical change
Carbon Element
Water Compound
Sugar Compound
Heat
Chemical change
Hydrogen Element
Oxygen Element
Water Compound
Electricity
Compound Elements of the Compound Sugar Carbon,
hydrogen, oxygen
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AW Ch 2 Matter and Change
2.3 Elements and Compounds Fig. 2.8
Distinguishing Elements, Compounds, and Mixtures
Matter
Physically separable?
No
Yes
Pure Substance (or Substance for short) Definite
composition homogeneous
Mixture (of Substances) Variable composition
Chemically separable?
Uniform composition?
Yes
No
No
Yes
Homogeneous mixture (solution) Uniform texture
(air, tap water, gold alloy)
Heterogeneous mixture Non-uniform distinct
phases (soup, concrete, granite)
Compound (water, iron sulfide, sodium chloride,
sugar)
Element (iron sulfur, carbon, hydrogen, iron)
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AW Ch 2 Matter and Change

• 2.3 Elements and Compounds
• Symbols and Formulas
• Every compound is represented by a one- or
  two-letter symbol.
• First letter always capitalized, second letter
  is lower case.
• Examples hydrogen, H
• oxygen, O
• neon, Ne
• chlorine, Cl
• Purpose Provides a shorthand way to write the
  chemical formulas of
• compounds.
• A specific compound is always made up of the
  same elements in the
• same proportions, so the formula specific
  compound is always the same.

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Symbols and Name Origins for Some Elements
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AW Ch 2 Matter and Change
2.4 Chemical Reactions Changing Reactants to
Products Chemical reaction Chemical process by
which one or more substances change into new
substances. Examples - iron chemically
combining with oxygen to form rust
- antacid tablet dropped into a glass of
water - fireworks exploding
- tree leaves changing color in
the fall Reactants The starting substances in a
chemical reaction. Products The substances
formed in a chemical reaction. Reaction arrow
Stands for change into or produce
Reactants
Product
heat
iron sulfur
Iron sulfide
Translation Heating the reactants iron and
sulfur produces iron sulfide as a product.
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AW Ch 2 Matter and Change
2.4 Chemical Reactions Changing Reactants to
Products Chemical change indicators 1. Energy
absorbed or given off - cooking a raw
steak, absorbs heat - burning natural gas
on a stove, releases heat Note Energy also
absorbed or released when a substance changes its
physical state (ice melts to water by absorbing
heat, steam condenses to water by releasing
heat). So an energy change is not necessarily
proof that a chemical change has occurred. 2.
Formation of a gas (can also indicate physical
change - water to steam) 3. Color change (dried
paint on a wall fading in sunlight) 4.
Irreversible change (rust cant easily change
back into iron and oxygen)
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AW Ch 2 Matter and Change
Conservation of Mass Combustion (burning) is a
type of chemical reaction. Coal burned with
oxygen in air produces carbon dioxide gas, water
vapor, and ash residue. The change seems to
involve a reduction in the amount of matter,
e.g., lump of coal reduced to ash. But
measurement shows that the total mass of the
reactants (coal and oxygen) equals the total mass
of the products (carbon dioxide, water vapor, and
ash) when the gases involved are accounted for.
During any chemical or physical change 1.
Quantity of matter is unchanged during the
reaction. 2. Mass of products is always equal
to mass of reactants. Law of Conservation of Mass
- In any physical change or chemical reaction,
matter is neither created nor destroyed it is
conserved. Example When a light bulb burns out,
the magnesium wire filament burns in oxygen gas
to produce magnesium oxide. The mass of the light
bulb, including the gas captured inside, remains
the same after the bulb burns out.
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Holt 1-3 Elements
Introduction to the Periodic Table Groups (or
families) Vertical columns on the periodic
table. Periods Horizontal rows on the periodic
table Types of elements - Metal An element
that is a good conductor of heat and electricity.
- Nonmetal Many of these elements are gases at
room temperature. Tend to be brittle, rather than
malleable (pound flat) and ductile (draw into a
wire). Some nonmetals Solid Nonmetals Liquid
nonmetals Gas nonmetals carbon,
C bromine, Br nitrogen, N phosphorus, P
oxygen, O selenium, Se
fluorine, F sulfur, S chlorine, Cl iodine,
I
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Holt 1-3 Elements

• Introduction to the Periodic Table
• Metalloid
• An element that has some characteristics of
  metals and some
• characteristics of nonmetals.
• All metalloids are solids at room temperature
• Less malleable than metals, but not as brittle
  as nonmetals
• Tend to be semiconductors of electricity
  (silicon, Si)
• Noble gases - Elements in Group 18 of the
  periodic table.
• Generally unreactive.
• Examples neon, Ne, argon, Ar, krypton, Kr,
  xenon, Xe, and helium, He

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Student Study Guide
Key Terms chemical property homogeneous
mixture physical change chemical reaction law
of conservation of mass physical
property chemical symbol liquid product compou
nd mass reactant distillation matter solut
ion element mixture substance heterogeneous
mixture phase vapor
Key Relationship Law of conservation of mass
mass of reactants mass of products
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• Concept Summary
• 2.1 Matter
• Matter has mass and occupies space.
• Three common states of matter are solid, liquid,
  and gas.
• A pure substance contains one kind of matter
• 2.2. Mixtures
• A mixture is a physical combination of two or
  more substances that can be separated by physical
  means.
• Heterogeneous mixtures are not uniform in
  composition.
• Homogeneous mixtures, also called solutions, have
  uniform properties throughout and may be gases,
  liquids, or solids.

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• Concept Summary
• 2.3 Elements and Compounds.
• Elements are the simplest forms of matter that
  exist under normal conditions.
• Elements are always present in the same ratio in
  a given compound.
• Properties of a compound are usually different
  from those of the elements composing it.
• Chemical methods are required to separate
  compounds into their constituent elements.
• Each element is represented by a one- or
  two-letter chemical symbol. Chemical symbols of
  the elements are used as a shorthand method of
  writing chemical formulas of compounds.
• 2.4 Chemical Reactions
• A physical change in the physical properties of a
  substance without a change in chemical
  composition.
• A chemical change is a change in the chemical
  composition of a substance.
• In a chemical change (chemical reaction),
  reactants are converted to products. Mass is
  conserved in any physical or chemical change.