Matter

Chemistry
• The field of study concerned with the properties,
structure, composition, classification, and
transformations of matter.
Matter
• Anything that has mass and occupies space.
• Includes all things – both living and nonliving
Examples: plants, soil, air, bacteria
• Various forms of energy such as heat, light, and
electricity are not considered to be matter.
• The universe is composed entirely of matter and
energy.
States of Matter
• A substance may be either a solid, liquid, gas,
plasma, or bose-einstein condensate
• The state of matter observed for a particular
substance depends on its:
▫ Temperature
▫ Surrounding pressure
▫ Strength of the forces holding its structural
particles together
Solids
• Have a definite shape and volume
• Do not flow
• Have particles that are closely adhering and
tightly packed in a highly ordered system
• The motion of particles is highly restricted so
that they generally are incompressible
• Most expand lightly when heated
• May exhibit high or low density
Liquids
• Have no definite shape (assume the shape of its
container)
• Have a definite volume
• Have the ability to flow
• Have particles that are relatively close to one
another and are moderately ordered
• May have high or low density
• Incompressible
• Expand slightly when heated
Gases
• Have no definite shape and no definite volume
(always expand to fill its container)
• Have the ability to flow
• Have particles whose motion is unrestricted, so
they are independent and are relatively far apart
• Have a low density
• Highly compressible
• Expand greatly when heated
Plasma
• A plasma is a hot ionized gas consisting of
approximately equal numbers of positively
charged ions and negatively charged electrons.
• The characteristics of plasmas are significantly
different from those of ordinary neutral gases
• Because plasmas are made up of electrically
charged particles, they are strongly influenced
by electric and magnetic fields
Bose-Einstein Condensate
• A Bose-Einstein condensate is a group of atoms cooled to
absolute zero
• At T=0K, the atoms are hardly moving relative to each
other; they have almost no free energy to do so.
• The atoms begin to clump together, and enter the same
energy states.
• They become identical, from a physical point of view, and
the whole group starts behaving as though it were a single
atom.
• To make a Bose-Einstein condensate, you start with a cloud
of diffuse gas. Many experiments start with atoms of
rubidium.
• It doesn't form a lattice like a solid
Changes of State
• Melting – from solid to liquid
• Sublimation – from solid to gas
• Freezing – from liquid to solid
• Evaporation – from liquid to gas
• Condensation – from gas to liquid
• Deposition – from gas to solid
Properties of Matter
• Distinguishing characteristic of a substance that
is used in its identification and description.
• Each substance has a unique set of properties
that distinguishes it from all other substances.
• Two General Types:
• Physical
• Chemical
Properties of Matter
Physical Properties Chemical Properties
• variables that we can measure • the ability (or inability) of a
sample of matter to undergo a
without changing the identity of change in composition under
the substance being observed stated conditions
• examples: • involves the transformation of a
substance into another
color, mass, volume, density, substance; can be observed only
temperature, boiling point, when a substance changes into a
melting point, physical state at new substance.
a given temperature (solid, • example:
flammability (ability to catch fire
liquid, gas), odor, taste, easily), corrosiveness (or ability
to corrode), reactivity with
another substance to produce a
different substance
Comparison of Physical and Chemical
Properties
• A physical property tells what a substance is -- it
is white or it is green, it is odorless or it has a
sharp odor, it is hard or it is soft.
• A chemical property tells what a substance does
– it burns or it does not burn, it reacts with an
acid or it does not react with an acid.
Physical Properties of Matter
Intensive Properties Extensive Properties
• properties that do not depend • change when the amount of
on the amount of the substance changes
substance examples:
examples: length, volume, mass, area,
color, odor, taste, melting width
point, boiling point, density
State whether each property is
physical or chemical
• An iron nail is attracted to a magnet
• Charcoal lighter fluid is ignited with a match
• A bronze statue develops a green coating over
time
• A block of wood floats on water
Changes in Matter
Physical Change Chemical Change
 occurs when a substance • also known as a chemical
changes its appearance without reaction
changing its composition • occurs when a substance is
 examples: formed into another substance
phase change – process of with a totally different
changing from one physical composition and properties
state to another, grinding, • always accompanied by the
breaking a sheet of glass formation of a new substance
• examples:
rusting of iron, digestion,
burning, ripening of fruits
The following evidences can be used to guide you in
determining if a chemical change has occurred or not:
• The process involves the production of heat and
light
example: burning of wood
• A gaseous product is evolved
example: oxygen in the photosynthesis of plants
• A precipitate is formed
example: curdling of milk
• Mechanical energy or electrical energy is
produced
example: dynamite explosion and battery usage
What kind of change (physical or
chemical) does each process below
undergo?
• Formation of clouds
• Corrosion of iron
• Melting of sugar
• Burning of plastic
• Making ice cubes
• Boiling oil
Classification of Matter
Pure Substances Mixtures
 material that is made up of only • contains two or more
one substance with a definite substances
composition and a unique set of • can be separated into their
properties component substances physical
 cannot be broken down means
physically into simpler • Have no definite proportion or
substances composition
 can be elements or compounds • may be heterogeneous or
homogeneous
Classify as a pure substance or a
mixture
• Blueberry muffin
• Ice
• Aluminum foil
Pure Substances
Elements Compounds
 simplest substance that makes • result from the combination, in
up all matter a definite proportion by mass,
 a substance made up of only a of two or more elements
single type of atom • this gives rise to a substance
 cannot be broken down into with properties which are
simpler substances different from those of the
combining elements
• Can be separated into their
component substances by
chemical means
Classify as a compound or an element
• Silicon chip
• Hydrogen peroxide
Mixtures
Homogeneous Heterogeneous
• has uniform composition and • has parts separated by
properties throughout and distinct boundaries and
therefore has only one phase which have distinctly
different properties
• solutions (homogeneous • suspensions (heterogeneous
mixtures composed of two or fluids containing solid
more substances; in such a particles that are sufficiently
mixture, a solute is dissolved in large for sedimentation) or
another substance, known as a colloids (substances
solvent) microscopically dispersed
evenly throughout another
• Alloys – mixture of metals
one; consists of two separate
phases: a dispersed phase
and a dispersion medium)
Classify as homogeneous or
heterogeneous
• Vegetable soup
• Salt water
• Tea
• Tea with ice and a lemon slice
Distinguishing Between Compounds
and Mixtures
1) Compounds have properties distinctly different
from those of the substances that combined to
form the compound. The components of
mixtures retain their individual properties.
Distinguishing Between Compounds
and Mixtures
2) Compounds have a definite composition.
Mixtures have a variable composition.
Distinguishing Between Compounds
and Mixtures
3) Physical methods are sufficient to separate the
components of a mixture. The components of a
compound cannot be separated by physical
methods; chemical methods are required.
To Classify a Sample of Matter
1) Does the sample of matter have the same
properties throughout?
2) Are two or more different substances present?
3) Can the pure substance be broken down into
simpler substances?
Classify the following (element, compound,
homogeneous mixture, or heterogeneous
mixture)
• Vinegar
• Halo halo
• Copper wire
• Ice cream float
• Chocolate chip cookie
Discovery and Abundance of the
Elements
• 118 known elements:
 88 of the elements occur naturally
 30 of the elements have been synthesized
Abundance of Elements (in Atom
Percent) in the Universe
Abundance of Elements (in Atom
Percent) in the Earth’s Crust
Elemental Composition of the
Human Body (in Atom Percent)
Chemical Symbol
• One- or two-letter designation for an element
derived from the element’s name.
• Two letter symbols are often, but not always, the
first two letters of the element’s name.
Chemical Symbol
• First letter of a chemical symbol is always
capitalized and the second is not:
 H – hydrogen
 Ba – barium
 Co – cobalt
 Pb – lead
 Ag – silver
Latin Names
• For some elements, the symbol is derived from
the Latin name of the element:
 Ag – silver
 Au – gold
 Fe – iron
 Pb – lead
 Cu – copper
Atom
• The smallest particle of an element that can exist
and still have the properties of the element.
• The limit of chemical subdivision.
• Atoms are extremely small particles.
Molecule
• Group of two or more atoms that functions as a
unit because the atoms are tightly bound
together.
• The limit of physical subdivision.
• Behaves in many ways as a single, distinct
particle would.
• Diatomic molecule – contains two atoms
• Triatomic molecule – contains three atoms
• Tetraatomic, pentatomic, etc.
Homoatomic Molecule
• Molecule in which all atoms present are of the
same kind.
• Substance containing homoatomic molecules
must be an element.
 Examples: H2, O2, N2, Cl2, P4, S8
Heteroatomic Molecule
• Molecule in which two or more kinds of atoms
are present.
• Substance containing heteroatomic molecules
must be compounds.
 Examples: H2O, CO2, N2O4, C12H22O11
 Concept Check

Classify XeF4 as:

1) diatomic, triatomic, etc.

For each of the following chemical formulas,

a) H2SO4
two hydrogen; one sulfur; four oxygen
b) Fe2(CO3)3
two iron; three carbon; nine oxygen