N o r t h E a st I n d ep en d e nt S c h o o l D i st ric t
IPC
Unit 4: Properties of Matter
Clarifying Statements
May, 2006
Matter is a term used to describe anything that has mass and volume. Matter is
made of tiny particles called atoms. Students must have a basic understanding of
atomic structure in order to correctly classify matter. Atoms are composed of
even smaller particles known as protons, neutrons and electrons. Protons and
neutrons are located inside the nucleus and are responsible for the mass of the
atom, as they both have a mass of 1 a.m.u. (actual equivalent of 1.67x10-27 kg).
Protons have a charge of +1 (actual equivalent of +1.602 x 10-19 coulombs) while
neutrons have no charge. Electrons are located in a “cloud” surround the nucleus
and have no real mass but a charge of -1. The electric force of attraction between
the nucleus and electrons holds the atom together.
Classification of Matter
Matter can be divided into two categories: mixtures and substances.
1. Mixtures contain more than one kind of matter and can be separated by
physical means (sorting, filtering, heating, cooling, etc…). Homogeneous
mixtures have the same throughout (such as chocolate ice cream).
Heterogeneous mixtures do not have a uniform consistency throughout
(such as chicken noodle soup).
2. Substances, however, are chemically bonded and cannot be separated by
physical means. Elements are substances that are made of only one type of
atom. Elements, such as oxygen, can be found on the periodic table.
Clarifying statements are intended to deepen teachers’ understanding of science concepts and serve as a guide for instructional
design. They are not intended to serve as student instructional materials.
This publication is the property of North East Independent School District. Duplication in whole or in part, outside of NEISD, is
prohibited without express written permission from NEISD.
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N o r t h E a st I n d ep en d e nt S c h o o l D i st ric t
IPC
Unit 4: Properties of Matter
Clarifying Statements
May, 2006
3. Compounds are substances that are made up of two or more elements.
Compounds such as table salt (NaCl) require chemical reactions to separate
them. Compounds have properties that are different from their component
elements, and always contain the same ratio of component atoms. For
example, water has quite different properties than hydrogen and oxygen (its
component elements) and the formula for water is always the same (H20).
Matter
Substance
Element
Compound
Mixture
Homogeneous
Heterogeneous
Properties of matter
Matter can be distinguished by its chemical properties and its physical
properties. Chemical properties such as reactivity and flammability are discussed
in further detail in future units. Physical properties can be observed or measured
without changing the composition of the matter. These properties include color,
texture, shape, melting point, boiling point, and state (solid, liquid, or gas). It is
important that students investigate the physical properties of density, viscosity
and buoyancy during this unit.
Density is a property that describes the relationship between mass and
volume. The density of an object is calculated by dividing the object’s mass by its
volume.
Clarifying statements are intended to deepen teachers’ understanding of science concepts and serve as a guide for instructional
design. They are not intended to serve as student instructional materials.
This publication is the property of North East Independent School District. Duplication in whole or in part, outside of NEISD, is
prohibited without express written permission from NEISD.
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N o r t h E a st I n d ep en d e nt S c h o o l D i st ric t
IPC
Unit 4: Properties of Matter
Density
=
mass
volume
Clarifying Statements
May, 2006
D=m
v
Density is usually measured in grams per cubic centimeters
(cm3) or grams per milliliters (ml). The volume of a
rectangular solid or cube can be calculated by the relationship
of length x width x height; and the volume of a liquid can be
measured with a graduated cylinder. The volume of an
irregularly shaped object or a liquid can be found by the
water displacement method where the object is submerged
in water and the volume of the displaced water is measured.
Students should be aware of the fact that the density of
water is 1 g/ml or 1 g/cm3 . The table at right shows the densities of some common
substances.
Knowing the density of an object can help determine if the object will float or sink
in a liquid. Objects or substances will float if they have a lower density than the
liquid they are submerged in. Therefore, objects or substances with a density
greater than 1 g/cm3 will sink in water and those with a density less than 1 g/cm3
float in water.
Clarifying statements are intended to deepen teachers’ understanding of science concepts and serve as a guide for instructional
design. They are not intended to serve as student instructional materials.
This publication is the property of North East Independent School District. Duplication in whole or in part, outside of NEISD, is
prohibited without express written permission from NEISD.
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N o r t h E a st I n d ep en d e nt S c h o o l D i st ric t
IPC
Unit 4: Properties of Matter
Clarifying Statements
May, 2006
Buoyancy is a physical property of fluids (liquids and gases) that explains why an
object submerged in a fluid appears to weigh less than its true weight. Buoyant
force is a measure of the upward force a fluid exerts on an object. According to
Archimedes' principle, the buoyant force on an object is equal to the weight of
the fluid displaced by the object. Therefore, when an object floats in a fluid it
displaces the amount of fluid that is equal to the weight of the object. Students
should be able to use Archimedes principle to explain why steel boats float even
though steel is denser than water..
Viscosity is a physical property of fluids that measures the resistance of a
fluid to flow. High viscosity fluids (such as honey) take longer to pour from one
container to another. The size and shape of a fluid’s molecules determine its
viscosity. A liquids’ viscosity decreases as its temperature increases. For example,
cold maple syrup is more viscous than warm syrup. Gases, however, experience the
opposite effect because their viscosity increases as their temperature increases.
This is due to the fact that the increase in temperature causes more collisions
between the molecules, which results in an increase in friction, and therefore
viscosity.
Clarifying statements are intended to deepen teachers’ understanding of science concepts and serve as a guide for instructional
design. They are not intended to serve as student instructional materials.
This publication is the property of North East Independent School District. Duplication in whole or in part, outside of NEISD, is
prohibited without express written permission from NEISD.
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N o r t h E a st I n d ep en d e nt S c h o o l D i st ric t
IPC
Unit 4: Properties of Matter
Clarifying Statements
May, 2006
History of the Atomic Theory
The historical development of the atomic theory has not been tested on the
TAKS and therefore should be presented only briefly (less than one class period).
Student must be aware that atoms are the building block of all substances in the
universe. An atom may be defined as the smallest particle of an element that still
retains the element’s properties. We can think of the basic structure of an atom
as a positively charged nucleus surrounded by negatively charged electrons orbiting
in energy levels (or shells). As scientific research progresses, theories explaining
the structure of atoms continue to change. A brief history of the atomic theory is
as follows:
Dalton Model (1807) – Atoms are small, solid, indivisible spheres with a uniform
density.
Thompson Model (1903) – The atom consists of a cloud of evenly distributed
positive and negative charges. (Thompson discovered the electron).
Rutherford Model (1911) – The atom consists of (-) electrons surrounding a tiny
nucleus which contains (+) protons and neutral neutrons.
Clarifying statements are intended to deepen teachers’ understanding of science concepts and serve as a guide for instructional
design. They are not intended to serve as student instructional materials.
This publication is the property of North East Independent School District. Duplication in whole or in part, outside of NEISD, is
prohibited without express written permission from NEISD.
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N o r t h E a st I n d ep en d e nt S c h o o l D i st ric t
IPC
Unit 4: Properties of Matter
Clarifying Statements
May, 2006
Bohr Model (1915) – Electrons exist in orbits of a specific energy which surround
the nucleus. When they absorb energy, they can move to a higher level (an excited
state) and can give off energy in the form of light when they move back to their
original level (their ground state). There is mostly empty space between the
nucleus and the electrons.
Electron Cloud Model (1926) – Electrons may be found in a region known as a
“cloud” that surrounds the nucleus.
Spectral analysis
This topic should only be addressed briefly through a class discussion and possibly
a demonstration for no more than half a class period.
Spectral analysis is a visual representation of the emission lines of certain metal
compounds. Each individual atom or compound gives off its own unique wavelengths
of light when excited, and these wavelengths can be examined through spectral
analysis. By studying these emission line produced by the characteristic
wavelengths, scientists can use the information to identify the elements and
compounds that make up objects such as stars.
Clarifying statements are intended to deepen teachers’ understanding of science concepts and serve as a guide for instructional
design. They are not intended to serve as student instructional materials.
This publication is the property of North East Independent School District. Duplication in whole or in part, outside of NEISD, is
prohibited without express written permission from NEISD.
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N o r t h E a st I n d ep en d e nt S c h o o l D i st ric t
IPC
Unit 4: Properties of Matter
Clarifying Statements
May, 2006
During the first half of the 19th century, scientists studied the spectra of flames
produced by different chemical elements. Soon it was deduced that each element
produces a characteristic pattern of characteristic major and minor emission lines.
One of the most triumphs of spectroscopy during the 19th century was the
discovery of helium. An emission line was first observed in the solar corona during
the eclipse of August 18, 1868 and therefore Helium was named from the Greek
word “Helios”.
In the 1830’s advancements in chemistry led to the discovery that color could be
produced by burning a metallic salt. Chemists applied this discovery to "qualitative
Clarifying statements are intended to deepen teachers’ understanding of science concepts and serve as a guide for instructional
design. They are not intended to serve as student instructional materials.
This publication is the property of North East Independent School District. Duplication in whole or in part, outside of NEISD, is
prohibited without express written permission from NEISD.
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N o r t h E a st I n d ep en d e nt S c h o o l D i st ric t
IPC
Unit 4: Properties of Matter
Clarifying Statements
May, 2006
analysis" and began using flame tests to categorize new elements based on their
unique emissions spectra. The field of pyrotechnics developed as these compounds
were utilized in the production of fireworks.
Phases (States) of Matter
One of the most important graphs that students must be able to interpret is the
one showing the relationship of temperature and heat energy as they relate to
phase changes.
After students understand that either the absorption or release of energy is
required for the substance to undergo a physical change, they must become
familiar with the terms that describe these energy changes. Students should
already be familiar with most of the following phase changes with the possible
exception of sublimation.
Clarifying statements are intended to deepen teachers’ understanding of science concepts and serve as a guide for instructional
design. They are not intended to serve as student instructional materials.
This publication is the property of North East Independent School District. Duplication in whole or in part, outside of NEISD, is
prohibited without express written permission from NEISD.
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N o r t h E a st I n d ep en d e nt S c h o o l D i st ric t
IPC
Unit 4: Properties of Matter
Clarifying Statements
May, 2006
Evaporation describes the change of a substance from a liquid to a gaseous state
through an increase in heat energy. Liquid water turning into water vapor is an
example of evaporation.
Vaporization also describes the change of a substance from a liquid to a gaseous
state through an increase in heat energy. Boiling water to produce steam is an
example of vaporization.
Condensation is the change of a substance from a gas to a liquid by releasing heat
energy. An example of condensation includes the drops of water that form on the
outside of a cold drink.
Freezing is the change of substance from a liquid to a solid through the release of
heat energy. Liquid water forming solid ice is an example of freezing.
Melting is the change of a solid to a liquid by an increase in heat energy. Ice cubes
turning into liquid water is an example of melting.
Sublimation is the change of a substance from a solid directly to a gas without
going through the liquid stage. Dry ice and freezer burn are examples of
sublimation.
Clarifying statements are intended to deepen teachers’ understanding of science concepts and serve as a guide for instructional
design. They are not intended to serve as student instructional materials.
This publication is the property of North East Independent School District. Duplication in whole or in part, outside of NEISD, is
prohibited without express written permission from NEISD.
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N o r t h E a st I n d ep en d e nt S c h o o l D i st ric t
IPC
Unit 4: Properties of Matter
Clarifying Statements
May, 2006
Changing the state of a substance does not change its composition or mass.
Changes in state do, however, change the density of a substance. In general, a
substance becomes less dense as it increases in thermal energy and changes phase
from a solid to a liquid to a gas. Water is unique in that it is the densest as a liquid
at 4˚C. Ice is actually less dense than water, which is why ice floats on water. Due
to the polar nature of water molecules, they form hexagon structures separated
by empty spaces as they freeze, causing ice to be less dense than water.
Students should be familiar with the characteristics of substances in each state
of matter. Solids have a definite shape and volume while liquids have a definite
volume, but take the shape of the container. Gases have no definite shape and can
be compressed or can spread evenly throughout a container.
Plasma is a fourth state of matter that cannot be described through the use of a
phase change diagram. Plasma is the most common state of matter in the universe,
however it is rarely found on earth. The plasma state occurs at temperatures of
Clarifying statements are intended to deepen teachers’ understanding of science concepts and serve as a guide for instructional
design. They are not intended to serve as student instructional materials.
This publication is the property of North East Independent School District. Duplication in whole or in part, outside of NEISD, is
prohibited without express written permission from NEISD.
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N o r t h E a st I n d ep en d e nt S c h o o l D i st ric t
IPC
Unit 4: Properties of Matter
Clarifying Statements
May, 2006
more than 10,000 degrees Celsius, which explains the fact that the sun consists of
plasma. Plasma can be seen on earth in the form of lightening.
Periodic Table
The periodic table is a representation of the elements arranged in columns based
on similar properties. Elements are listed in this order on the periodic table
according to the periodic law which states that when elements are arranged in
order of increasing atomic number (the number of protons in the nucleus),
similarities in their properties will occur in a regular pattern.
Horizontal rows in the periodic table are called periods. The number of protons in
atom has increases from left to right across a period, as do its number of
electrons. All of the elements within a period have the same number of atomic
orbitals, also known as energy levels. The maximum number of electron orbitals,
(also known as electron shells) for any element is seven.
Students should know that valence electrons (the electrons in the outermost
energy level) determine the chemical properties of atoms. Atoms of elements in
the same group or column (family) have the same number of valence electrons, and
these elements have resulting similar properties. The roman numerals at the top
of each group help indicate the number of valence electrons in the elements in that
group.
Clarifying statements are intended to deepen teachers’ understanding of science concepts and serve as a guide for instructional
design. They are not intended to serve as student instructional materials.
This publication is the property of North East Independent School District. Duplication in whole or in part, outside of NEISD, is
prohibited without express written permission from NEISD.
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N o r t h E a st I n d ep en d e nt S c h o o l D i st ric t
IPC
Unit 4: Properties of Matter
Clarifying Statements
May, 2006
Students should also know that elements are reactive because their outermost
energy levels are only partially filled. Atoms that do not have completely filled
outermost energy levels may undergo a process called ionization. This means that
they may gain or lose valence electrons in order to obtain a full outermost energy
level. If an atom gains or loses electrons, it no longer contains the same number of
electrons as it does protons. Because the charges do not cancel completely as they
did before, the resulting ion that forms has a net electric charge.
It is also important for the students to know that the atomic number indicates the
number of protons in an atom and therefore the number of electrons in a neutral
atom. The atomic mass of an atom equals the number of protons plus the number
of neutrons.
Students must be aware that neutrons can be added to an atom without affecting
its number of protons and electrons. Many elements have only one stable form,
while other elements have different “versions” of their atoms. Each of these
versions has the same number of protons and electrons but a different number of
neutrons. These different versions are called isotopes and vary in mass but not in
element identity (because they each have the same number of protons).
Some isotopes are more common than others. The atomic mass on the periodic
table is an average of all the masses of the isotopes.
Clarifying statements are intended to deepen teachers’ understanding of science concepts and serve as a guide for instructional
design. They are not intended to serve as student instructional materials.
This publication is the property of North East Independent School District. Duplication in whole or in part, outside of NEISD, is
prohibited without express written permission from NEISD.
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N o r t h E a st I n d ep en d e nt S c h o o l D i st ric t
IPC
Unit 4: Properties of Matter
Clarifying Statements
May, 2006
Drawing Atomic Structures
The Bohr model, shown as follows, consists of the energy levels of the atom and
the electrons that each contain.
Lewis dot structures like those below identify the valence electrons located in the
outermost energy level.
Clarifying statements are intended to deepen teachers’ understanding of science concepts and serve as a guide for instructional
design. They are not intended to serve as student instructional materials.
This publication is the property of North East Independent School District. Duplication in whole or in part, outside of NEISD, is
prohibited without express written permission from NEISD.
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