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Content Benchmark P.8.A.6
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Students know matter is made up of tiny particles called atoms.  E/S

Matter, matter everywhere.
There's matter in your hair.
Matter in the air.
There's even matter in a pear!
There's liquid matter, solid matter, and matter that's a gas.
Even you are matter, because you have volume and mass!

- Poem by: Steve Tomecek, at

Within the realm of what we know exists - there is a lot of “stuff,” from stars and planets to oceans, wind and microscopic beings.  The way that we know this stuff exists is that we can experience it; it all has a mass and takes up some space or has “volume.”  All things that have these physical characteristics of mass and volume are considered “matter.” So, what is matter made of?  In spite of the many forms that matter may take, at its most basic level, all matter is composed of tiny particles called atoms

History of Composition of Matter

The earliest humans were curious about the various materials that they found around them—materials used to hunt for food, make clothing and medicines, and the myriad other manifestations of matter that made up their physical environment. 

The ancient Greek philosophers and scientists Empedocles and Democritus, who lived around 400 B.C., proposed one of the first documented theories that attempted to describe the things around us. Empedocles argued that all matter was composed of four elements: fire, air, water, and earth. He further theorized that the ratio of these four elements determined the properties of the matter

chemical reaction - ancient
Figure 1:  Early humans believed every material was made of
differing proportions of Fire, Air, Water and Earth

Early scientists also imagined that there might be a point at which you could no longer cut a material in half any further.  After much debate and experimentation, they agreed that indeed, an object could not be cut in half again and again indefinitely. They reasoned that sooner or later the object would become so small that it could not be divided again.  This raised the question of the existence of a smallest indivisible unit. They called this indivisible particle an “Atom.” (Atom is the Greek word meaning “not to be cut” or “indivisible”). 

For a very detailed explanation of the evolution of the idea of atoms as the building blocks of matter, see

Atoms and the Differentiation of Matter

If all matter is, at its most basic level, made of the same things—atoms—then what accounts for the seemingly infinite forms of matter we know to exist?  Much of the differentiation comes from the fact that we know of approximately 118 different types of atoms, called elements, which interact and combine to create millions of different compounds, all of which are used to make different forms of matter.  These different atoms are made of differing amounts of protons, neutrons and electrons whose proportions determine their physical and chemical characteristics.

For more information on the structure of atoms, see TIPS Benchmark P.8.A.7.

For more information on the arrangement of elements in the periodic table, see
TIPS benchmark P.8.A.2.

For more information on the formation of compounds and how atoms interact to form different substances, see TIPS benchmark P.8.A.4. 

Atoms and the Properties of Matter

Physical properties of matter vary based on the density of the atoms which make them up, as well as other characteristics (see Figure 3 below)).  Density is a relation of the mass of a substance (how many atoms are present) to the volume which the mass occupies. 

Some properties of matter:

  • color
  • taste
  • melting point
  • boiling point
  • density
  • luster
  • hardness
  • mass
  • volume
  • length
  • shape
  • reactivity

Figure 2: Some examples of more specific distinguishing properties of matter



Figure 3: Box A represents a greater density of atoms than Box B

The spacing of atoms and the ease with which they can move past each other affects the “state” or form in which the matter appears.  For example, in some substances the atoms are spaced far apart so they can easily move past each other and collide infrequently, in which case the substance would then be a gas.  If the atoms are compressed so closely that they can only vibrate slightly, the substance will appear as a solid.  Matter is able to be transformed into different states by the addition or removal of energy.  All of the matter that we experience in the universe is in one of five states: they are solid, liquid, gas, plasma or a newly discovered state, a Bose-Einstein condensate. 
For more information on the states of matter, see TIPS Benchmark P.8.A.1.

For more information on physical changes in matter, see TIPS Benchmark P.8.C.3.

To view the motion of atoms in the solid, liquid and gaseous states, visit this website:

Atoms and Classification of Matter
Scientists have come up with methods of describing and differentiating between the wide varieties of matter in our universe.  Because different substances are made of different combinations and types of atoms, they have distinct properties.  Scientists have created systems to describe and measure properties of matter. Matter is usually classified generally into different classes of substances and mixtures, and then further, more specifically, classified from there (see Figure 5).

Anything with mass and volume.

Matter with constant composition

Matter with variable composition

Substance made up of only one type of atom

Two or more elements that are chemically combined

Heterogeneous Mixture
Mixtures that are made up of more than one phase

Homogeneous Mixtures
Also called solutions.  Mixtures that are made up of only one phase

Examples - gold, silver, carbon, oxygen and hydrogen

Examples - water, carbon dioxide, sodium bicarbonate, carbon monoxide

Examples - sand, soil, chicken soup, pizza, chocolate chip cookies.

Examples - salt water, pure air, metal alloys, seltzer water.

Figure 4: General Levels of Classification of Matter

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Content Benchmark P.8.A.6

Students know matter is made up of tiny particles called atoms.  E/S

Common misconceptions associated with this benchmark

 1.  Students incorrectly believe that atoms can be seen with an optical microscope.

Atoms cannot be seen with an optical microscope. The extent of an atom’s small size is often not well understood. For example, there are about one million atoms across the width of human hair, but many students guess a number in the hundreds or thousands. With atoms being so small, it is not possible to see them optically.

Atoms however, have been “seen,” or more precisely, imaged using electron and atomic force microscopes. Electron microscopes use accelerated electrons instead of light to get increased resolution over optical microscopes. However, even electron microscopes can only see the largest atoms (e.g., uranium). Atomic force microscopes can image even smaller atoms by using nanotechnology. In essences, very small probes move over the atomic structure, providing a “pressure map,” in which the shape, size, and other properties can be inferred.

To learn more about the size and scale that can be measured by different types of microscopes, go to

2. Students incorrectly believe that particles possess the same properties as the materials they compose.

For example, atoms of copper are "orange and shiny," gas molecules are transparent, and solid molecules are hard. All atoms contain the same three parts, protons, neutrons and electrons, only in different proportions.  The properties of matter are determined by the interactions of the atoms with each other and the environment (e.g., how far apart the atoms are, what they are bonded to, and how they interact with light).

To learn more about this misconception, as well as other chemistry misconceptions, go to

Students incorrectly believe that atoms have characteristics of living things.

Many students still directly relate movement to life.  The fact that atoms have circulating electrons and a vibrating nature may lead students to believe that they are living entities.  Also, when learning about cells, students learn about a cellular eukaryotic nucleus.  When they hear that atoms also contain nuclei, they can become further entrenched in their misconception.  The movement in atomic particles is contributed to electrostatic forces, not life. 

Please see for more on this, as well as other related misconceptions.

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Content Benchmark P.8.A.6

Students know matter is made up of tiny particles called atoms.  E/S

Sample Test Questions

1st Item Specification: Identify that atoms are the smallest units of elements.

Depth Of Knowledge Level 1

  1. Elements exist of only one kind of
    1. molecule
    2. electron
    3. atom
    4. proton
  1. Which of the following is NOT one of the basic ideas of the atomic theory?
    1. Compounds are formed by the joining of atoms of two or more elements.
    2. Atoms of the same element contain the same number of protons and electrons.
    3. Atoms of different elements have eight electrons.
    4. All elements are composed of atoms.
  1. Which of the following is a true of all elements?
    1. They break down into a new element when reacting with acids.
    2. They can be changed into a new element with an electric current.
    3. They are all classified as metals and react with water to form a base.
    4. They cannot be divided into smaller parts by normal physical or chemical methods.
  1. Which of the following is the BEST description of an atom’s structure?
    1. Protons and electrons are grouped together in a random pattern.
    2. Protons and electrons are grouped together in an alternating pattern.
    3. A core of protons and neutrons are surrounded by electrons.
    4. A core of electrons and neutrons are surrounded by protons.
  1. Because zinc can combine with other substances, but cannot be changed into a simpler substance by an ordinary chemical process, zinc is classified as a (an)
    1. compound.
    2. element.
    3. acid.
    4. mixture.

Depth Of Knowledge Level 2

  1. Plants are made up of many atoms. Which is the BEST explanation of what happens to the atoms after a plant has died?
    1. The atoms stop moving until they are reanimated.
    2. The atoms recycle back into the surrounding environment.
    3. The atoms split into simpler parts and then combine to form other atoms.
    4. The atoms no longer exist once the animal has decomposed.
  1. When sulfuric acid, H2SO4, is broken down into separate elements, how many different atoms result?
    1. Two
    2. Three
    3. Six
    4. Seven
  1. Use the drawing below to answer the next question.


Which statement is true about the chemical sample shown in the drawing above?

  1. There are individual atoms present.
  2. There are three different elements present.
  3. All molecules are identical.
  4. It is a pure substance
  1. Use the drawing below to answer the next question. 
Drawing 1   Drawing 2    Drawing 3 Drawing 4


Which drawing represents a substance that is made up of atoms of different elements? 

    1. Drawing 1
    2. Drawing 2
    3. Drawing 3
    4. Drawing 4
  1. Use the drawing below to answer the next question.
Drawing 1  Drawing 2 Drawing 3 Drawing 4


Which drawing represents a substance that is made up of atoms of different elements? 

    1. Drawing 1
    2. Drawing 2
    3. Drawing 3
    4. Drawing 4

Constructed Response P.8.A.6

  1. In the early 1900's many scientists had turned their attention to investigating the structure of the atom and many models were proposed.  (A model is a simplified representation of an object.)  One early simple model of the atom is very similar to the model of the Solar System.
Text Box: 6  C  12.01    Use this information, taken from the periodic table, to determine the correct number of each of the components.
  1. Draw a sketch of a simple model of a carbon atom AND labeling its components. 
  2. If all atoms of different elements contain the same kind of components, why do elements have different chemical and physical properties?  Justify your answer with a complete statement.

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Content Benchmark P.8.A.6

Students know that matter is made up of tiny particles called atoms. E/S

Answers to Sample Test Questions

  1. C, DOK level 1
  2. C, DOK level 1
  3. D, DOK level 1
  4. C, DOK level 1
  5. B, DOK level 1
  6. B, DOK level 2
  7. D, DOK level 2
  8. B, DOK level 2
  9. A, DOK level 2
  10. D, DOK level 2


Constructed Response 3-point Answer and Score Rubric:




3 points


Response addresses all parts of the question clearly and correctly.
Student demonstrates a complete understanding of the structure of an atom by sketching a diagram that shows all of the following: (a) The nucleus or proton/neutron cluster, labeled as "nucleus" or “protons and neutrons" or “proton". (b) 6 labeled “electrons”. (c) An indication that the 6 electron(s) orbits around the nucleus (by showing 2-4 electron arrangement in two circles around the nucleus). (d) Indicates that the model of the carbon atom has 6 protons, 6 neutrons and 6 electrons. Explains in a complete sentence that the chemical and physical properties are due to the number and position of the protons and electrons.

2 points

Response addresses all parts of the question and includes only minor errors.

1 point

Response does not address all parts of the question.

0 points

Response is totally incorrect or no response provided.


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Content Benchmark P.8.A.6

Students know matter is made up of tiny particles called atoms.  E/S

Intervention Strategies and Resources

The following is a list of intervention strategies and resources that will facilitate student understanding of this benchmark.

1. Mystery: Structure of the Atom - A Case for Indirect Evidence

Because we can’t “see” atoms, students may wonder how we know matter is made of these particles.  This website provides four activities which use everyday items to illustrate how scientists can use indirect evidence to figure out the properties of substances to small to see by how they interact with other substances.  

The access the lab information visit

What is Matter? Worksheets

On this website Jefferson Labs provides worksheets along with their answer keys which can be used to provide reinforcement when studying the parts of atoms, the building blocks of matter.

To access these worksheets, go to

3. Describing Matter Vocabulary Activities

Hosted by Quia, the website provides a medium for educators to create and share educational games, quizzes, and activities, this application provides three different mediums for practicing vocabulary related to matter.  Students can test their knowledge of matter related vocabulary and continue to familiarize themselves with terminology through flashcards, a matching game, concentration game and a word search. 

This application can be found at

Particle Nature of Matter Activity

Need some ideas for activities that address the particle nature of matter?  The following website provides student handouts and teacher keys for many activities which can be used to access and reinforce student understanding of the particulate nature of matter.  These activities address molecular motion, density, states of matter, phase changes, and they address misconceptions about the spacing of particles in different states of matter.

To download this activity, go to

Harcourt School States of Matter Simulation

On this website, Harcourt provides a wonderful interactive simulation on how temperature affects the spacing and movement of particles when a substance moves between a solid, liquid and gaseous state.  The students can witness at the atomic level what is happening to the atoms.

To view the simulation visit

6. Ask Grandpa – Interactive trip following the discovery of the composition of matter

The Ask Grandpa website provides a historical tour of experimental research on the topic of matter and atom discovery.  The information is presented by cartoon images of the scientists and the information regarding their discoveries is simple and straight to the point.

For this interactive tour go to

7. Vision Learning – Dalton’s Playhouse

This is another website which helps students understand the history and happenstance behind the discovery of the atom.  In this virtual tour of the scientist’s laboratories, students are able to take part in the experiments that led to the discovery of the atom.  After each experiment, students are asked a series of questions to check their understanding.  After completing the virtual labs successfully, the students can even print a certificate.

Visit Dalton’s Playhouse at

8. How Big is an Atom?

This website provides a very simple, but powerful activity which gives students a better idea as to how small atoms really are.  The students are asked the following question. If they are given an atom of gold for every second since the big bang, would they be rich?  You’ll have to look at the website to find out…

To find the answer, visit

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Benchmark Related Vocabulary

Atomic theory