# data[].attributes.body
This short video teaches students how atoms are the smallest particles of elements and how each element is comprised of one type of atom.

# data[].attributes.attachment_link.title
Atoms & Elements | UNC-TV Science | PBS LearningMedia

# data[].attributes.attachment_link.description
Atoms are the smallest possible type of matter. Find out about atoms and elements with this animations.

# data[].attributes.body
This video shows shows students how burning a piece of steel wool leads to an increase in mass.

# data[].attributes.attachment_link.readable_text
Description: This is an excellent phenomenon to discuss chemical reactions and the conservation of mass. Steel wool is burned leading to an increase in mass. When doing this in class show the students the burning steel wool to begin with and have them predict the change in mass. Most students believe the mass will either increase or decrease. This phenomenon can be used at the beginning of a unit on chemical reactions and students can investigate their individual models. (e.g. mass comes from fire, oxygen, carbon, etc.)
Web Resources: Combustion of Iron Wool - CFNS Experiment 36

# data[].attributes.attachment_link.description
Description: This is an excellent phenomenon to discuss chemical reactions and the conservation of mass. Steel wool is burned leading to an increase in mass. When doing this in class show the students the burning steel wool to begin with and have them predict the change in mass.

# data[].attributes.body
This video clip shows students how bond energy is released in a chemical reaction when a sample of sodium acetate is activated from touching a metal disc on the plastic of the heat pack.

# data[].attributes.attachment_link.readable_text
Description: This phenomenon uses a supersaturated solution of sodium acetate. Clicking the metal disc releases a small number of crystals of sodium acetate which act as nucleation sites for the crystallization of the sodium acetate into a hydrated salt. Energy is released from the crystal lattice. The heating pack can be placed in boiling water and the sodium acetate can be dissolved again. This phenomenon shows how bond energy can be released. It also shows the importance of chemical engineering and could lead to a section where students design a device (or application) of their own.

Web Resource: Chemical Heat Pack - Wikipedia, Snappy Heat - Amazon

# data[].attributes.attachment_link.title
Reusable Heat Packs - The Wonder of Science

# data[].attributes.attachment_link.description
Description: This phenomenon uses a supersaturated solution of sodium acetate. Clicking the metal disc releases a small number of crystals of sodium acetate which act as nucleation sites for the crystallization of the sodium acetate into a hydrated salt. Energy is released from t

# data[].attributes.body
In this simulation, students balance chemical equations using scales to show balance on sides of reactants and products. There is also an extension link for additional practice problems for students to predict products of chemical reactions.

# data[].attributes.attachment_link.description
How do you know if a chemical equation is balanced? What can you change to balance an equation? Play a game to test your ideas!

# data[].attributes.body
In this hands-on activity, students create a 3-D model of the Periodic Table using sticks of spaghetti to observe the trends in atomic properties that underlie the arrangement of elements into periods and families.

# data[].attributes.attachment_link.readable_text
Start by choosing one atomic property to scale and plot. For instance, you might choose atomic radius, ionization energy, electron affinity, electronegativity, density, melting point, boiling point, etc. For our example, we've used the calculated atomic radius of elements.
(Note: Depending on the property you want to plot, you may need to find a table or chart that has your chosen data. A sampling of resources can be found in the Resources section below.)

Once you've found a table to work from, analyze the information available and decide on a method to scale your data so it can be converted into an appropriate length of spaghetti. (A piece of spaghetti is usually about 25 cm long.) Note that your data might be in units not usually associated with standard lengths-for example, kilojoules per mole, electron volts, picometers, or even no units, such as for electronegativity.

Calculate the scaled length for each spaghetti stick to be used (a calculator might be helpful), and then measure and break spaghetti pieces into appropriate lengths to represent the relative scaled property of each element (see photo below). If a few of your spaghetti sticks need to be longer than 25cm, just tape an extra piece to the end to make up the difference. If more than a few need extensions, change your conversion method for scaling your strands.

In our example, we did this by creating a table of atomic radii in picometers (pm) that we scaled to centimeters (cm). This represents a 10 ¹⁰ times increase in length, since 1 pm is 10⁻¹² meters and 1 cm is 10⁻¹⁰ meters. A simple way to make this conversion mathematically is to divide each value by 10, and then let centimeters stand for picometers. The table below, showing data for the elements lithium to neon, is a sample of the calculations we used to find the lengths of the sticks of spaghetti we needed for our table.

When you've measured each piece of spaghetti needed, insert each stick of spaghetti into the appropriate punched hole in your cardboard periodic table (see photo below). Look at the pattern and shape of your table of spaghetti. Can you pick out any trends? How do the rows and columns compare?

# data[].attributes.attachment_link.description
Start by choosing one atomic property to scale and plot. For instance, you might choose atomic radius, ionization energy, electron affinity, electronegativity, density, melting point, boiling point, etc. For our example, we've used the calculated atomic radius of elements.

# data[].attributes.body
This article teaches about the basics of temperature and how it relates to average kinetic energy of particles. The article uses snow as an example so that students can note the phenomena of falling and melting snow on the ground.

# data[].attributes.attachment_link.readable_text
Temperature describes how hot or cold something is. An object's temperature represents its average thermal energy-how fast or slowly its atoms or molecules are moving.

Subjects

Chemistry, Earth Science, Meteorology, Physics

Image

Thermometer in the Snow

Electronic thermometers, like this, use differences in the flow of electricity to gauge temperature changes.

Photograph by Dmitry Naumov/Shutterstock

Temperature describes how hot or cold something is. An object's temperature represents its average thermal energy-how fast or slowly its atoms or molecules are moving. Water molecules of boiling water, for instance, move much faster than frozen water molecules, so boiling water has more thermal energy. This is why boiling water has a higher temperature than ice.

Temperature is measured in three different ways. Most of the world measures temperature with degrees Celsius, which is part of the metric system. In this system, 0°C marks water's freezing temperature and 100°C marks its boiling point. Most scientists use the Celsius scale when measuring temperatures in experiments.

The United States and a few other countries still use the Fahrenheit scale for nontechnical purposes, such as TV weather reports. In this system, 32°F marks the temperature at which water freezes and 212°F marks its boiling point.

The third system is predominantly used by scientists and is called the kelvin scale. It is based on the coldest temperature possible-absolute zero-which is equal to 0 kelvin. In this system, water freezes at 273.15K and boils at 373.15K. The degree symbol is not used when expressing temperatures in the kelvin scale.

Humans are not very good at gauging temperature. For example, if a person were to simultaneously touch a book and a metal pipe that are both at room temperature, the metal pipe would feel cooler. That is because metal is a better conductor of heat than paper, so a metal pipe draws heat away from the skin faster than a book. That makes the pipe feel cooler than the book even though it is exactly the same temperature.

Temperature is measured with a thermometer. The liquid thermometer was one of the earliest types of thermometer. These instruments measure temperature with the varying volume of a liquid, such as mercury, encased in a narrow glass tube. The liquid expands when it gets warmer and contracts when it cools down, rising and falling in the tube. Markings on the tube show the temperature.

Liquid thermometers are still used today for some purposes, but there are now other kinds of thermometers available, including ones that operate electronically. These instruments work by detecting variations in the flow of electricity through the thermometer's circuitry caused by changes in temperature.

Media Credits

The audio, illustrations, photos, and videos are credited beneath the media asset, except for promotional images, which generally link to another page that contains the media credit. The Rights Holder for media is the person or group credited.

Director

Tyson Brown, National Geographic Society

Author

National Geographic Society

Production Managers

Gina Borgia, National Geographic Society

Jeanna Sullivan, National Geographic Society

Program Specialists

Sarah Appleton, National Geographic Society, National Geographic Society

Margot Willis, National Geographic Society

other

Last Updated

October 19, 2023

For information on user permissions, please read our Terms of Service. If you have questions about how to cite anything on our website in your project or classroom presentation, please contact your teacher. They will best know the preferred format. When you reach out to them, you will need the page title, URL, and the date you accessed the resource.

Media

If a media asset is downloadable, a download button appears in the corner of the media viewer. If no button appears, you cannot download or save the media.

Text

Text on this page is printable and can be used according to our Terms of Service.

Interactives

Any interactives on this page can only be played while you are visiting our website. You cannot download interactives.

# data[].attributes.attachment_link.description
Temperature describes how hot or cold something is. An object's temperature represents its average thermal energy-how fast or slowly its atoms or molecules are moving.

# data[].attributes.body
This video and simulation has students observe what happens to particles when an ice cube melts or when water boils. Emphasis is placed on particle movement with changes in temperature.

# data[].attributes.attachment_link.title
Phase Changes | Phases of Matter | PBS NC Science | PBS LearningMedia

# data[].attributes.attachment_link.description
What happens to particles when an ice cube melts or water boils? Find out with this animation.

# data[].attributes.body
This simulation allows students to see the electron movement between metal atoms and thus how a metallic bond forms. Students can also investigate the properties of the electron movement by changing the temperature of the metal.

# data[].attributes.attachment_link.title
Drude Model Conduction | PBS LearningMedia

# data[].attributes.attachment_link.description
Learn how electrons flow through a metal conductor using this interactive simulation of the Drude Model of electron flow. In this simulation, electrons are added to the right side of the thin metal plate. These surface electrons create an electric field that pushes the electrons inside the metal to the left.

# data[].attributes.body
This video teaches students to learn a song to remember what fusion is and how it relates to freezing. Phase diagrams are also explored to teach how potential and kinetic energies change during phase changes.

# data[].attributes.attachment_link.title
The Heat of Fusion of Water | PBS LearningMedia

# data[].attributes.attachment_link.description
This video segment from Regents Review 2.0 describes the heat of fusion of water. Listen to this fun song to get a better grasp of fusion.