Digital Inquiry - How Matter Changes

Last updated 7 months ago

8 questions

How do the elements compare to one another in terms of changing states of matter?

What type of energy is necessary for each element to change states, or phases?

VIDEO: Mystery Mud

Many of us have seen water change from a solid to a liquid and from a liquid to a gas, and we know that other substances undergo similar transformations. These changes are usually a result of either heating or cooling. 

In this video, students visit a lab at the Massachusetts Institute of Technology where scientists study a substance that changes state without a change of temperature.

The video provides a good view of how primary scientific research can inform choices for engineers.

How does the mystery mud become solid without thermal energy?

What property of the matter makes it different from other types of matter?

SIMULATION: Melting & Boiling

Click the link above to observe how temperature affects particles in matter.

How does temperature affect the energy of the particles?

ARTICLE: Melting Gold

In its purest form, gold typically requires temperatures of 1,948 degrees Fahrenheit (1,064 degrees Celsius) to liquefy. Now, a team of researchers from the Chalmers University of Technology in Sweden may have stumbled upon a way to melt the precious metal at room temperature.

For those not clear on the physics behind the phenomenon of melting, here is a brief tutorial. Solids, as you may know, can maintain size and shape under constant conditions because their atoms, or molecules, do not have enough energy to pull apart. When an external source of energy is introduced, it gets the molecules excited and causes the tight structure to break down, allowing them to start moving freely. This results in a change of state from solid to liquid, or what we refer to as melting. Researchers mostly use heat, or in some cases pressure, to trigger the change. However, the Swedish team managed to accomplish the feat using a different energy source – an electric field.

For their study, Dr. Ludvig de Knoop and his team placed a gold sample under an electron microscope (EM). Unlike optical microscopes that depend on visible light, EM’s use a beam of accelerated electrons as a source of illumination, making them powerful enough to see individual atoms. To investigate if the electrical field had any impact on the metal’s molecules, the researchers gradually increased its intensity while using the highest magnification.

"We wanted to see what happens to gold when it is under the influence of an extremely high electric field," de Knoop told Newsweek. "A known effect when applying such high electric fields on metals is that they evaporate, that is, they boil off from the solid metal."
Upon examining the atoms in recordings taken from the EM, de Knoop noticed something very unexpected – the surface layers of the gold sample had melted, even though the experiment had been conducted at room temperature. The change was easily reversed by simply turning off the electric field.

"It wasn’t until later, when we analyzed the data and the recorded movies, that we understood that we had witnessed something new and spectacular," de Knoop said. "The big surprise with our work was that the outermost few atomic surface layers of gold melted before they evaporate.”

The researchers, who published their findings in the journal Physics Review Materials on August 22, 2018, believe the electrical field caused the gold atoms to become excited and lose their structure, breaking the strong bond between them. However, de Knoop said, “IIt is] Important to note is that it is only the 2-3 outmost atomic layers that experience the electric field, further into the gold cone the electric field is zero and the atoms are ordered and structured in their usual way. This is an important difference compared to melting gold by increasing the temperature."

Though the technique needs to be investigated further, the team believes it could help revolutionize the field of material sciences and have numerous applications in the development of nanodevices like sensors, catalysts, and transistors. “There could also be opportunities for new concepts for contactless components," said study co-author Professor Eval Olsson.

How do jewelers and scientists change solid gold into liquid gold under normal conditions?

How were scientists able to melt solid gold without thermal energy?

___________  is anything that has mass and takes up space.  There are three _____________________ : solid, liquid, and gas.  Matter can change states by increasing or decreasing the amount of ___________________ .

All matter can change states, but each type of matter has a boiling, freezing, and __________________  unique to its particles.  Hydrogen is a gas that can become a liquid at -253°C while solid carbon can only become liquid under extreme heat and pressure.

 Water exists in all three states on Earth making it easy to ____________  phase changes.  Liquid water freezes at 0°C and becomes ________________  at 100°C.

Even though matter changes states by increasing and decreasing the amount of thermal energy, scientists are always making new discoveries.  Special fluids, like mystery mud, have microscopic iron particles.  When magnetic _______________  occurs, the particles are forced into a fixed pattern of columns and clusters.  The liquid becomes a solid without a change in thermal energy!

Understanding how matter changes __________  helps scientists use matter in different ways and explore alternative technologies for the future.  Scientists and jewelers who work with precious metals have recently discovered how to melt gold at room temperature using ________________!