Science on This Day: November 23 | Real Gases, the Periodic Table and the First Jukeboxes
November 23 brings together three stories that show how science changes the way we understand and experience the world. Johannes Diderik van der Waals helped explain why real gases do not always behave as simple mathematical models predict. Henry Moseley used X-rays to reveal a better way to organise the chemical elements. And in 1889, a coin-operated phonograph in San Francisco offered customers a new way to listen to recorded music.
These events connect physics, chemistry, materials science and technology. They also show students that scientific progress often begins when someone looks more closely at something familiar and asks whether the accepted explanation is quite good enough.
November 23, 1837: Johannes Diderik van der Waals and the behaviour of real gases
Dutch physicist Johannes Diderik van der Waals was born on November 23, 1837, in Leiden, the Netherlands. He later developed an equation of state that improved scientists' understanding of gases and liquids. His work was recognised with the 1910 Nobel Prize in Physics. The Nobel Prize biography of van der Waals explains how he investigated the forces between molecules and developed a model that could describe both gases and liquids.
Many students first meet gases through the ideal gas law:
[PV=nRT]
This relationship connects pressure, volume, temperature and the amount of gas. It is an extremely useful model, but it makes simplifying assumptions. In an ideal gas, particles are treated as if they occupy negligible volume and do not exert intermolecular forces on one another except during collisions.
Real gas particles, however, have a finite size, and they can attract one another. These differences become particularly important when a gas is compressed to high pressures or cooled towards the point where it condenses into a liquid. Under such conditions, the ideal gas law may no longer accurately describe what happens.
Van der Waals developed a more sophisticated equation that accounts for both the space occupied by molecules and the attractive forces between them. His work helped explain why real substances depart from ideal gas behaviour and how gases and liquids are related.
The significance extends beyond a single equation. Scientists need models that simplify reality enough to be useful while still capturing the important features of the system being studied. The ideal gas law remains valuable in many situations, while the van der Waals equation can offer a better description under conditions where molecular size and attraction matter more.
Bring this into the classroom
Van der Waals provides an excellent starting point for teaching gases, particle theory, pressure and the limitations of scientific models. Ask students to compare the assumptions behind an ideal gas with what they know about actual particles. Do molecules really have no volume? Can they attract one another? When might these details become important?
A useful discussion question is: Why do real gases behave differently from the ideal-gas model?
Students could also compare predictions from a simple model with observations or data for a real gas. Older learners studying equations can explore how changing temperature, pressure and volume affects gas behaviour, while younger students can use particle diagrams to explain why gases compress more easily than liquids and solids.
This story also helps students see that an imperfect model is not necessarily a bad model. The ideal gas law is useful because it works well in many circumstances. The scientific challenge is recognising when a model's assumptions matter and when a more detailed explanation is needed.
November 23, 1887: Henry Moseley and the evidence behind the periodic table
Henry Gwyn Jeffreys Moseley was born on November 23, 1887. His experiments with X-rays helped establish atomic number as the correct basis for ordering the elements in the periodic table. His work built on the discoveries of earlier scientists and helped resolve problems that could not be fully explained by arranging elements according to atomic mass alone.
When Dmitri Mendeleev developed his periodic table in the nineteenth century, he arranged the known elements largely by atomic mass and recurring chemical properties. His table was remarkably successful, and he even left gaps for elements that had not yet been discovered. However, some elements appeared in an order that did not fit neatly with their atomic masses.
Moseley's work helped explain why. In experiments conducted in 1913, he directed X-rays at samples of different elements and measured the X-rays produced. The frequencies of these X-rays followed a clear mathematical pattern related to each element's atomic number.
Atomic number is the number of protons in an atom's nucleus. It defines which element an atom is. For example, every carbon atom has six protons, while every oxygen atom has eight. If the number of protons changes, the atom becomes a different element.
Moseley's measurements provided experimental evidence that atomic number was more fundamental than atomic mass for arranging the elements. The discovery helped resolve anomalies in the periodic table and strengthened the connection between the table's order and atomic structure. The Royal Society of Chemistry's history of the periodic table explains how Moseley's experiments helped establish this modern arrangement.
This is a powerful example of how scientific instruments can reveal patterns that are difficult to detect by observation alone. X-rays allowed Moseley to investigate properties of atoms indirectly, turning a theoretical idea about atomic number into something that could be measured.
Bring this into the classroom
This event works particularly well when teaching the periodic table, atomic structure, elements or the nature of scientific evidence.
Ask students why a table arranged by atomic mass might appear to work for most elements but fail for a few. What could scientists do when the accepted arrangement produces exceptions? Moseley's work gives students an example of using new measurements to test an existing system rather than simply forcing the evidence to fit.
A useful question is: How did atomic number improve the periodic table?
Students can compare atomic number and relative atomic mass for selected elements, looking for examples where the order by mass does not match the order by proton number. They can then explain why atomic number is the defining property of an element, while isotopes of the same element can have different numbers of neutrons and different masses.
For older students, Moseley's work also opens up discussion about spectroscopy, X-ray radiation and the relationship between experimental measurements and mathematical patterns. It is a reminder that a table used in classrooms around the world was refined through a series of scientific investigations, not simply invented in its final form.
November 23, 1889: An early coin-operated phonograph changes how people hear music
On November 23, 1889, a coin-operated phonograph installed at a San Francisco saloon offered customers the opportunity to listen to recorded music by inserting a coin. It is often described as an early jukebox, although claims about it being the absolute first should be treated cautiously. The Smithsonian Magazine's history of the jukebox describes how this type of machine helped bring recorded music into public spaces.
The technology depended on an earlier breakthrough: the phonograph developed by Thomas Edison in 1877. Edison's machine could record sound and play it back. Sound entering a mouthpiece caused a diaphragm and attached stylus to vibrate, leaving a physical pattern on a rotating recording surface. During playback, the stylus followed that pattern, making the diaphragm vibrate and reproducing sound.
Early recordings were far from the digital audio students know today. The first phonographs used materials such as tinfoil, which wore out quickly. Later machines used improved recording media, including wax cylinders. The Smithsonian National Museum of American History's phonograph collection provides an explanation of how the recording and playback mechanism worked.
Coin-operated phonographs added a new way for people to access this technology. Customers could pay to listen without owning a machine or buying a recording themselves. Early systems were simple compared with modern jukeboxes, and listeners often used listening tubes because sound amplification was limited. Nevertheless, the idea helped establish a new way of sharing recorded music in public places.
The broader story is about how an invention can change society through new ways of using it. Recording sound made it possible to replay a performance, while coin-operated machines made recorded entertainment available to people in everyday settings. Later developments in records, radio, cassette tapes, CDs and digital streaming continued to change how people access music.
Bring this into the classroom
This event is a useful way to connect sound waves, vibrations, energy transfer, materials and engineering. Ask students how a machine could store information about a sound wave and then reproduce it later. What would the recording need to preserve for a voice or musical instrument to sound recognisable?
Students could draw a simple diagram of a phonograph, identifying the diaphragm, stylus, rotating cylinder and sound vibrations. They could then compare the process with a modern microphone, digital audio file and loudspeaker. Which parts of the process are similar, and which have changed?
A useful discussion question is: How do new ways of distributing sound change music listening?
For an extension, students could create a timeline of sound recording technology and consider how each development changed access to music. They might compare the cost and convenience of a public phonograph with owning a record player or using a streaming service today.
This is also an opportunity to discuss the difference between invention and impact. A technology can exist before it becomes widely useful. Improvements in recording materials, manufacturing, distribution and affordability all helped recorded sound become part of everyday life.
A fourth November 23 story: reusable rocket technology
The calendar also highlights a major milestone in space engineering. In November 2015, Blue Origin's New Shepard vehicle reached space and returned its booster to a vertical landing. Reusing a rocket stage could reduce the need to build an entirely new booster for every launch, although refurbishment, testing and operational costs still matter. Blue Origin describes the achievement in its New Shepard mission announcement.
This is a useful example of how engineering involves more than making something work once. A reusable launch system must manage energy, heat, forces, guidance and landing accuracy while being designed for further flights. Ask students: Why could reusing a rocket stage change the economics of spaceflight?
Using Science on This Day as a classroom activity
The three main stories from November 23 can be used as short lesson starters, retrieval prompts, reading tasks or discussion activities. Van der Waals connects particle theory with the limits of mathematical models. Moseley shows how evidence can improve the periodic table. The coin-operated phonograph links sound physics to the development of technology and entertainment.
A simple approach is to present one event and ask students to explain its scientific significance in their own words. They might identify a key concept, describe the evidence that supported a discovery, or propose a question they would investigate next. This encourages them to connect curriculum knowledge with the people, instruments and problems that shaped science.
My November Science on This Day activity set includes 109 STEM stories across the month in several classroom-friendly formats: interactive HTML, editable Google Slides, a filterable spreadsheet and a PDF version. The collection is designed to help teachers choose events by date or subject and use discussion questions to support classroom conversations.
If you would like to explore other ready-to-use science materials, you can browse the The Teaching Astrophysicist store for free and paid resources across physics, chemistry, biology, Earth science and space.
What else happened in science history?
November 24 offers several strong links to the themes of evidence and scientific explanation. In 1639, astronomers Jeremiah Horrocks and William Crabtree made the first known successful observations of a transit of Venus, an event that later helped astronomers develop methods for estimating distances in the Solar System. In 1859, Charles Darwin's On the Origin of Species was published, presenting an influential explanation of how natural selection can shape biological diversity. On the same date in 1974, the fossil known as Lucy was discovered in Ethiopia, becoming an important source of evidence in the study of human evolution. Apollo 12 also splashed down in the Pacific on November 24, 1969, returning lunar samples for scientific investigation.
On November 25, the Great Storm of 1703 offers a case study in historical weather records and the difficulties of estimating the strength of past storms. The date also marks the birth of Julius Robert von Mayer, an early contributor to the principle of conservation of energy, and Albert Einstein's presentation of the final field equations of general relativity in 1915.
These events connect meteorology, energy transfer and the physics of gravity.
As November comes to a close, the December Science on This Day activity set offers 132 STEM stories across all 31 days of December, with multiple formats to support classroom use. It is designed for teachers who want a ready-to-use event to introduce a topic, prompt discussion or build connections across the curriculum.
The stories of van der Waals, Moseley and the early phonograph show that scientific progress takes many forms. Sometimes it means improving an equation. Sometimes it means using a new instrument to find a hidden pattern. And sometimes it means applying scientific understanding to create technology that changes everyday life. November 23 is a reminder that science is not just a collection of facts: it is a continuing process of testing ideas, refining explanations and finding new ways to understand the world.
Thanks for reading
Cheers and stay curious
Oliver - The Teaching Astrophysicist
