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Every account of the periodic table names Mendeleev. Fewer students learn that a German chemist, Lothar Meyer, reached a very similar table at almost the same time, and showed periodicity in a way Mendeleev did not: as a graph. This post covers who Meyer was, what his atomic volume curve shows, how to calculate points on it yourself, and what his careful style can teach you.
Who was Lothar Meyer?
Gisela Boeck's biographical study of Meyer in Substantia (2019) records that Julius Lothar Meyer was born in Varel, Germany, on 19 August 1830. He trained in medicine like his father, then worked with Robert Bunsen in Heidelberg on the gases in blood, and studied mathematical physics in Königsberg. He attended the first international chemistry congress at Karlsruhe in 1860, where Cannizzaro's case for Avogadro's ideas struck both Meyer and Mendeleev.
His textbook *Die modernen Theorien der Chemie* appeared in 1864. He was professor at the Karlsruhe Polytechnikum from 1868 to 1875 and at Tübingen from 1876. Boeck notes that he and Mendeleev received the Davy Medal together on 2 November 1882. He was elected rector of the University of Tübingen for 1894 to 1895 and died on 11 April 1895.
What did Meyer's early tables show?
The 1864 book already grouped elements by valency, with near-constant differences in atomic weight between members of a group. Boeck points out that Meyer placed tellurium before iodine although its atomic weight was higher, marked doubtful weights with question marks, and left a gap after silicon. He even worked out that the missing element should have an atomic weight near 73, but he did not describe its properties, as Mendeleev later did for eka-silicon. Our post on how Mendeleev predicted gallium, scandium and germanium tells that side of the story.
A fuller table drafted in 1868 was left with his successor at Eberswalde and was published only in 1895. The current NCERT Class 11 chemistry unit on periodicity puts it simply: by 1868 Meyer had a table closely resembling the modern one, but it was published after Mendeleev's work.
What is the atomic volume curve?
In his 1870 paper, Boeck explains, Meyer calculated atomic volume as atomic weight divided by the density of the element as a solid. Plotted against atomic weight, the values rise and fall in waves. He wrote that similar properties recur after an increase in atomic weight of first 16 units, then 46, and finally 88 to 92. Boeck notes the graph shows periodicity more strikingly than the tables do, and that Meyer later started his tables with the alkali metals because they show the largest atomic volume in each row.
NCERT says that Meyer plotted atomic volume, melting point and boiling point against atomic weight, and that, unlike Newlands, he noticed the repeating pattern changes length. That is the same thing as the 16, 46, 88 progression: the periods get longer.
Worked example: rebuild part of the curve
Atomic volume = molar mass ÷ density, in cm³ mol⁻¹. Here are modern values from the Royal Society of Chemistry's element pages for sodium, magnesium, aluminium and silicon:
Sodium: 22.990 ÷ 0.97 = 23.7 cm³ mol⁻¹
Magnesium: 24.305 ÷ 1.74 = 14.0 cm³ mol⁻¹
Aluminium: 26.982 ÷ 2.70 = 10.0 cm³ mol⁻¹
Silicon: 28.085 ÷ 2.3296 = 12.1 cm³ mol⁻¹
Across period 3 the volume falls sharply from sodium, then levels off. Now take the alkali metals, lithium, sodium, potassium and rubidium:
Lithium: 6.94 ÷ 0.534 = 13.0
Sodium: 23.7 (from above)
Potassium: 39.098 ÷ 0.89 = 43.9
Rubidium: 85.468 ÷ 1.53 = 55.9
Each alkali metal sits on a peak, and the peaks get higher down the group. That is Meyer's curve in miniature.
Common mistakes to avoid:
Dividing the wrong way. Divide molar mass by density. The other way round gives mol per cm³, and the peaks turn into dips.
Treating atomic volume as atomic size. It also depends on how atoms pack in the solid, so use it to see the trend, not to rank radii precisely.
Forgetting the modern basis. Meyer plotted against atomic weight. Today's table is ordered by atomic number, which is why tellurium and iodine no longer look out of place.
If the ideas behind these trends, such as effective nuclear charge, still feel shaky, the Fermi Concept Library covers every concept in physics, chemistry, biology, mathematics and computing, one idea at a time.
How did Meyer differ from Mendeleev?
Boeck's assessment is balanced. Meyer used atomic weights to one or two decimal places, left out elements whose weights he did not trust, and placed most elements in the right order. Mendeleev ordered all known elements, with more mistakes, but boldly predicted new elements and their properties. In 1870 Meyer wrote that his table was "in the main identical with that of Mendelejeff", a phrase that fed a long priority dispute. An English translation of the 1870 paper appears in Boeck and Rocke's 2022 collection of Meyer's classic texts.
What can a student learn from Meyer?
Plot your data. A pattern that hides in a list of numbers can jump out of a graph.
Care about data quality. Meyer spent years redetermining atomic weights with Karl Seubert because bad numbers produce false patterns.
Be honest about what you cannot explain. Meyer said plainly that the cause of periodicity was not yet known.
Try it now: calculate the atomic volume of calcium and strontium from the RSC data and check that they fall just after the potassium and rubidium peaks.
