At which meeting in 1860 did chemists agree on better atomic weights?Answer: The Karlsruhe Congress. Source: Royal Society of Chemistry, Development of the periodic table; Science History Institute, Julius Lothar Meyer and Dmitri Ivanovich Mendeleev; Wikipedia, History of the periodic table. Read 2026-10-01.
Before atomic number was known, by what did chemists put the elements in order?Answer: Atomic weight. Source: Royal Society of Chemistry, Development of the periodic table; Western Oregon University, A Brief History of the Development of the Periodic Table; Wikipedia, History of the periodic table. Read 2026-10-01.
Béguyer de Chancourtois made the first periodic arrangement of the elements. What was his job?Answer: Geologist. Source: Royal Society of Chemistry, Development of the periodic table; Western Oregon University, A Brief History of the Development of the Periodic Table; Wikipedia, History of the periodic table. Read 2026-10-01.
Chlorine, bromine and iodine form a triad. What did Döbereiner notice about bromine, the middle one?Answer: Its atomic weight is close to the average of the other two. Source: Western Oregon University, A Brief History of the Development of the Periodic Table; Wikipedia, History of the periodic table. Read 2026-10-01.
Show all 55 questions (51 more)
Before Mendeleev, continued
How did other chemists first treat Newlands's table?Answer: They made fun of it. Source: Royal Society of Chemistry, Development of the periodic table; Wikipedia, History of the periodic table. Read 2026-10-01.
In which year did Döbereiner set out his triads?Answer: 1829. Source: Royal Society of Chemistry, Development of the periodic table; Western Oregon University, A Brief History of the Development of the Periodic Table; Wikipedia, History of the periodic table. Read 2026-10-01.
Lothar Meyer drew a well-known graph in 1870. What did he plot against atomic weight?Answer: Atomic volume. Source: Royal Society of Chemistry, Development of the periodic table; Science History Institute, Julius Lothar Meyer and Dmitri Ivanovich Mendeleev. Read 2026-10-01.
Lothar Meyer's first table was printed in 1864. How many elements did it hold?Answer: 28. Source: Royal Society of Chemistry, Development of the periodic table; Science History Institute, Julius Lothar Meyer and Dmitri Ivanovich Mendeleev. Read 2026-10-01.
Newlands compared the pattern in his table of elements to what?Answer: The notes of a musical scale. Source: Royal Society of Chemistry, Development of the periodic table; Western Oregon University, A Brief History of the Development of the Periodic Table; Wikipedia, History of the periodic table. Read 2026-10-01.
What did Johann Döbereiner call his groups of three similar elements?Answer: Triads. Source: Royal Society of Chemistry, Development of the periodic table; Western Oregon University, A Brief History of the Development of the Periodic Table; Wikipedia, History of the periodic table. Read 2026-10-01.
What did John Newlands call his rule that elements repeat like notes in music?Answer: The law of octaves. Source: Royal Society of Chemistry, Development of the periodic table; Western Oregon University, A Brief History of the Development of the Periodic Table; Wikipedia, History of the periodic table. Read 2026-10-01.
What did Newlands's table lack that Mendeleev's table had?Answer: Gaps for elements not yet discovered. Source: Royal Society of Chemistry, Development of the periodic table; Wikipedia, History of the periodic table. Read 2026-10-01.
What was the telluric screw of 1862?Answer: A spiral of the elements drawn around a cylinder. Source: Royal Society of Chemistry, Development of the periodic table; Western Oregon University, A Brief History of the Development of the Periodic Table; Wikipedia, History of the periodic table. Read 2026-10-01.
Which French chemist printed a list of the elements in his textbook of 1789?Answer: Antoine Lavoisier. Source: Royal Society of Chemistry, Development of the periodic table; Science History Institute, Antoine-Laurent Lavoisier; Wikipedia, History of the periodic table. Read 2026-10-01.
Which three elements make up one of Döbereiner's triads?Answer: Lithium, sodium and potassium. Source: Royal Society of Chemistry, Development of the periodic table; Western Oregon University, A Brief History of the Development of the Periodic Table; Wikipedia, History of the periodic table. Read 2026-10-01.
Who made the telluric screw?Answer: Alexandre-Émile Béguyer de Chancourtois. Source: Royal Society of Chemistry, Development of the periodic table; Western Oregon University, A Brief History of the Development of the Periodic Table; Wikipedia, History of the periodic table. Read 2026-10-01.
Mendeleev's table 15
About how many elements were known when Mendeleev made his table?Answer: A little over 60. Source: Western Oregon University, A Brief History of the Development of the Periodic Table; Science History Institute, Julius Lothar Meyer and Dmitri Ivanovich Mendeleev. Read 2026-10-01.
By atomic weight, iodine should come before tellurium. Why did Mendeleev put iodine after it?Answer: Iodine behaves like chlorine and bromine, so it belongs in their group. Source: Royal Society of Chemistry, Development of the periodic table; Wikipedia, History of the periodic table. Read 2026-10-01.
Did Mendeleev ever win a Nobel Prize?Answer: No. Source: Royal Society of Chemistry, Development of the periodic table; Western Oregon University, A Brief History of the Development of the Periodic Table. Read 2026-10-01.
How did Mendeleev order the elements in his table of 1869?Answer: By atomic weight. Source: Royal Society of Chemistry, Development of the periodic table; Western Oregon University, A Brief History of the Development of the Periodic Table. Read 2026-10-01.
How did Mendeleev try out different arrangements of the elements?Answer: He wrote each element on a card and moved the cards around. Source: Royal Society of Chemistry, Development of the periodic table; Western Oregon University, A Brief History of the Development of the Periodic Table; Wikipedia, History of the periodic table. Read 2026-10-01.
In which year did Dmitri Mendeleev publish his periodic table?Answer: 1869. Source: Royal Society of Chemistry, Development of the periodic table; Western Oregon University, A Brief History of the Development of the Periodic Table; Science History Institute, Julius Lothar Meyer and Dmitri Ivanovich Mendeleev. Read 2026-10-01.
Mendeleev predicted an element he called eka-aluminum. It was found in 1875. What is it called?Answer: Gallium. Source: Royal Society of Chemistry, Development of the periodic table; Western Oregon University, A Brief History of the Development of the Periodic Table; Wikipedia, History of the periodic table. Read 2026-10-01.
What did the discovery of gallium, scandium and germanium show?Answer: That Mendeleev's predictions were right. Source: Royal Society of Chemistry, Development of the periodic table; Western Oregon University, A Brief History of the Development of the Periodic Table. Read 2026-10-01.
What was Mendeleev writing when he worked out his table?Answer: A chemistry textbook. Source: Royal Society of Chemistry, Development of the periodic table; Western Oregon University, A Brief History of the Development of the Periodic Table; Science History Institute, Julius Lothar Meyer and Dmitri Ivanovich Mendeleev. Read 2026-10-01.
Where was Mendeleev born?Answer: Tobolsk, in Siberia. Source: Royal Society of Chemistry, Development of the periodic table; Western Oregon University, A Brief History of the Development of the Periodic Table; Science History Institute, Julius Lothar Meyer and Dmitri Ivanovich Mendeleev. Read 2026-10-01.
Which element did Mendeleev predict under the name eka-boron?Answer: Scandium. Source: Western Oregon University, A Brief History of the Development of the Periodic Table; Wikipedia, History of the periodic table. Read 2026-10-01.
Which element did Mendeleev predict under the name eka-silicon?Answer: Germanium. Source: Western Oregon University, A Brief History of the Development of the Periodic Table; Wikipedia, History of the periodic table. Read 2026-10-01.
Which of Mendeleev's three predicted elements was found first?Answer: Gallium. Source: Royal Society of Chemistry, Development of the periodic table; Wikipedia, History of the periodic table. Read 2026-10-01.
Who published a very similar table in 1870, a year after Mendeleev?Answer: Lothar Meyer. Source: Royal Society of Chemistry, Development of the periodic table; Western Oregon University, A Brief History of the Development of the Periodic Table; Science History Institute, Julius Lothar Meyer and Dmitri Ivanovich Mendeleev. Read 2026-10-01.
Why did Mendeleev leave gaps in his table?Answer: For elements that had not been discovered yet. Source: Royal Society of Chemistry, Development of the periodic table; Western Oregon University, A Brief History of the Development of the Periodic Table. Read 2026-10-01.
The modern table 14
Argon has a greater atomic weight than potassium, yet it comes first in the table. Why?Answer: Argon has the smaller atomic number. Source: Western Oregon University, A Brief History of the Development of the Periodic Table; Royal Society of Chemistry, Development of the periodic table. Read 2026-10-01.
By what is the modern periodic table ordered?Answer: Atomic number. Source: Royal Society of Chemistry, Development of the periodic table; Western Oregon University, A Brief History of the Development of the Periodic Table. Read 2026-10-01.
How is the periodic law stated today?Answer: The properties of the elements repeat with atomic number. Source: Western Oregon University, A Brief History of the Development of the Periodic Table; Royal Society of Chemistry, Development of the periodic table. Read 2026-10-01.
In which year did Seaborg share the Nobel Prize in Chemistry?Answer: 1951. Source: Western Oregon University, A Brief History of the Development of the Periodic Table; Science History Institute, Glenn Theodore Seaborg. Read 2026-10-01.
What did Moseley use to measure atomic number?Answer: X-rays. Source: Royal Society of Chemistry, Development of the periodic table; Western Oregon University, A Brief History of the Development of the Periodic Table; Wikipedia, History of the periodic table. Read 2026-10-01.
What does an element's atomic number count?Answer: The protons in the nucleus of its atom. Source: Royal Society of Chemistry, Development of the periodic table; Wikipedia, History of the periodic table. Read 2026-10-01.
Where did the noble gases go in the periodic table?Answer: In a new group of their own. Source: Royal Society of Chemistry, Development of the periodic table; Science History Institute, William Ramsay; Western Oregon University, A Brief History of the Development of the Periodic Table. Read 2026-10-01.
Which element did Glenn Seaborg and his team discover in 1940?Answer: Plutonium. Source: Western Oregon University, A Brief History of the Development of the Periodic Table; Science History Institute, Glenn Theodore Seaborg. Read 2026-10-01.
Which element is named after Glenn Seaborg?Answer: Seaborgium. Source: Western Oregon University, A Brief History of the Development of the Periodic Table; Wikipedia, History of the periodic table. Read 2026-10-01.
Which noble gas did William Ramsay and Lord Rayleigh find first, in air?Answer: Argon. Source: Science History Institute, William Ramsay; Wikipedia, History of the periodic table; Western Oregon University, A Brief History of the Development of the Periodic Table. Read 2026-10-01.
Who first proposed that the charge on the nucleus sets an element's place in the table?Answer: Antonius van den Broek. Source: Western Oregon University, A Brief History of the Development of the Periodic Table; Wikipedia, History of the periodic table. Read 2026-10-01.
Who gave the actinides a row of their own under the lanthanides?Answer: Glenn Seaborg. Source: Western Oregon University, A Brief History of the Development of the Periodic Table; Science History Institute, Glenn Theodore Seaborg; Wikipedia, History of the periodic table. Read 2026-10-01.
Whose work in 1913 showed that the elements belong in order of atomic number?Answer: Henry Moseley. Source: Royal Society of Chemistry, Development of the periodic table; Western Oregon University, A Brief History of the Development of the Periodic Table. Read 2026-10-01.
Whose work on the noble gases added a new group to the periodic table?Answer: William Ramsay. Source: Royal Society of Chemistry, Development of the periodic table; Science History Institute, William Ramsay. Read 2026-10-01.
Who did what, and when 10
How long after Mendeleev's table of 1869 was gallium found?Answer: Six years. Source: Royal Society of Chemistry, Development of the periodic table; Wikipedia, History of the periodic table. Read 2026-10-01.
How many years passed between Mendeleev's table and Moseley's work on atomic number?Answer: 44. Source: Royal Society of Chemistry, Development of the periodic table; Western Oregon University, A Brief History of the Development of the Periodic Table. Read 2026-10-01.
Put these in order of time, earliest first.Answer: Lavoisier's list, Döbereiner's triads, the telluric screw, Mendeleev's table. Source: Royal Society of Chemistry, Development of the periodic table; Wikipedia, History of the periodic table. Read 2026-10-01.
Which group of elements was unknown when Mendeleev made his table?Answer: The noble gases. Source: Royal Society of Chemistry, Development of the periodic table; Western Oregon University, A Brief History of the Development of the Periodic Table. Read 2026-10-01.
Which list is in the right order, earliest first?Answer: Triads, law of octaves, Mendeleev's table, atomic number. Source: Royal Society of Chemistry, Development of the periodic table; Western Oregon University, A Brief History of the Development of the Periodic Table. Read 2026-10-01.
Which of these came first?Answer: Mendeleev's table. Source: Royal Society of Chemistry, Development of the periodic table; Western Oregon University, A Brief History of the Development of the Periodic Table. Read 2026-10-01.
Which of these came last?Answer: Seaborg's actinide row. Source: Western Oregon University, A Brief History of the Development of the Periodic Table; Wikipedia, History of the periodic table. Read 2026-10-01.
Which of these pairs matches a scientist with his work?Answer: Henry Moseley: atomic number from X-rays. Source: Royal Society of Chemistry, Development of the periodic table; Western Oregon University, A Brief History of the Development of the Periodic Table. Read 2026-10-01.
Which pairing of a scientist and an idea is right?Answer: John Newlands: the law of octaves. Source: Royal Society of Chemistry, Development of the periodic table; Western Oregon University, A Brief History of the Development of the Periodic Table. Read 2026-10-01.
Which scientist is matched with the right idea?Answer: Dmitri Mendeleev: gaps for undiscovered elements. Source: Royal Society of Chemistry, Development of the periodic table; Western Oregon University, A Brief History of the Development of the Periodic Table. Read 2026-10-01.
This history of the periodic table quiz asks who did what, and when: the triads of 1829, the law of octaves, Mendeleev's table of 1869 with its gaps, Moseley's atomic numbers and the changes made since.
Read the full guide
Four sets
Before Mendeleev covers Lavoisier, Döbereiner, de Chancourtois, Newlands and Meyer. Mendeleev's table asks about 1869, the gaps and the three predicted elements. The modern table runs from the noble gases to Seaborg. The last set puts people and events in order.
Pick an answer
Press a choice and it is marked at once, with a one-line reason and the places it was checked. A round is ten questions; a set picked from the Start from menu plays whole. Exam mode asks 20.
As a worksheet
After a round, print a 20-question worksheet with its answer key, or the whole set. See all with answers opens the full list.
Three names to keep apart: Döbereiner found triads, Newlands octaves, and Meyer a table much like Mendeleev's.
Questions and answers
Who made the first periodic table?
Dmitri Mendeleev published the table that today's is built on in 1869. Before him, Béguyer de Chancourtois wound the elements around a cylinder in 1862, and John Newlands and Lothar Meyer drew tables of their own.
Which elements did Mendeleev predict?
He described three before they were found: eka-aluminum, eka-boron and eka-silicon. They are gallium, found in 1875, then scandium, and germanium, found in 1886.
Why is the periodic table ordered by atomic number, not atomic weight?
Henry Moseley's X-ray measurements of 1913 showed that atomic number gives the true order. It explains pairs such as tellurium and iodine, which sit out of order by weight.
Who added the noble gases to the periodic table?
William Ramsay. He and Lord Rayleigh found argon in air in the 1890s, and Ramsay went on to helium, neon, krypton and xenon, which formed a new group.