1 00:00:00,280 --> 00:00:02,000 Speaker 1: This Day in History Class. It's a production of I 2 00:00:02,080 --> 00:00:07,120 Speaker 1: Heart Radio. Hey y'all, I'm Eves and you're listening to 3 00:00:07,200 --> 00:00:10,440 Speaker 1: This Day in History Class, a podcast for people interested 4 00:00:10,520 --> 00:00:16,240 Speaker 1: in the big and small moments in history. Today's March six. 5 00:00:25,320 --> 00:00:29,600 Speaker 1: The day was March six, eight sixty nine. Russian chemist 6 00:00:29,680 --> 00:00:34,880 Speaker 1: Dmitri Mendeleev presented the first periodic table. The periodic table 7 00:00:35,000 --> 00:00:37,760 Speaker 1: is an arrangement of the chemical elements, ordered based on 8 00:00:37,800 --> 00:00:42,440 Speaker 1: their properties. People have known about the elements such as copper, silver, 9 00:00:42,560 --> 00:00:47,120 Speaker 1: and mercury since ancient times, but modern discoveries of elements 10 00:00:47,159 --> 00:00:51,200 Speaker 1: began to ramp up in the eighteenth century. Scientists began 11 00:00:51,280 --> 00:00:57,200 Speaker 1: identifying elements such as hydrogen, oxygen, and titanium, but communication 12 00:00:57,360 --> 00:01:01,520 Speaker 1: and labeling regarding these elements was not to form That said. 13 00:01:01,800 --> 00:01:06,080 Speaker 1: Scientists were beginning to recognize relationships between the elements by 14 00:01:06,080 --> 00:01:11,200 Speaker 1: the early nineteenth century. In eighteen seventeen, German chemists Johann 15 00:01:11,400 --> 00:01:15,240 Speaker 1: duber Einer noticed that the atomic weight of strontium fell 16 00:01:15,480 --> 00:01:19,600 Speaker 1: midway between the weights of calcium and barium. Atomic weight 17 00:01:19,680 --> 00:01:23,080 Speaker 1: is the mass of one atom of an element. Just 18 00:01:23,200 --> 00:01:26,680 Speaker 1: over a decade later, he realized that other triads existed 19 00:01:27,040 --> 00:01:30,839 Speaker 1: such as the halogen triad of chlorine, bromine, and iodine. 20 00:01:31,959 --> 00:01:36,000 Speaker 1: Other scientists later added to this existing knowledge, showing more 21 00:01:36,080 --> 00:01:41,600 Speaker 1: relationships among elements. In eighteen sixty two, French geologist A. E. B. 22 00:01:42,000 --> 00:01:46,720 Speaker 1: Deschancretois proposed a classification of the elements. He put a 23 00:01:46,800 --> 00:01:49,960 Speaker 1: list of the elements on a cylinder ordered by atomic weight. 24 00:01:50,320 --> 00:01:54,320 Speaker 1: The resulting curve allowed closely related elements to line up vertically. 25 00:01:55,360 --> 00:01:59,280 Speaker 1: Deschancretoise suggested that quote, the properties of the elements are 26 00:01:59,280 --> 00:02:03,240 Speaker 1: the properties of numbers, but his chart also contained ions 27 00:02:03,280 --> 00:02:08,480 Speaker 1: and compounds. English chemist John Newlands also classified the elements 28 00:02:08,520 --> 00:02:11,720 Speaker 1: in a table based on their physical properties. Around this time, 29 00:02:12,840 --> 00:02:17,160 Speaker 1: Dmitri Mendeleev was a chemistry professor at the University of St. Petersburg. 30 00:02:17,440 --> 00:02:20,840 Speaker 1: He also wrote chemistry textbooks. As he was writing the 31 00:02:20,880 --> 00:02:24,800 Speaker 1: textbook The Principles of Chemistry, he began comparing the properties 32 00:02:24,840 --> 00:02:28,480 Speaker 1: of groups of elements. The patterns that he noticed led 33 00:02:28,560 --> 00:02:31,240 Speaker 1: him to use the order of atomic weights to arrange 34 00:02:31,280 --> 00:02:35,760 Speaker 1: the elements in groups. Mendeleev proposed the periodic law, by 35 00:02:35,760 --> 00:02:39,200 Speaker 1: which quote, the elements arranged according to the magnitude of 36 00:02:39,240 --> 00:02:44,440 Speaker 1: atomic weights show a periodic change of properties. On March six, 37 00:02:44,639 --> 00:02:48,440 Speaker 1: eighteen sixty nine, Mendeleev's periodic table was presented to the 38 00:02:48,520 --> 00:02:52,160 Speaker 1: Russian Chemical Society. Elements in the table were arranged in 39 00:02:52,240 --> 00:02:56,560 Speaker 1: periods or rows, as well as groups or columns. He 40 00:02:56,639 --> 00:03:00,160 Speaker 1: described elements according to both atomic weight also known as 41 00:03:00,160 --> 00:03:03,640 Speaker 1: a relative atomic mass, and valance, or the ability of 42 00:03:03,639 --> 00:03:08,120 Speaker 1: an atom to combine or interact with another atom. Mendeleev 43 00:03:08,200 --> 00:03:11,360 Speaker 1: even left space for elements that had not been discovered yet, 44 00:03:11,720 --> 00:03:14,400 Speaker 1: saying that there were missing elements with atomic weights between 45 00:03:14,520 --> 00:03:19,200 Speaker 1: sixty five and seventy five. Just months after Mendeleev's periodic 46 00:03:19,240 --> 00:03:23,799 Speaker 1: table was published, German chemists Lotar Mayer published a similar table, 47 00:03:24,160 --> 00:03:27,079 Speaker 1: though Mendeleev receives much of the credit for his creation, 48 00:03:28,280 --> 00:03:31,680 Speaker 1: In the eighteen seventies and eighteen eighties, elements that Mendeleev 49 00:03:31,760 --> 00:03:37,040 Speaker 1: had predicted were discovered, namely gallium, scandium, and germanium, that 50 00:03:37,120 --> 00:03:41,680 Speaker 1: gave more credence to his periodic table. Altogether, he predicted 51 00:03:41,720 --> 00:03:45,960 Speaker 1: ten elements, eight of which turned out to exist. Mende 52 00:03:46,000 --> 00:03:48,360 Speaker 1: Love was recognized for his work before he died in 53 00:03:48,440 --> 00:03:51,680 Speaker 1: nineteen o seven. Today, there are one hundred and eighteen 54 00:03:51,720 --> 00:03:55,560 Speaker 1: elements on the Periodic Table. I'm Eve Chef Code and 55 00:03:55,560 --> 00:03:58,200 Speaker 1: hopefully you know a little more about history today than 56 00:03:58,280 --> 00:04:01,480 Speaker 1: you did yesterday. If you'd like to follow us on 57 00:04:01,600 --> 00:04:04,840 Speaker 1: social media, you can do so at T D i 58 00:04:05,200 --> 00:04:11,240 Speaker 1: h C Podcast on Instagram, Twitter, and Facebook. Our email 59 00:04:11,240 --> 00:04:15,960 Speaker 1: address is this day at I heart media dot com. 60 00:04:15,960 --> 00:04:18,480 Speaker 1: Thanks for tuning in, and we'll see you again tomorrow. 61 00:04:33,000 --> 00:04:35,320 Speaker 1: For more podcasts from I Heart Radio, visit the iHeart 62 00:04:35,400 --> 00:04:37,839 Speaker 1: Radio app, Apple Podcasts, or wherever you listen to your 63 00:04:37,839 --> 00:04:38,520 Speaker 1: favorite shows.