23 October 25

October 23, or 10-23, is always Mole Day! It celebrates the number 6.02 times 10 to the 23rd power, which is known as Avogadro’s Number. In chemistry it counts the number of atoms or molecules in “one mole” of a substance, equal to the atomic weight or molecular weight in grams. One mole of copper weighs 63.5 grams, which is about 22 pennies (minted before 1982). One mole of water weighs 18 grams, which is a little more than one tablespoon.

My tie for today celebrates the periodic table of elements. Hidden inside my shirt, a T shirt celebrates Mole Day, with a cartoon mole and the words “Proud to be a Chemist”! On the back of the T shirt you can read a long list of all the chemical elements and compounds in the human body!

23 October 23 (10-23)

 Every year on 23 October, chemists around the world celebrate Mole Day. It's an amusing association of 10-23 with the exponential part of Avogadro's Number, 6.022x10**23. This number counts the number of items in one mole of a substance. The mole is the most useful measurement unit for comparing different substances. Eighteen milliliters of water (slightly more than 3 and a half teaspoons) contains the same number of molecules of water as there are atoms in 56 grams of iron (two big nails or 56 paper clips). My tie shows many boxes from the periodic table, where the atomic weight (at the bottom of each box) reports the mass of one mole of that element. In my ethics class on Mole Day, I showed examples of moles of water, alcohol, iron, carbon, aluminum, table salt and sugar.

8 February 23

I'm wearing my periodic table tie to celebrate both yesterday's status as Periodic Table Day and today's birthday anniversary for Dmitri Mendeleev (1834-1907). Periodic Table Day recognizes the work of English chemist John Newlands, who published the earliest known table of the elements on 7 February 1863. Six years later, Mendeleev produced a slightly different format that expanded the table into the one we recognize today. In the photo I'm holding our household periodic table display, which is a transparent block holding real samples of many of the elements!

7-8 February 22

Dmitri Mendeleev, the "father" of the modern periodic table of the elements, was born in Russia on 8 February 1839. So I'm wearing my periodic table tie for him. Yesterday, 7 February, is sometimes celebrated as Periodic Table Day, marking the 1863 publication of one of the first tables of elements, by English chemist John Newlands. Mendeleev released his table six years later, apparently unaware of what Newlands had produced. Both of them expressed the general pattern that the elements, when arranged in order of their atomic weights, show remarkable similarities if you pair them by eights (the first one and the eighth one, and the second one and ninth one, and so on). Although our periodic table today has many more elements than either Newlands or Mendeleev knew, its design still shows the close resemblances of sodium-and-potassium and carbon-and-silicon and oxygen-and-sulfur and so on (the vertical "groups").

20 August 21

Today's periodic table tie celebrates the work of John Newlands in 1863-1864. "On February 7, 1863, English chemist John Newlands published one of the first table of elements, which divided the known 56 elements into 11 groups based on the “Law of Octaves.” This suggested that any one element will have similar properties to elements eight places before and behind it on the table." (National Day Calendar). Newlands published more about this on 20 August 1864. (OUPblog) About four years later, Dmitri Mendeleev independently produced what became the modern periodic table.

23 October 20

 It's Mole Day! It's a special day for chemists worldwide, celebrated annually on October 23 (10-23), because those digits are the most important part of Avogadro's Number, 6.02 x 10²³. Yes, that's an absolutely huge, unfathomable number. It counts the number of "things" in a mole of a substance, such as the number of molecules in 18 grams of water, the number of molecules in 342 grams of sugar, and the number of atoms of iron in two large nails (56 grams). The mole concept is at the foundation of stoichiometry (the part of chemistry that shows how many atoms are in a molecule and how those atoms get rearranged during chemical reactions). To get one mole of water molecules you need two moles of hydrogen atoms and one mole of oxygen atoms, but since elemental oxygen exists as O₂, and elemental hydrogen exists as H₂,  the reaction is ordinarily shown as combining one mole of hydrogen (molecules) with one-half mole of oxygen (molecules) to produce one mole of water (molecules).

The periodic table (like the one on my tie) shows the "atomic weight" of each of the elements, which is the measure in grams for 6.02 x 10²³ atoms (one mole) of each one.

23 October 19

Happy National Chemistry Week! And especially, Happy Mole Day! October 23, 10-23, is always of special interest to chemists because of its association with the exponential part of Avogadro's Number (6.02 x 10²³). That is the number of "things" in one mole of any substance, such as the number of water molecules in 18 grams of water (3-1/2 teaspoons) or the number of iron atoms in 56 grams of nails or paper clips. Moles measure the "combining ratios" of chemicals. This year (2019) has also been designated the International Year of the Periodic Table of the Elements, and it is also the centenary for IUPAC, the International Union of Pure and Applied Chemistry. That is the worldwide organization that sets the rules for chemical nomenclature (how chemical compounds are named) and also maintains the official Periodic Table of the Elements!

23 October 18

October 23 (10 - 23) is always a great day to be a chemist. We celebrate "Mole Day" today because 10 - 23 represents the exponential part of Avogadro's Number (6.02 times 10 to the 23rd power), one of the most important fundamental constants in chemistry. It counts the number of things in ONE MOLE of a substance. (The word came from the German use of "Mol" as a unit for counting molecules. It has nothing to do with the small animal, although cute pictures of moles show up in Mole Day decorations and T-shirts.) A little pile of 12 grams of carbon, for example, has that many atoms of carbon, and a few teaspoons (18 milliliters) of water has that many molecules of H-2-O. If you gather 56 ordinary paper clips, you have 6.02-times-ten-to-the-23rd-power atoms of iron. If you ever took a chemistry class, you undoubtedly ran into calculations using the "Ideal Gas equation," PV = nRT, where "n" is the number of moles. My periodic table tie shows the symbols, atomic numbers and atomic weights for many elements. (The atomic weight for an element equals one mole of it.)

23 October 17

Happy Mole Day! Chemists around the world celebrate Mole Day on October 23 (10-23) because those digits match the exponential part of Avogadro's Number, 6.02 X 10²³. Some people arise at 6:02 a.m. on this day for special significance. On the Periodic Table, the atomic weights stand for the number of grams of each element that contain one mole of those atoms. The mole unit is fundamental in chemistry because it counts the number of items (atoms, ions, molecules, etc.) that exist in one formula weight of that substance. In the photo I am holding one mole of each substance: 56 grams of iron (nails), 342 grams of sucrose (crystals), 27 grams of aluminum (foil), and 18 grams of water (colored blue). Not shown directly in the photo is one mole of air (measured at 29 grams/mole), occupying 22.4 liters = about 6 gallons, at normal temperatures and pressures.

23 October 16

Happy Mole Day! Chemists around the world celebrate Mole Day on October 23 (10-23) because those digits match the exponential part of Avogadro's Number, 6.02 X 10²³. Some people arise at 6:02 a.m. on this day for special significance. On the Periodic Table, the atomic weights stand for the number of grams of each element that contain one mole of those atoms. The mole unit is fundamental in chemistry because it counts the number of items (atoms, ions, molecules, etc.) that exist in one formula weight of that substance. For example, I am holding 58 grams (roughly 2 ounces) of table salt, which contains one mole of sodium atoms and one mole of chlorine atoms. That's the same number of water molecules that exist in 18 grams of water (a little more than one tablespoon). Measuring moles is essential in understanding chemical reactions. Added note: This is also Mother-In-Law's Day, which I celebrated in several ways with Wilma Wollenweber!

7 February 16

Happy (Earliest) Periodic Table Day! "On February 7, 1863, English chemist John Newlands published one of the first table of elements, which divided the known 56 elements into 11 groups based on the 'Law of Octaves.' This suggested that any one element will have similar properties to elements eight places before and behind it on the table." (Source -- National Day Calendar.) This was six years before Dmitri Mendeleev published his more systematic table which became the foundation for what we use today.

20 April 15

113 years ago today, Marie and Pierre Curie obtained their first purified samples of radium. Their discoveries formed the basis for understanding the decay of uranium, thorium and other elements.

23 October 14

The two nails I'm holding, weighing 56 grams (2 ounces), contain about 602,000,000,000,000,000,000,000 atoms of iron. Today chemists worldwide celebrate Mole Day, to honor 10 to the 23rd power, from "Avogadro's Number," 6.02 X 10²³. That is the number of atoms in one mole, or "combining weight," of an element. Eighteen grams of water -- a little more than one tablespoon -- contain 2 moles of hydrogen atoms and one mole of oxygen atoms. Ask your local chemist for more information! And please have a REALLY HUGE CELEBRATION for Mole Day!

26 August 13

Happy Birthday, Antoine Lavoisier! The chemist who is credited with discovering oxygen (in 1778) was born on this date in 1743. Joseph Priestley had worked with the same gas, calling it "dephlogisticated air," but Lavoisier knew that he had isolated a pure substance that was essential for combustion, and he named it oxygen.

22 October 12

Happy National Chemistry Week! It's celebrated every October, during the week that includes October 23 (for reasons to be explained tomorrow).

8 February 12

Today marks the birthday of Dmitri Mendeleev (1834-1907), who developed the first versions of what we know and love as the Periodic Table of the Elements. His table organized what was known about the weights and "combining properties" of the elements known around 1869, and accurately predicted the properties of several elements not yet discovered.

7 November 11

The chemical elements curium (Cm, #96) and meitnerium (Mt, #109) are named for two great scientists born on November 7: Marie Curie, in 1867, and Lise Meitner, in 1878. They were both pioneers in studying radioactivity and nuclear fission.

04 February 11

Today is Friday which is usually an un-tied (though not untidy) day for me. But I want to honor my dear friend Harry Smiley, who died Wednesday and whose visitation is this evening. Harry's primary occupation was as a chemistry teacher, and so I am wearing one of my periodic table ties. I knew Harry better as a philosophic and theological skeptic with strong spiritual foundations. My Facebook status today says that "he was thoroughly convinced that God's grace was all that we could ever depend on, and all that we ever needed."

12 September 10

September 12 marks the 1897 birthday of Irène Joliot-Curie, daughter of Pierre and Marie Curie. She received the Nobel Prize in Chemistry in 1935 for her research in nuclear chemistry, at that time termed "artificial radioactivity." She worked extensively with polonium and other elements discovered by her parents, designing methods by which atoms of one element could be "transmuted" into another element (e.g., boron --> nitrogen).

09 February 10

Yesterday marked the 1834 birthday of Dmitri Mendeleev, originator of the periodic table of elements. (Today is my sister Gloria's birthday, too. Next year I'll remember to let her choose my tie for this day.)