Showing posts with label element. Show all posts
Showing posts with label element. Show all posts

March 13 - Happy Birthday, Joseph Priestly

  Posted on March 13, 2022 

This is an update of my post published on March 13, 2011:



Breathe deep! With each breath, your lungs “discover” oxygen!

Animals need oxygen to burn food and gain energy. It is plants who put the oxygen we need into the air; plants separate oxygen atoms from hydrogen atoms during photosynthesis (in other words, they split water into its component parts) and then release the oxygen as a waste gas.

This means that animals are dependent on plants for both food and oxygen. This is why plants must vastly outnumber animals on the planet.



But just because we need oxygen doesn't mean that we know much about it. Look around you—sniff the air—notice that oxygen is odorless, tasteless, colorless, and invisible—just like nitrogen and carbon dioxide and many other gases!


Scientists and naturalists “discovered” oxygen when they were able to separate it out from other odorless, invisible gases in the atmosphere. The guy that we usually give credit for this discovery, Joseph Priestly, was born on this day in 1733.


Priestly did a lot of experiments and tried to separate out different “airs.” In one of those experiments, he did manage to isolate oxygen—but he didn't know that he had done that per se. He thought he had removed from air an invisible fluid named phlogiston, which (he thought) caused heating and burning.



Priestly called his discovery "dephlogisticated air." He published his findings so that other scientists could copy his apparatus and experiments and compare their results.


That part—publishing his work in specific detail so that others could replicate it—is very good. It is what happens in science—and it is the reason that Priestly gets credit for discovering something he didn't know he'd discovered. (Two scientists, Antoine Lavoisier and Carl Wilhelm Scheele, also isolated oxygen but were either slower to do so or slower to publish—so they don't usually get the credit.)

What isn't so good for Priestly's reputation is that he held onto an incorrect theory even when evidence came to light that pointed in another direction. The whole phlogiston theory was wrong, but Priestly was determined to defend it and fought against the oxygen theory of combustion.


By the way, Priestly also invented soda water and wrote a history of electricity. You might think that, with all this scientific discovery and invention, he would be always be referred to as a scientist. But although he contributed to science, Priestly is often called a theologian (one who studies religion), a cleric (a person in a religious order), a “natural philosopher,” and/or a teacher.





 
 


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August 27 - Discovery of Gallium!!

Posted on August 27, 2021


This is an update of my post published on August 27, 2010:


Gallium doesn't exist by itself in nature, so it took some doing to find it!

Dmitri Mendeleev predicted its existence, using the periodic table of elements: There was zinc (Zn) with atomic number 30, and arsenic (As) with atomic number 33... So, Mendeleev asked, where were the elements with the atomic numbers 31 and 32?

The beauty of Mendeleev's periodic table is that elements share properties with the elements positioned above them on the table. So Mendeleev was able to guess some of the properties of the elements before they had even been discovered.

After 15 years of work, on this date in 1875, Paul Emile Lecoq de Boisaudran discovered the predicted element with atomic number 31. He named the new element gallium in honor of his country, France (Gallia).


Gallium is right under aluminum on the periodic table, and like aluminum it is a soft, silvery metal.




Lecoq made his discovery with a spectroscope, which uses a prism to separate the various colors of light from a light source. When chemists use spectroscopes, they either burn a bit of material and analyze the light emitted from the burning material, or they create a gas form of the material and shine white light through the gas and see which light is absorbed.

In this case, Lecoq was analyzing zinc blende, and he found two violet lines that were not accounted for by other elements in the ore. Later the same year, Lecoq was able to isolate gallium using a process called electrolysis.


Gallium has a very low melting point.
Like, if you try to hold it in your hand, it melts!


Create a spectrum.

In other words, make a rainbow! 

Use a glass prism to separate white light into a rainbow. Yep, a rainbow is a spectrum! Remember, each raindrop acts as a prism separating the light.



If you don't have a prism, check out this YouTube video of a prism creating a rainbow.

Or make a rainbow in some other way - there are lots!



To make a rainbow with a hose, make sure the sun isn't overhead
and stand so that the sun is at your back. Then shoot the hose
toward your shadow - making sure that your thumb or a nozzle
makes the stream of water into a spray of many drops of water.


A glass of water can make a rainbow!


CDs can make rainbows!


Here is a video about a man called the Rainbow Maker.


 



















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January 11 - Anniversary of the Discovery of Francium

 Posted on January 11, 2021

This post is an update of my January 11, 2010, post:

The element francium was discovered by French chemist Marguerite Catherine Perey on this date in 1939. She had been analyzing another element, actinium, which experiences radioactive decay. In other words, without any outside force, actinium suddenly releases radiation or a particle—and becomes another element! Perey's sample of actinium became astatine, bismuth, and then francium.




Francium, too, is radioactive and experiences this kind of spontaneous decay, becoming astatine, radium, or radon. Radioactive elements are dangerous because of the radiation and high-energy particles they release.
 

Each radioactive element has its own half-life, which is a measure of how soon it decays into another element. (Half-life means, as you might guess, that half of a given sample has decayed in the time period.) Some radioactive elements have long half-lives. Uranium 234, for example, has a half-life of 240,000 years. But Francium is very unstable, with a half-life of only 22 minutes.

As a matter of fact, francium is the most unstable of all the elements that occurs in nature. Scientists estimate that there is no more than one ounce of francium in all of the earth's crust at one time. That makes it the second rarest naturally-occurring element!

Since Perey discovered the element, she got to name it. Francium was her second suggestion and honors France as the place of discovery.
(Her first suggestion was catium, because Perey believed this new discovery would be the most electrically positive ion - or cation - of all the elements. Her supervisor didn't like the name suggestion and pointed out that people would think of cat rather than cation.)

Last to be discovered...now on to creating new elements!

Perey's discovery of francium was the last discovery of a naturally-occuring element. But scientists have created (or synthesized) other elements in nuclear reactors and particle colliders. (A few of these elements have actually been discovered in tiny amounts, in nature, after first being synthesized.)

Some of these elements have been named after the place in which they were created, following Perey's example of naming her discovery after her country. So many of the elements were first created in America, scientists started to run out of place names. Look at this list:
Americium – created in 1944, at the University of Chicago, U.S. of America 
Berkelium – created in 1949, at the University of California, Berkeley, USA
Californium – created in 1950, at the University of California, Berkeley, USA
Lawrencium – created in 1961, at the University of California, Berkeley, USA, in the Lawrence Radiation Lab

Other elements were named after famous scientists (although not the scientists who created them!). Who is each of these elements named for?
1. Curium
2. Einsteinium
3. Fermium
4. Mendelevium
5. Nobelium


ANSWERS: 
1. Marie and Pierre Curie 
2. Albert Einstein 
3. Enrico Fermi 
4. Dimitri Mendeleev
5. Alfred Nobel


You can explore the periodic table of elements here.

Here is a game that can help you learn the Atomic Symbols of each element.

This visual periodic table is beautiful, with pictures and videos and lots of info (click around, of course!).

Now, for some common stuff...

Francium is a heavy, unstable, extremely rare element. But all around us are lighter, stable, common elements. Can you match the element name with the description?

1. Carbon
2. Oxygen
3. Helium
4. Nitrogen
5. Gold
6. Hydrogen
7. Chlorine
8. Aluminum

A. Atomic number 1 – the simplest, lightest, most common element in the universe

B. Atomic number 2 – used inside lighter-than-air toys, it's safe because it doesn't react to other elements

C. Atomic number 6 – the building block of life because it forms chains and rings easily

D. Atomic number 7 – most of the air we breathe is made of this

E. Atomic number 8 – something plants get rid of, but that animals (and also fires!) need

F. Atomic number 13 – a lightweight, silvery metal

G. Atomic number 17 – a poisonous gas that, when mixed with a particular poisonous metal, makes yummy salt!

H. Atomic number 79 – a heavy yellow metal

ANSWERS: 
1.C 
2.E 
3.B 
4.D 
5.H 
6.A 
7.G 
8.F








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