Cesium or Caesium is a relatively soft metal with a color similar to gold.
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At First Glance
When you look at the periodic table, some things are instantly apparent about the element cesium. For example, the atomic number, the atomic weight, and the atomic symbol are in the element key. Cs, or Cesium, has 55 protons which you know from the atomic number. The mass of an atom is the number of protons plus the number of neutrons, and the atomic mass is the average of all the masses of an element and its isotopes. Isotopes are all the different kinds of cesium, some having more neutrons than another, therefore having a different mass. The atomic mass of cesium is 132.91.
Using the periodic table, you can find things out about cesium, or any element, that are not explicitly written. The atomic mass, number, and symbol are written out for you, but if you look a bit harder you can tell the element classification, period number, group number, and the number of neutrons. The element classification tells a lot about a particular element and is easy to find. On any periodic table, there is a zig-zag line on the right side of it. On some periodic tables this is red, on others it is bolded black, but no matter how it is distinguished, it makes a very important characteristic of any element known. Those elements to the left of the line, like cesium, are metals while those to the right are non-metals. Once you know that cesium is a metal, you can draw many conclusions about how it behaves under certain circumstances. The period number and group number are fairly self-explanatory, but knowing how to find these can tell you things about the atom that would not be otherwise easy to figure out. The periods, or horizontal rows, tell you how many energy levels your element has. Since cesium is in the sixth row from the top, it has six energy levels. The groups, or families, are similar too. The groups, or vertical columns, are labeled one to eighteen from left to right. Families are the same idea but are a little different. Families are the eight tall columns that are labeled one to eight from left to right. The family number tells you the number of electrons in the valence, or outermost, energy level. Cesium is in the first family, so it has one valence electron. Finding the number of neutrons is a bit different from finding the family number, group number, and element classification. For those three things, you were looking at something on the periodic table and stating what you saw, but for the number of neutrons, it is not written anywhere on the periodic table at all. But with a little reasoning, the number of neutrons shouldn’t be hard to find. Using the atomic mass of 132.91 and the atomic number of 55, the number of neutrons is easy to spot. What is the atomic mass? The sum of the number of protons and neutrons. The atomic number tells you the number of protons, 55, and the atomic mass tells you the number of protons plus the number of neutrons - so to find the number of neutrons, subtract the atomic number from the atomic mass and round to the nearest whole number. The number of neutrons in cesium is 78.
Summary:
Atomic Symbol: Cs
Atomic Number: 55
Atomic Mass: 132.91
Element Classification: metal
Family: IA (Alkali Metals)
Group Number: 6
Number of Neutrons: 78
Sky Blue
Caesius, the Latin word for sky blue, is where cesium gets its name. The two German scientists who discovered cesium in 1860 named it after the blue lines found in its spectrum. On average, only two ounces of cesium are found in a ton (2000 pounds) of earth - it’s quite rare. Even when you find cesium in the crust of Earth, it is not pure cesium. Like all Alkali metals, cesium is very reactive and is never found un-bonded in nature.
Cesium In The World
What Time Is It?
Keeping track of time is essential to almost everything we do, but how do we know whose time is right? My watch may be a few minutes faster than yours, so how do we know whether we are a few minutes early, or almost late? Scientists keep an extremely accurate clock called atomic clocks. These clocks keep the time and only get off a second about every 20 million years. The most precise atomic clocks use cesium. The second is the base unit of measuring time, and as we know, is a small portion of time. Because of the level of accuracy of these cesium clocks, scientists define a second by cesium vibrations. Every time the cesium-133 atom vibrates 9.129,631,770 times, exactly one second has passed.
Blast Off
In the 20th century, cesium became involved in the engines for spacecraft. Ion drives are a type of engine that work differently and are more efficient than other engines. Normal engines burn fuel which produces hot gas that shoots out the back of the spacecraft. This pushes the rocket off the ground and helps it climb higher into the sky. Ion drives have high-speed electrons bombard the atoms in the fuel and take some of the electrons away from them. The atoms become positively charged because they lost some negatively charged electrons. These ions, or positively charged atoms, shoot out the back of the engine similar to the hot gas in the original engine. Unlike the original engine, ion drives remain close to the spacecraft for longer. They make the rocket gradually get faster until it is going extremely fast. The first ion engines used cesium and in 1974, a cesium ion engine was successfully used on a satellite in space. However, now ion engines use Xenon, an unreactive gas, instead of cesium.
Oops
In 1987, a Brazilian city became contaminated with radiative cesium-137. Some men broke into an old hospital when they were looking for scrap metal. They took apart a machine hoping to find some parts to sell when they came across some white powder. This powder was really radioactive cesium chloride that glowed blue in the dark. These men passed it around to their friends and families to look at. The people thought it was harmless until some people began to fall ill. Eventually, four people died and some houses got contaminated and had to be torn down.
Go Getter
Cesium is known as a getter when it is used in bulbs and evacuated tubes. In order to operate properly, a bulb must be free of all gasses. Because cesium is so reactive, if a small amount is put in a bulb, it will react with the air forming a solid cesium compound. The reason that cesium is called a getter is because it gets the gasses out of a bulb causing the bulb to work properly.
But Wait, There's More...
Cs-134 and Cs-137 are the two radioactive isotopes of cesium. These variants of just regular Cs, became well known after their release in 1945-1963. They were set free into the atmosphere during the above-ground nuclear testing and during the Chernobyl disaster. When the power plant in Ukraine, Chernobyl, released Cs-137, it affected many animals as it was drained into the ground and consumed by plants. Cs-137 has a life of about 60 years which was devastating for the Ukrainians at the time of the accident. Large amounts of Cs-137 were also set free in 2011 from the Japanese power plant that was damaged in the tsunami.
Compounds
Some compounds with cesium include Cesium Hydroxide Solution (CsOH), Cesium Sulfate (Cs2SO4), Cesium Trifluoroacetate (CF3COOCs), Cesium Carbonate (Cs2CO3), and Cesium Iodide (CsI), Cesium Chloride (CsCl). While the first three are water solutions, the final three are white crystal.
