The Alkali Metals
These elements are all soft, silvery metals. The alkali metals are all very reactive and they increase in reactivity as you move down the group. This means the most reactive alkali metals have to be stored in protective vials, filled with either oil or a noble gas such as argon. The alkali metals make up Group 1 in the periodic table. All alkali metals have one electron in their outer electron shells. While hydrogen is also in Group 1 in the periodic table, it is not classified as an alkali metal. This is because hydrogen is categorized as a nonmetal instead. Hydrogen is a gas at room temperature, and it does not share any properties with the alkali metals, other than its reactivity. Hydrogen is in a group of its own. |
Lithium is the lightest of the alkali metals, and the lightest of all metals, with only 3 protons in its nucleus. As a result, it has an atomic number of 3. Lithium also has an atomic mass of approximately 6.941. It is so soft that you could cut it with a knife. Lithium is very reactive, but it is the least reactive alkali metal.
Lithium was discovered in 1817 by Johan August Arfvedson. Arfvedson had discovered the presence of a previously unknown element while he was examining petalite ore. Petalite is one of the most common ores of lithium. The other two main ores are lepidolite and spodumene.
This element is very useful in everyday life, even though it is highly reactive. Lithium and aluminum are combined to form an alloy that is very useful for constructing airplanes. And of course, there are the lithium batteries.
Lithium was discovered in 1817 by Johan August Arfvedson. Arfvedson had discovered the presence of a previously unknown element while he was examining petalite ore. Petalite is one of the most common ores of lithium. The other two main ores are lepidolite and spodumene.
This element is very useful in everyday life, even though it is highly reactive. Lithium and aluminum are combined to form an alloy that is very useful for constructing airplanes. And of course, there are the lithium batteries.
Sodium is crucial to the existence of life on Earth, being an ingredient in salt (sodium chloride, chemical formula NaCl). There are 11 protons in the nucleus of every sodium atom, therefore sodium has an atomic number of 11. The atomic mass of sodium is approximately 22.990. Sodium is more reactive than lithium, but its reactivity is hardly anything compared to the other alkali metals like cesium and francium.
Sodium was discovered in 1807 by the British chemist Sir Humphrey Davy. He isolated the pure metal by running an electric current through sodium hydroxide, which is a compound of sodium, hydrogen, and oxygen. This method is called electrolysis.
Compounds of sodium are very important in the production of glass, soap, and paper. Sodium hydroxide can be used to clear out a clogged drain, and it is also a very important substance in chemistry.
Sodium was discovered in 1807 by the British chemist Sir Humphrey Davy. He isolated the pure metal by running an electric current through sodium hydroxide, which is a compound of sodium, hydrogen, and oxygen. This method is called electrolysis.
Compounds of sodium are very important in the production of glass, soap, and paper. Sodium hydroxide can be used to clear out a clogged drain, and it is also a very important substance in chemistry.
Potassium is more reactive than sodium and far more reactive than lithium. The reason for this is that potassium is farther down the alkali metal group, and the farther down you go, the more reactive the elements get. Like sodium, potassium is essential to life on Earth. It has an atomic number of 19, and an atomic mass of approximately 39.0983.
Also like sodium, potassium was discovered in 1807 by Sir Humphrey Davy. Potassium was actually isolated before sodium, and it was the first metal that was isolated by electrolysis.
The largest use of potassium is in fertilizers. In fact, 95 percent of all the potassium produced goes toward making fertilizers. Plants, like humans, are dependent on potassium, and many types of soil did not have much potassium in them.
Foods that are good sources of potassium include apricots, broccoli, cantaloupe, and of course, bananas.
Also like sodium, potassium was discovered in 1807 by Sir Humphrey Davy. Potassium was actually isolated before sodium, and it was the first metal that was isolated by electrolysis.
The largest use of potassium is in fertilizers. In fact, 95 percent of all the potassium produced goes toward making fertilizers. Plants, like humans, are dependent on potassium, and many types of soil did not have much potassium in them.
Foods that are good sources of potassium include apricots, broccoli, cantaloupe, and of course, bananas.
Rubidium is so reactive that if one broke open a vial of it, the rubidium would rapidly catch fire. It has an atomic number of 37 (therefore, there are 37 protons in the nucleus of every atom of rubidium) and it has an atomic mass of approximately 84.468. Rubidium is not known to be essential to life, but it can be absorbed by both plants and humans because it imitates potassium (rubidium and potassium are very similar to each other).
Rubidium was first isolated by Robert Bunsen in 1861. Unlike sodium and potassium, rubidium was discovered not by electrolysis, but by spectroscopy. In spectroscopy, a sample of the element is heated, and this gives a characteristic spectrum of lines. Bunsen found some dark red lines in the spectrum and named his new discovery rubidium, after the Latin word rubidius, or "deepest red". Rubidium is used in atomic clocks, the most accurate clocks, along with cesium.
Rubidium was first isolated by Robert Bunsen in 1861. Unlike sodium and potassium, rubidium was discovered not by electrolysis, but by spectroscopy. In spectroscopy, a sample of the element is heated, and this gives a characteristic spectrum of lines. Bunsen found some dark red lines in the spectrum and named his new discovery rubidium, after the Latin word rubidius, or "deepest red". Rubidium is used in atomic clocks, the most accurate clocks, along with cesium.
Cesium is one of the most reactive elements on the periodic table. If you put a piece of cesium into a bowl of water, the cesium will explode. It must be kept in oil and handled in an unreactive atmosphere to avoid it reacting with the air. Cesium has an atomic number of 55 and an atomic mass of approximately 132.905.
Like rubidium, cesium was discovered by Robert Bunsen, using spectroscopy, but cesium was discovered a year earlier, in 1860. Bunsen found two blue lines in the resulting spectrum and, realizing that he had found a new element, he named it cesium, from the Latin caesius, or "sky blue" because of those two blue lines in cesium's spectrum.
Also like rubidium, cesium is used in atomic clocks, the most accurate known clocks. Cesium clocks are more accurate then rubidium ones. Cesium atomic clocks are very accurate (1 second in 300,000 years!).
Like rubidium, cesium was discovered by Robert Bunsen, using spectroscopy, but cesium was discovered a year earlier, in 1860. Bunsen found two blue lines in the resulting spectrum and, realizing that he had found a new element, he named it cesium, from the Latin caesius, or "sky blue" because of those two blue lines in cesium's spectrum.
Also like rubidium, cesium is used in atomic clocks, the most accurate known clocks. Cesium clocks are more accurate then rubidium ones. Cesium atomic clocks are very accurate (1 second in 300,000 years!).
Francium is even more reactive then cesium is. No one has combined francium with water, given the fact that francium is very radioactive and has a short half-life, and also because the resulting explosion would be massive. Francium has an atomic number of 87 and an atomic mass of 223.020.
Francium was discovered in 1939 by Marguerite Perey. She discovered it after analyzing a sample of the radioactive metal actinium.
This element has absolutely no applications other than research purposes, for a couple of reasons. Francium is one of the rarest elements in the periodic table, and as mentioned earlier, it is highly radioactive, with a very short half-life. The isotope with the longest half-life is francium-223 (223 being the total number of protons and neutrons), and this has a half-life of only 22 minutes.
Francium was discovered in 1939 by Marguerite Perey. She discovered it after analyzing a sample of the radioactive metal actinium.
This element has absolutely no applications other than research purposes, for a couple of reasons. Francium is one of the rarest elements in the periodic table, and as mentioned earlier, it is highly radioactive, with a very short half-life. The isotope with the longest half-life is francium-223 (223 being the total number of protons and neutrons), and this has a half-life of only 22 minutes.