![]() ![]() These colors are produced as electrons jump from their home environment orbiting the nucleus and returning back again. Burning lithium produces a vivid crimson red color sodium a yellow one potassium lilac rubidium red and cesium violet. The pyrotechnic industry loves these Group I elements for their vibrant colors and explosive nature. patent on July 31, 1790, for soap under the new patent statute just signed into law by President George Washington a few months earlier. People have known since antiquity that wood ashes produce a potassium salt which, when combined with animal fat, will yield soap. The New Testament refers to it 10 times and calls sodium carbonate “neter” and potassium nitrate “saltpeter.” For instance, the Old Testament mentions salt – a combination of the alkali metal sodium with chlorine – 31 times. Some alkali metals have been known and put to good use long before Mendeleev created the periodic table. Subsequent discovery of these new elements proved his prediction correct.įireworks owe their vivid colors to the Group I metals. After arranging all of the then known elements, Mendeleev took the bold step of leaving blanks where his extrapolation of chemical properties showed that an element should exist. It is called periodic because every eighth element repeats the properties of the one above it in the table. Using chemical properties as his guide, Russian chemist Dimitri Mendeleev correctly ordered the first Group I elements into his 1869 periodic table. In spite of these trends, the properties of the elements of Group I are more similar to each other than those of any other group. Of all the Group I elements, cesium has the largest volumes because the outermost single electron is loosely held. Because it is highly radioactive, virtually no chemistry is performed with this element.īecause each element in this column has a single outer electron in a new shell, the volumes of these elements are large and increase dramatically when moving from the top to the bottom of the group. ![]() Lithium is at the top of the group and is followed by sodium, Na potassium, K rubidium, Rb cesium, Cs and ends with the radioactive francium, Fr. gstraub/Īs its name implies, Group I elements occupy the first column in the periodic table. The outermost electron surrounding the Cesium atom is far from the nucleus and thus easy to remove. The melting point of the elements within a group also decreases from the top to the bottom of a group. The force required to remove the outermost electron, known as the ionization potential, also increases from the left-hand side of the table, which has elements with a metallic character, to the right side, which are nonmetals.Įlectronegativity decreases from the top of the column to the bottom. For the same reason electronegativity – the degree to which an element tends to gain electrons – increases from left to right. More protons means that electrons are pulled in more tightly toward the nucleus. Moving from the left side of the period to the right, the atomic radius becomes smaller because each element has one additional proton and one additional electron. The horizontal rows of the table are called periods. This is important because how elements interact and react with each other depends on their ability to lose and gain electrons to make new compounds. But the amount of energy needed to rip off an outer electron decreases going from the top to the bottom because the electrons are farther from the nucleus and not held as tightly. Going from the top of Group I to the bottom, for example, the atomic radii – the distance from the nucleus to the outer electrons – increases. And the properties can be assumed based on the location within the group. ![]() Elements in the same group share similar properties. By studying the behavior and trends of Group I elements, we can get a glimpse of how the periodic table is arranged and how to interpret it.Įach of the 18 columns in the table is called a group or a family. I am a chemist who spent his career building new molecules, sometimes using Group I elements. Not only are they very reactive, they are soft and shiny, can easily be cut even with a dull knife and are the most metallic of all known elements. For further dramatic effect, I also placed some potassium into water and astonished everyone with the explosive bluish flames.īecause Group I metals, also known as alkali metals, are very reactive, like the sodium from the rail car or the potassium, they are not found in nature in pure form but only as salts. While on the air I added some sodium to a bit of water in a petri dish and we observed the vicious reaction. A television reporter called me for an explanation of why firefighters were not allowed to use water on the flames bursting from the mangled car. The news broke that a railroad car, loaded with pure sodium, had just derailed and was spilling its contents. ![]()
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