The discoveries of gallium (1875) and germanium (1886) provided great support for Mendeleev’s work. But Mendeleev went one step further than Meyer: He used his table to predict the existence of elements that would have the properties similar to aluminum and silicon, but were yet unknown. Both published tables with the elements arranged according to increasing atomic mass. Fluorine (F), chlorine (Cl), bromine (Br), and iodine (I) also exhibit similar properties to each other, but these properties are drastically different from those of any of the elements above.ĭimitri Mendeleev in Russia (1869) and Lothar Meyer in Germany (1870) independently recognized that there was a periodic relationship among the properties of the elements known at that time. For example: Li, Na, and K are much more reactive than are Ca, Sr, and Ba Li, Na, and K form compounds with oxygen in a ratio of two of their atoms to one oxygen atom, whereas Ca, Sr, and Ba form compounds with one of their atoms to one oxygen atom. However, the specific properties of these two groupings are notably different from each other. A second grouping includes calcium (Ca), strontium (Sr), and barium (Ba), which also are shiny, good conductors of heat and electricity, and have chemical properties in common. One such grouping includes lithium (Li), sodium (Na), and potassium (K): These elements all are shiny, conduct heat and electricity well, and have similar chemical properties. Identify metals, nonmetals, and metalloids by their properties and/or location on the periodic tableĪs early chemists worked to purify ores and discovered more elements, they realized that various elements could be grouped together by their similar chemical behaviors.Predict the general properties of elements based on their location within the periodic table.State the periodic law and explain the organization of elements in the periodic table.Alkali metals are not the type of metals you would use for coins or houses.By the end of this section, you will be able to: They are malleable (bendable) and sometimes soft enough to be cut with a dull knife. Their light weight and physical properties separate them from other metals. You will find that the alkali group is shiny and light in weight. Often, in chemistry, characteristics are assigned by the way elements look. In fact, when you put some of these pure elements in water (H 2O), they can cause huge explosions. An increased desire to bond means you are more reactive. When you are that close to having a full shell, you want to bond with other elements and lose that electron. That's one electron away from being happy (full shells). Why? They all have one electrons in their outer shell. As with all families, these elements share traits. Now that we've covered that exception, the members of the family include: lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs) and francium (Fr). While hydrogen sits in Group I, it is NOT an alkali metal. Hydrogen is a very special element of the periodic table and doesn't belong to any family. When we told you about families, we said that they were groups of elements that react in similar ways. Who's in the family? Starting at the top we find hydrogen (H). The "one" in this case refers to having one electron in the outermost orbital. When we talk about the groups of the periodic table, scientists use Roman numerals when they write them out. That far left column is Group One (Group I). They are a very different family, even though they have a similar name. You should remember that there is a separate group called the alkaline earth metals in Group Two. They are also known as the alkaline metals. When looking for families, the first one you will find is the alkali metal family of elements. Let's go to the left side of the periodic table.
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