![]() (credit a: modification of work by Serge Lachinov credit b: modification of work by “Den fjättrade ankan”/Wikimedia Commons) (a) Dimitri Mendeleev is widely credited with creating (b) the first periodic table of the elements. ![]() Although Mendeleev and Meyer had a long dispute over priority, Mendeleev’s contributions to the development of the periodic table are now more widely recognized (Figure 1).įigure 1. 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.So it's gonna have to electrons, So its electron configuration is just gonna be five s two. So we know we're going to start in the five s orbital and then we again we just count its place in the row one too. Why don't we do strong Thiam? So again we look at the road number strong. So it's got three electrons in that Balin shelf and it's in group three A. Now we go up and look at aluminum's group number. Most show now, the S orbital can only hold two electrons, so it's gonna be three s to three p one. Just gonna have three electrons in its outer. Now, how many electrons is aluminum having its outer shell? Well, basically, we just count its position in the row. Of all of our shows are out of those shelves, they're gonna be level three. So that means we're going to be on the third level. So living, um, you can see is in the third row. So let's write out the electron configuration for aluminum. In the last group on the periodic table, group ate a These are noble gases. Accept our noble gases and the noble gases are the elements located here. All right, so basically, this is going to be everything. So just to review really quickly, a representative element is an element that has a partially filled outer shelf. Now, for representative elements, the number of valence electrons oven element is equal to its group number. And when we say groups on the periodic table, those are columns of the periodic tables like this. Okay, so these are gonna be very, very outside electrons. Electrons are the electrons located in the outer most show of an L MC. ![]() So first, let's talk about what? Our valence electrons. Today we're gonna be talking about feelings, electrons and how they kind of relate to an element group number.
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