User: Why are elements within a group similar in chemical and physical properties?

Weegy: By "group" people usually mean the vertical columns in the periodic table. The similarities are caused by the fact that all the elements in the group having the same number of electrons in their outer shell - this is what determines the chemical [ properties of an element, meaning that is what determines how the element will bond to other atoms. In the structure of atoms, electrons are located in "shells" that contain a certain number of spots available to hold electrons. As atomic number increases in the periodic table (as the number of protons in the nucleus increases), electrons are added into first the inner lower energy shells, but as these shells fill up, electrons are added to the next higher energy level shell until it is filled up, and so on. Chemical properties are determined by how many electrons are located in the outer energy shell of the atom. As I recall, as you move down a column in the periodic table, the element's outer electrons are in electron shells of increasing energy level, but they have the same number of electrons in those shells. That number determines the chemical behavior of the element, so that they all behave similarly. I hope this helps. http://answers.yahoo.com/question/?qid=20081023155714AAxxdeV ]
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