![]() The mole does more than represent a big number: It provides a key link for converting between the number (amount) of a substance, and its mass. Instead of being used for things we encounter in daily life, the mole is used by scientists when talking about enormous numbers of particles like atoms, molecules, and electrons-although the mole’s usefulness goes beyond being a helpful scientific term. Obviously, the mole is not a term we need for most things in daily life. Metallic character decreases from left to right in each period of the periodic table.Figure 1: An Eastern Gray Squirrel. Metallic character increases down a group. Going down a group, the atomic radius increases: the outer electrons are farther from the nucleus and are easier to remove, thus increasing the metallic character.The metallic character is essentially the ease with which an atom gives up an electron Metalloid: an element with properties intermediate between metals and nonmetals. Metalloids divide the periodic table in a zigzag line between metals on the left and nonmetals on the right.Nonmetal: poor conductor of heat and electricity. They are generally softer elements, often colored, with lower melting and boiling points than most metals.Metal: good conductor of heat and electricity. They tend to be hard, metallic-looking solids with high melting and boiling points. The majority of elements are metals.Most elements can be classified as metals or nonmetals based on their ability to conduct heat and electricity: ⇒ very stable elements, generally considered to be inert gases Noble gases: last column = helium, neon, argon, (krypton, xenon, radon).⇒ colorful and corrosive nonmetals, very reactive Halogens: penultimate column = fluorine, chlorine, bromine, iodine, (astatine).⇒ react with O 2, less reactive to water than alkali metals ![]() Alkaline-earth metals: 2 nd column = beryllium, magnesium, calcium, (strontium, barium, radium).⇒ very reactive metals and can explode if they are exposed to water ![]()
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