![]() ![]() Fluorine (F, 9) is the most reactive of all and can even form compounds with noble gases. The halogens are all very reactive, because they have seven electrons in their outer shell and desperately need eight.Like the boron group, the chalcogens are generally moderately reactive, but have variable properties.The pnictogens' properties vary widely as well.Properties of the carbon group elements vary widely. ![]() ![]() As you go down the column, the likelihood of reacting as +1 increases. The boron group is generally reactive, but properties vary by element, although all can react as +3.They have lower melting points than the other transition metals, and its fourth member, the highly radioactive element opernicium, is even predicted to be a metal gas. The volatile metals are also a subgroup of the transition metals.They are very good conductors of electricity, and silver (Ag, 47) is the best conductor of any element. The coinage metals are a subgroup in the transition metals.Technetium (Tc, 43) is radioactive, along with all the group 7 transition metals, and mercury (Hg, 80) is liquid at room temperature. Transition metals are what most people think of when they hear the word "metal." They are generally tough, stable, and hard to melt, with some exceptions.Alkaline earth metals are slightly less reactive than the alkali metals, but are still reactive and flammable, but less so than their neighbors.Some spontaneously burn in air, and they all react violently on contact with water. The alkali metals are extremely light, reactive, and soft metals.Highly reactive, very high electron affinities Metallic, high conductivity, moderately reactive, low melting pointsÄiverse properties, moderately nonreactiveÄiverse properties, reactive, high electron affinities Metallic, very high conductivity, nonreactive, high melting points Metallic, high densities, high conductivity, moderately reactive, high melting points, low electron affinities Shiny, silvery-white, high conductivity, reactive, low melting points, low electron affinities Shiny, soft, low densities, high conductivity, highly reactive, very low melting points, low electron affinities Some groups have names, which are dependent on chemical properties. Elements in the same group usually have similar chemical properties. Groups are ordered from 1 to 18 (New IUPAC numbering). ![]() For example, the alkali metal group, which contain sodium and potassium, are all shiny, soft, highly reactive, and have one valence electron in their outermost s-orbital. Periods are arranged by atomic number while groups are ordered by similar chemical properties. The Periodic Table is arranged by rows, also known as periods, and columns, which are also known as groups. Several of his predictions, for scandium (Sc, 21), gallium (Ga, 31), germanium (Ge, 32), technetium (Tc, 43), and protactinium (Pa, 91), accurately described the chemical properties of these undiscovered elements. Elements with similar chemical properties were grouped into families, while Mendeleev boldly left spaces blank for predicted elements yet to be discovered. Mendeleev's table grouped the elements into eight columns, rather than the now-conventional 18 column arrangement, in increasing order of atomic mass instead of atomic number. Previous efforts to order the elements had been attempted, but none had proven to be very successful. The first widely-accepted arrangement of the elements was created by the Russian chemistry professor Dimitri Mendeleev in 1869. Metals tend to be found more towards the left of the table while nonmetals tend to be found on the right, with metalloids in between, following a "staircase" pattern. The periodic table also contains four rectangular blocks with approximately similar properties. These periodic trends may increase, decrease, or stay consistent along a row or column. Other important factors in determining the arrangement of the elements include electron configurations and recurring chemical and physical properties. In the Periodic Table, pure elements are ordered in increasing order of atomic number, which is the number of protons in nucleus. Periodicity, the repetition of patterns at regular intervals, is the most important property of the Periodic Table. ![]()
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