Transition Elements Essays (419 words) - Periodic Table,

Transition Elements Transition Elements, series of chemical elements that share similar electron orbital structures and hence similar chemical properties. The transition elements are commonly defined as the 30 elements with atomic numbers 21 to 30, 39 to 48, and 71 to 80. The transition elements exhibit multiple valences or oxidation states typically ranging from +1 to +8 in compounds. In organometallic compounds, consisting of metals bonded to organic species, transition metals sometimes take on negative oxidation states. The transition elements have such typical metallic properties as malleability, ductility, high conductivity of heat and electricity, and metallic luster. They tend to act as reducing agents (donors of electrons), but are less active in this regard than the alkali metals and alkaline earth metals, which have valences of +1 and +2, respectively. There are exceptions, as in the case of mercury (Hg), which is a liquid Transition elements in general have high densities and melting points and exhibit magnetic properties. They form both ionic and covalent bonds with anions (negatively charged ions), and such compounds are in general brightly colored.. They have high electrical conductivity because of delocalization of the s electrons simil ar to what occurs in the alkali and alkaline-earth metals. Another characteristic of the transition metals is the great variety of oxidation states shown in its compounds. Several transition elements and their compounds are important catalysts (see Catalysis) in a variety of industrial processes, especially in the manufacture of petroleum and plastic products, where organic molecules are hydrogenated, oxidized, or polymerized (see Chemical Reaction; Hydrogenation; Polymer). Compounds of titanium, aluminum, or chromium are used in the polymerization of ethylene to form polyethylene. Catalysts containing iron are used in preparing ammonia from hydrogen and nitrogen. Molecules containing transition elements are important to the biochemical processes in many living systems, the most familiar example of which is the iron-containing heme complex of hemoglobin, which is responsible for oxygen transport in the blood of all vertebrates and some invertebrates. Most transition metals are colored and make some of their ionic compounds colored. This is because they absorb some of the frequencies of white light. This is attributed to electronic transitions in the d subshell, separating them into different levels of energy. When light is absorbed, an electron is raised from a lower state to a higher state, giving the rise to color. The stored energy is then dissipated through heat. The transition metals also have complex ionic structures because of the availability of d orbitals for participating in chemical bonding. Science

Searchers essays

Searchers essays The Searchers (1956) is one of America's top one-hundred films ever made. John Ford directed this film with John Wayne as the leading role, his supporting actors/actresses were Natalie Wood, Jeffery Hunter, Vera Miles, and Ward Bond.The film tells the story of a man, Wayne, searching for his captured nice, but actually is searching for his humanity. This film dones not focus on Wayne as a hero, as much as it does on him trying to find himself. The montage, visual elements, action, and sound elements are what makes this film so great. The montage, or narative continuity and character explination is what hooks the viewer into watching the film. Narative continuity is how the film flows, or how the story is told. Throughout the movie the story is told, or percieved as if the viewer were there experiencing it all. When Ethan(Wayne) is comes home and the whole family is sitting in the livingroom by the fire they are telling the story through their dialouge and the actions. There is a part in the film that is nariated though.When Marty sends the letter back home to Laurie to tell her about his journey, she reads the letter aloud to the family and that is how that part of the film is shown to the viewers. When she reads the part about him finding a wife, the film shows much more detail than she reads. Like him finding wife, the film shows how he got his wife, how she followed them, and how he lost her. Character explination allows the viewers to get to know the characters. Through out the film the viewers will get to know little bits and pieces of information about the main characters. They are not as obvious, so the viewer needs to read between the lines. At the very beginning of the film when Ethan returns home, his nephew Aaron asks him, "How was California," and Ethan replies, " California? How should I know?...No, I ain't been to California. I don't plan to go either." Then Aaron asks him to tell them about the war, so...