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Tour of the Periodic Table Main Block Elements • The elements in the s and p block are called the main block elements (also known as the main group elements) • These will be filling up the outermost shell Alkali Metals • Group 1 • Highly reactive with water • http://www.youtube.com/watch?v=Ft4E1eCUItI • They have one electron in their valence shell • They are soft, with low melting and boiling temperatures • Alkali metals color flames – Li red Na yellow K lilac Rb red Cs blue Alkaline Earth Metals • Group 2 Elements • They are filling the s orbital – Have 2 electrons in their valence shell • Very reactive (less than Alkali Metals) – Usually found in compounds • harder and denser than sodium and potassium, and have higher melting points • Characteristic colors when heated in a flame: – Mg brilliant white Ca brick-red Sr crimson Ba apple green Halogens • Group 17 • Most reactive non-metals • Full s orbital, and only missing one electron in the p orbital (7 electrons in the valence shell) • Most often bonded to Alkali Metals • At room temperature all the halogens exist as diatomic molecules • http://www.youtube.com/watch?v=yP0U5rGWqdg Noble Gases • Group 18 • Full Valence Shell – Full s and p orbitals • Non-Reactive • Once called inert gases, but found some compounds will form, although very few Hydrogen • 1st element on the periodic table • Does not really fall into any category • Sometimes acts as a metal, sometimes acts as a non-metal • Highly explosive • http://www.youtube.com/watch?v=bgGlE97rJl4 • http://www.youtube.com/watch?v=4nL4iuE2Fqo&feature=related Metals • Most of the elements are metals Metals • Physical Properties of Metals: – Luster (shininess) – Good conductors of heat and electricity – High density (heavy for their size) – High melting point – Ductile (most metals can be drawn out into thin wires) – Malleable (most metals can be hammered into thin sheets) • Chemical Properties of Metals: – Easily lose electrons – Corrode easily. Corrosion is a gradual wearing away. (Example: silver tarnishing and iron rusting) Metals • Transition Metals – Summary of Common Properties • Low ionization energies • Positive oxidation states • Very hard • High melting points • High boiling points • High electrical conductivity • Malleable • Five d orbitals become more filled, from left to right on periodic table Metals • These common properties apply to both the lanthanides and actinides. – The rare earths are silver, silvery-white, or gray metals. – The metals have a high luster, but tarnish readily in air. – The metals have high electrical conductivity. – The rare earths share many common properties. This makes them difficult to separate or even distinguish from each other. – There are very small differences in solubility and complex formation between the rare earths. – The rare earth metals naturally occur together in minerals (e.g., monazite is a mixed rare earth phosphate). – Rare earths are found with non-metals, usually in the 3+ oxidation state. There is little tendency to vary the valence. (Europium also has a valence of 2+ and cerium also a valence of 4+.) Metalloids • Elements on both sides of the zigzag line have properties of both metals and nonmetals. These elements are called metalloids. • Physical Properties of Metalloids: – Solids – Can be shiny or dull – Ductile – Malleable – Conduct heat and electricity better than nonmetals but not as well as metals Nonmetals • Nonmetals are found to the right of the stair-step line. Their characteristics are opposite those of metals. – Physical Properties of Nonmetals: • No luster (dull appearance) • Poor conductor of heat and electricity • Brittle (breaks easily) • Not ductile • Not malleable • Low density • Low melting point – Chemical Properties of Nonmetals: • Tend to gain electrons • Since metals tend to lose electrons and nonmetals tend to gain electrons, metals and nonmetals like to form compounds with each other. These compounds are called ionic compounds. When two or more nonmetals bond with each other, they form a covalent compound.
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