7 The Elements

Properties of s-Block Elements There are 92 naturally occurring elements. Elements with atomic numbers greater than 92 do not exist in nature. These synthetic elements are created in labs or nuclear reactors. Elements within the same group on the periodic table have the same number of valence electrons and similar physical and chemical properties. Metals tend to lose electrons, which makes them their ionization energy low and causes them to be more reactive. Nonmetals tend to gain electrons, which makes their ionization energy high and causes them to be more reactive.

Group 1A: Alkali Metals Group 1A metals React with water to form alkaline solutions. Easily lose a valence electron forming an ion with a 1+ charge. Good conductors of heat and electricity. Found combined with other elements in nature.

Group 2A: Alkaline Earth Metals Group 2A elements form compounds with oxygen, called oxides and produce alkaline solutions when they react with water. Found combined with oxygen and other nonmetals in Earth’s crust. Lose their two valence electrons to form ions with a 2+ charge.

Properties of p-Block Elements Some p-Block elements are metals, some are metalloids, and some nonmetals. Metalloids are elements with metal and nonmetal properties. Some are solids and some are gases at room temperature. Many form more than one type of ion. Elements in Groups 3A, 4A, 5A, 6A, 7A, 8A (except He).

Group 3A: The Boron Group Group 3A elements are always found combined with other elements in nature. Most often found as oxides in Earth’s crust. These elements lose 3 valence electrons to form 3+ ions, except for Thallium (which forms a 1+ ion). Boron (metalloid) Aluminum (abundant metal) Gallium, indium, and thallium (rare metals)

Group 4A: The Carbon Group The period-2 element, carbon, does not represent the characteristics of the whole group. Few rules apply to all the elements in the group. Carbon (nonmetal) Silicon and Germanium (metalloids) Lead and Tin (metals)

Group 5A: The Nitrogen Group Each element in group 5A has five valence electrons. They display a wide variety of physical and chemical properties. Nitrogen Phosphorus Arsenic Antimony Bismuth

Group 6A: The Oxygen Group With six valence electrons the elements act mainly as nonmetals. They gain two electrons to form ions with a 2- charge and can share two electrons to achieve a stable electron configuration. Polonium, selenium and tellurium Oxygen Sulfur Selenium

Group 7A: The Halogens Named for their ability to form compounds, called salts, with almost all metals. (ex. Sodium chloride – table salt) Reactive nonmetals always found combined with other elements in nature Their physical properties differ, but chemical behavior is similar with astatine as one exception. It is radioactive with no known uses. They tend to share or gain one electron to form 1- ions. Chlorine – gas at room temperature Bromine – liquid, evaporates easily Iodine – solid that can change directly into a vapor (sublimate/sublimation)

Group 8A: Noble Gases Colorless and unreactive due to their highly stable electron configurations. (Outer shells filled to the maximum quantity of 8 electrons, except for Helium) No known compounds of helium, neon, or argon. Helium Neon Argon Krypton Radon

Properties of d-Block and f-Block Elements Transition metals (d-block) Inner transition metals (f-block)

Transition Metals They share properties such as electrical conductivity, luster, and malleability. Most are hard solids with relatively high boiling and melting points. (Zinc has the lowest and is relatively soft.) They lose two electrons to form 2+ ions, but can form ions with charges as high as 6+. Copper, silver, gold, platinum, and palladium are the only transition metals found in nature not combined with other elements. All other transition metals are found combined with minerals such as oxides and sulfides. Minerals are mixed with other materials in ores and the field of metallurgy focuses on removing these metals from those ores.

Inner Transition Metals Lanthanide series – silvery metals with relatively high melting points. They are found mixed together in nature and are very difficult to separate. Actinide series – radioactive elements; only three exist in nature. The rest are synthetic elements called transuranium elements (because their atomic numbers come after uranium/are greater than 92), which are created in particle accelerators or nuclear reactors. Most decay quickly, with one exception, plutonium-239.