Groups of Elements – Ch. 5 CP Chemistry

Alkali Metals (Group 1A) Name “alkali” comes from Arabic word meaning “ashes” Very reactive – why? Soft, shiny, malleable, ductile, good conductors React with halogens to form “MX-type” compounds – ex. NaCl, LiCl, KI

Alkaline Earth Metals (Group 2A) Higher densities and melting points than alkali metals Not as reactive as alkali metals (higher ionization energies) Form MX 2 -type compounds with halogens (MgCl 2 ) Found in seawater, mineral deposits

Transition Metals (d-block elements) High densities, high melting points Exhibit colors due to d electrons Examples – iron, copper, silver, gold

Inner Transition Metals (f-block elements) 4f: Lanthanides –Soft, silver-colored metals –Form 3 + ions –Somewhat reactive 5f: Actinides –Radioactive –Few exist naturally

P-block Elements Boron Group (3A) –Comprised of semimetal (B) and metals –Form 3 + ions –Al is abundant Carbon Group (4A) –Includes nonmetal, semimetals, and metals –Carbon, Silicon very abundant

P-block elements (continued) Nitrogen Group (5A) –Form 3 - ions –Includes nonmetals, semimetals, and a metal (Bi) –Nitrogen is most abundant element in Earth’s atmosphere –Phosphorus, Nitrogen both biologically important

P-block elements (continued) Oxygen group (6A) –Oxygen is most abundant element on Earth –Elemental oxygen is reactive –Sulfur is also reactive; sulfuric acid is used in manufacturing

P-Block Halogens (Group 7A) –Comes from Greek “salt former” –Nonmetals –Exist as diatomic molecules –Highly reactive – react with metals and nonmetals – due to strong electronegativity/electron affinity –Form halides (1 - ions)

Noble Gases (8A) Least reactive elements Ar – makes up 1% of Earth’s atmosphere No known compounds of He, Ne, Ar

Hydrogen Nonmetal, gas at room temperature, colorless, odorless Most abundant element in universe, but rare in our atmosphere