ELEMENTS: CHEMICAL & PHYSICAL PROPERTIES

GROUP 1 Alkali Metals Potassium reaction with water Sodium reaction Are not found as elements in nature Stored under kerosene or other hydrocarbon solvent (oil) Can react with water vapor or oxygen in the air Good conductors of electricity and heat Ductile, malleable, and soft Silvery luster Low density Low melting point Form: colorless ions with a 1+ charge ionic compounds water-soluble bases Potassium reaction with water Sodium reaction with air

GROUP 2 Alkaline Earth Metals Are not found as elements in nature Occur most commonly as carbonates, phosphates, silicates, and sulfates Good conductors of electricity and heat Ductile and malleable Silvery luster Includes naturally radioactive element radium Form: less reactive than alkali metals rxn with HOH to form bases & hydrogen gas compounds are insoluble or only slightly soluble in water forms primarily ionic compounds ions with a 2+ charge Beryl A source of beryllium

GROUPS 3 – 12 Transition Metals Usually harder, more brittle than Groups 1 & 2 metals Higher melting & boiling points than Groups 1 & 2 metals Good conductors of electricity and heat Malleable and ductile Silvery luster, except copper & gold Chemical properties differ from each other Include radioactive elements 89-112 Compounds often colored May form complex ions 1 or 2 valence electrons Usually have ≥ 2 common oxidation states Includes mercury, only metal that is liquid at room temperature ↓ Transition metals

GROUP 13 Boron Family are not found as elements in nature scarce in nature metallic solids soft, low melting points chemically reactive at moderate temperatures 3 valence electrons Exceptions: aluminum: most abundant metallic element which exists as ore bauxite, is self-protecting boron: metalloid, covalent solid, hard, high melting point, not chemically reactive at moderate temperatures

GROUP 14 Carbon Family nonmetal: carbon metalloids: silicon, germanium metals: tin, lead large variation in physical & chemical properties occurs in elemental & combined forms relatively unreactive 4 valence electrons tend to form covalent compounds although tin and lead will form ionic compounds Tin and lead are self-protecting metals

GROUP 15 Nitrogen Family nonmetals: nitrogen, phosphorus metalloids: arsenic, antimony metal: bismuth Most common forms: nitrogen: atmospheric N2 phosphorus: phosphate rock arsenic, antimony, bismuth: sulfides or oxides antimony, bismuth: elements abundant : nitrogen, phosphorus rare: arsenic, antimony, bismuth form covalent compounds, oxidation numbers usually +3 or +5 atoms have 5 electrons in their outermost energy level Exist in ≥2 allotropic forms except nitrogen & bismuth Solids at room temperature, except nitrogen

GROUP 16 Oxygen Family nonmetal: oxygen, sulfur, selenium metalloid: tellurium metal: polonium occur as elements & in combined states form covalent compounds, oxidation numbers usually -2 atoms have 6 electrons in outermost energy shell often exist as diatomic & polyatomic molecules (i.e. O2, S6) exist in several allotropic forms (i.e. sulfur can exist as orthorhombic or monoclinic crystal structure)

GROUP 17 Halogens all nonmetals occur in combined form, usually as metal halides found in rocks of Earth’s crust & dissolved in sea water At room temperature --- gas: F2 Cl2 liquid: Br2 solid: I2 all reactive, esp. fluorine Atoms have 7 electrons in outermost energy level Usually gain an electron to form a halide, X- ion, but can share electrons & have positive oxidation states

GROUP 18 Noble Gases inert essentially demonstrate ideal gas behavior over a wide range of temperatures & pressures group has highest ionization energy, therefore strongly resist losing electrons complete octet of electrons in highest energy level gases at room temperature 1st noble gas compound prepared in 1962, XeF4 Neon, Argon, Krypton Xenon used in lighting Helium used in balloons since less dense than air