Group 16 - Oxygen Family PDF

Inorganic Chemistry II (Chem 3120) Dr/ Amal Nassar Chemistry Department, College of Sciences and Humanities, Prince Sattam bin Abdulaziz University. 1  Group 6A(16): The Oxygen Family Chalcogens group Mr R. Tucke...

Inorganic Chemistry II (Chem 3120) Dr/ Amal Nassar Chemistry Department, College of Sciences and Humanities, Prince Sattam bin Abdulaziz University. 1  Group 6A(16): The Oxygen Family Chalcogens group Mr R. Tucker (PP02_2005) Group 6A(16): The Oxygen Family Six chemical elements in Group 16 (VIA) of the periodic classification namely, oxygen (O), sulfur (S), selenium (Se) are nonmetals tellurium(Te), polonium (Po) are metalloids  Group 6A(16): The Oxygen Family  Group 6A (or VIA) of the periodic table are the chalcogens: the nonmetals oxygen (O), sulfur (S), and selenium (Se), the metalloid tellurium (Te), and polonium (Po) the metal. The name "chalcogen" means "ore former," derived from the Greek words chalcos ("ore") and -gen ("formation").  The group 6A elements have outer-electron configuration ns2np4, these elements may reach a noble-gas electron configuration by the addition of two electrons, which results in a -2-oxidation state, this is a common oxidation state.  Except for oxygen, the group 6A elements are also commonly found in positive oxidation states up to +6, such as SF6, SeF6, and TeF6 occur in which the central atom is in the +6-oxidation state. Group 6A(16): The Oxygen Family Natural Occurrence And Uses  Oxygen is represented in the air, oxygen exists mostly as molecules (O 2), although small amounts of ozone (O3), in which three atoms of oxygen make up each molecule, are present in the atmosphere. Oxygen is a colorless, odorless, tasteless gas essential to living organisms, being taken up by animals, which convert it to carbon dioxide; plants use carbon dioxide as a source of carbon and return the oxygen to the atmosphere.  Group 6A(16): The Oxygen Family Sulfur is ninth among the elements, occurs in the uncombined state as well as in combination with other elements in rocks and minerals. Sulfur used to produce sulfuric acid, one of the most used chemicals in the world(manufacture of paints, fertilizers, detergents, synthetic fibers, and rubber). Sulfur has more than 10 different forms, due to the ability of S to catenate. Selenium is much rarer than oxygen or sulfur, sometimes It is found uncombined, accompanying native sulfur. Selenium conducts electricity when exposed to light, so it is used in solar cells, light meters, and photographic materials. Selenium has several allotropes, some consisting of crown-shaped Se8 molecules. Group 6A(16): The Oxygen Family  Tellurium is a silvery-white rarer element with properties intermediate between those of metals and nonmetals.  Polonium is an extremely rare, radioactive element found in minerals containing uranium.  Oxygen (O2) Properties Oxygen is most common and important component of air, it Discovered by: Joseph Priestley, Carl Scheele in Sweden 1774 It is highly reactive nonmetallic element react with all other elements heavier than air. Gas has colorless, odorless and tasteless soluble in water without smell or taste Has highly electronegative and oxidizing agent. Oxygen is the most abundant element by mass in the Earth‘s crust as part of oxide compounds such as silicon dioxide. Oxygen is essential for life, it is necessary for aerobic respiration  Oxygen (O2) When oxygen is cooled to -183℃, it becomes a liquid. Liquid oxygen is used as a propellant for rockets Oxygen becomes solid at temperatures below -218 ℃. In both its liquid and solid states, the substances are clear with a light sky-blue color. Oxygen has two allotropes: diatomic O2 which is essential to life and triatomic O3 (ozone) which is poisonous and important because it shields living organisms from some harmful radiation from the Sun. produced by plants during photosynthesis 6 CO2 + 6 H2O + photons → C6H12O6 + 6 O2 it is necessary for aerobic breathing in plant and living organism. C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + 2880kJ·mol−1  Oxygen (O2) Preparation large number of different methods for its preparation 1- Thermal decomposition of certain salts, such as potassium chlorate or potassium nitrate: 2KClO3 ==> 2KCl + 3O2 2KNO3 ==> 2KNO2 +O2 2- Thermal decomposition of metal peroxides or of hydrogen peroxide: 2H2O2 ==> 2H2O + O2 3- Thermal decomposition of oxides of heavy metals: 2Ag2O ==> 4Ag + O2  Oxygen (O2) Classification of oxides Oxygen is highly reactive element and form oxides with almost all elements except noble gases, there are 5 types of oxides: 1- Acidic Oxides Acidic oxides: is oxides of non-metals such CO2, SO3 These oxides react with water forming acids: CO2+H2O→H2CO3 (Carbonic Acid ) SO3+H2O→H2SO4 (Sulfuric Acid) When these oxides combine with bases, they produce salts, e.g. SO3+NaOH→Na2SO4+H2O  Oxygen (O2) 2- Basic Oxides Basic oxides are the oxides of metals, such as K2O and CaO. they react with water to produce hydroxides CaO+H2O→Ca(OH)2 (Hydroxide calcium) K2O(s)+H2O(l)→2KOH(aq) (Hydroxide potacium) When these oxides combine with acids, they produce salts, e.g. CaO+2HCl→CaCl2 + H2O 3- Neutral Oxides These are nonmetallic oxides, which show neither basic nor acidic properties. They do not form salts when reacted with acids or bases e.g., carbon monoxide (CO); nitrous oxide (N2O); nitric oxide (NO).  Oxygen (O2) 4- Amphoteric oxides Amphoteric oxides are metallic oxides, which show both basic as well as acidic properties. When they react with an acid, they produce salt and water, showing basic properties. While reacting with alkalies they form salt and water showing acidic properties, e.g., Al2O3 + 3H2SO4 →Al2(SO4)3 + 3H2O (basic nature) Al2O3 + 2NaOH →2NaAlO2 + H2O (acidic nature) 5- Peroxides Peroxides are a group of oxidess with the structure [O−O]-2 The O−O group in a peroxide is called the peroxide group or peroxo group. The most common peroxide is hydrogen peroxide (H2O2) H2 + O2→H2O2  Oxygen (O2) 6- Compound oxides Compound oxides are metallic oxides that made up of two oxides, one that has a lower oxidation and one with a higher oxidation of the same metal, e.g., Ferro-ferric oxide: Fe3O4= Fe2O3 + FeO On treatment with an acid, compound oxides give a mixture of salts. Fe3O4 + 8HCl→ 2FeCl3 +FeCl2+4H2O  Oxygen (O2) Applications  oxygen is essential to breathing.  Oxygen also is required for combustion to occur.  used in medicine  used in welding and cutting (3,500 °C)  making of steel and methanol  Melting process