Oxygen Facts - Periodic Table of the Chemical Elements

Oxygen is the element with atomic number 8 and element symbol O. Under ordinary conditions, it can exist as a pure element in the form of oxygen gas (O2) and also ozone (O3). Here is a collection of facts about this essential element. Oxygen  Basic Facts Atomic Number: 8 Symbol: O Atomic Weight: 15.9994 Discovered By:  Credit for the discovery of oxygen is usually given to Carl Wilhelm Scheele. However, there is evidence credit should be given to the Polish alchemist and physician Michael Sendivogius. Sendivogius 1604 work  De Lapide Philosophorum Tractatus duodecim e naturae fonte et manuali experientia depromt,  he describes cibus vitae or food of life. He isolated this substance (oxygen) in experiments conducted between 1598 and 1604 involving the thermal decomposition of potassium nitrate or saltpeter. Discovery Date: 1774 (England/Sweden) or 1604 (Poland) Electron Configuration: [He]2s22p4 Word Origin:  The word oxygen comes from the Greek oxys, meaning sharp or acid and genes, meaning born or former. Oxygen mean acid former. Antoine Lavoisier coined the term oxygen in 1777 during his experiments exploring combustion and corrosion. Isotopes: Natural oxygen is a mixture of three stable isotopes: oxygen-16, oxygen-17, and oxygen-18. Fourteen radioisotopes are known. Properties: Oxygen gas is colorless, odorless, and tasteless. The liquid and solid forms are a pale blue color and are strongly paramagnetic. Other forms of solid oxygen appear red, black, and metallic. Oxygen supports combustion, combines with most elements, and is a component of hundreds of thousands of organic compounds. Ozone (O3), a highly active compound with a name derived from the Greek word for I smell, is formed by the action of an electrical discharge or ultraviolet light on oxygen. Uses: Oxygen was the atomic weight standard of comparison for the other elements until 1961 when the International Union of Pure and Applied Chemistry adopted carbon 12 as the new basis. It is the third most abundant element found in the sun and the earth, and it plays a part in the carbon-nitrogen cycle. Excited oxygen yields the bright red and yellow-green colors of the Aurora. Oxygen enrichment of steel blast furnaces accounts for the greatest use of the gas. Large quantities are used in making synthesis gas for ammonia, methanol, and ethylene oxide. It is also used as a bleach, for oxidizing oils, for oxy-acetylene welding, and for determining carbon content of steel and organic compounds. Biology: Plants and animals require oxygen for respiration. Hospitals frequently prescribe oxygen for patients. Approximately two thirds of the human body and nine tenths of the mass of water is oxygen. Element Classification: Oxygen is classified as a nonmetal. However, it should be noted a metallic phase of oxygen was discovered in 1990. Metallic oxygen forms when solid oxygen is pressurized above 96 GPa. This phase, at very low temperatures, is a superconductor. Allotropes: The usual form of oxygen near the Earths surface is dioxygen, O2. Dioxygen or gaseous oxygen is the form of the element used by living organisms for respiration. Trioxygen or ozone (O3) is also gaseous at ordinary temperatures and pressure. This form is highly reactive. Oxygen also forms tetraoxygen, O4, in one of the six phases of solid oxygen. There is also a metallic form of solid oxygen. Source: Oxygen-16 is formed primarily in the helium fusion process and neon burning process of massive stars. Oxygen-17 is made during the CNO cycle when hydrogen is burned into helium. Oxygen-18 forms when nitrogen-14 from CNO burning fuses with a helium-4 nucleus. Purified oxygen on Earth is obtains from air liquefaction. Oxygen Physical Data Density (g/cc): 1.149 ( -183 °C) Melting Point ( °K): 54.8 Boiling Point ( °K): 90.19 Appearance: Colorless, odorless, tasteless gas; pale blue liquid Atomic Volume (cc/mol): 14.0 Covalent Radius (pm): 73 Ionic Radius: 132 (-2e) Specific Heat (20 °C J/g mol): 0.916 (O-O) Pauling Negativity Number: 3.44 First Ionizing Energy (kJ/mol): 1313.1 Oxidation States: -2, -1 Lattice Structure: Cubic Lattice Constant (Ã…): 6.830 Magnetic Ordering: Paramagnetic Quiz: Ready to test your oxygen facts knowledge? Take the Oxygen Facts Quiz.Back to the Periodic Table of the Elements Sources Dole, Malcolm (1965). The Natural History of Oxygen (PDF). The Journal of General Physiology. 49 (1): 5–27. doi:10.1085/jgp.49.1.5Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 793. ISBN 0-08-037941-9.Priestley, Joseph (1775). An Account of Further Discoveries in Air.  Philosophical Transactions.  65: 384–94.  Weast, Robert (1984). CRC, Handbook of Chemistry and Physics. Boca Raton, Florida: Chemical Rubber Company Publishing. pp. E110. ISBN 0-8493-0464-4.

The Family A Historical Review - 2353 Words

The Family: A Historical Review 1.1 Introduction The family is an important social institution. The concept of family is found in every known society (Murdock, 1949:1). Anthropologists classify family as individuals related by blood and marriage (Haviland 1996:230); nevertheless there remains no universal definition of the family. The forms a family might take (nuclear or extended, polygamous or monogamous) vary across cultures and time (Murdock, 1949:1). It performs six universal functions to satisfy the needs of its members, such as, reproduction, protection, socialization, regulation of sexual behaviour, attention and companionship, and providing social status (Ogburn Tibbits, 1934). The definition of the family often determines†¦show more content†¦Physical, sexual and emotional abuses are a common occurrence in many families with women and children as the main victims and men the perpetrators. Therefore, it is important to conduct a historical review of the family, as the hierarchal relation that it establishes between husband and wife will provide a better understanding of the acceptability of domestic violence throughout society and how it has come to be seen as a private matter. 1.2 Historical Review of the Brazilian Family A unitary explanation or description cannot be given for the Brazilian family structure due to its diversity racially, ethnically and socio-economically. From its inception, black slaves and descendants of African origin, Natives from several nations, and Whites from European have comprised the creation of the Brazilian nation thus, no single Brazilian family model historically (Torres Dessen, 2008:196). I will try to be succinct while I showcase the different models based on class and ethnic diversity. In looking at the historical Brazilian family structure, there are two models based on ethnic-cultural diversity. Neder (as cited in Torres Dessen, 2008) notes that the first type of Brazilian family is from the family of African slaves who are also culturally diverse. Consequently, they also do not have a single African family structure but variety of family structures, such as matriarchy, patriarchy and polygamy (196). The second

Wireless Communications and Networksright Free Essays

Assignment 1 Wireless Communications and Networksright 6156960 Name : Sikandar ALI. Roll no. : FA14-BCS-095. We will write a custom essay sample on Wireless Communications and Networksright or any similar topic only for you Order Now Section: A. Submitted to : Sir aMMAR YASIR. Date : 2nd March , 2018.1000000 Name : Sikandar ALI. Roll no. : FA14-BCS-095. Section: A. Submitted to : Sir aMMAR YASIR. Date : 2nd March , 2018. Communication is a Latin word which means â€Å"sharing†. It means sharing some data or information from one place to another or with someone. The main source of communication is language. There are some other ways for communicating like:The use of Symbols.Road signs for the movement of vehicles.In military defense, we use secret codes for confidential communication. Types of Communication: There are three types of communication:Verbal Communication.Non-Verbal Communication.Visual Communication.Verbal Communication:The communication which is in formal way to exchange or communicate from one person to another. It has further two types:Written Communication: The communication which is in written form like documents , emails , chats , SMS. This kind of communication is also used in business proposal, issusing legal instructions contracts, memes. To make effective written communication, it depends on vocabulary, styles, clarity and also grammer.Oral Communication: The communication which is face to face of spoken words. It could also be on phone call, audio/video call and also video conference through internet. People give interviews to international companies for job on Skype. It could be formal or informal communication. Formal Communication: The communication in which conferences, lectures takes place.Informal Communication: The communication in which gossips with friends, crack jokes takes place.Non-Verbal communication:The communication which is in formal way to exchange or communicate from one person to another. This communication can be done by body language which includes facial expressions, eye contact, body posture, gestures and others. But the most common of all is facial expressions.Visual Communication:A communication in which an idea or information that can be read or viewed by using visual aids like drawing, signs, typography, graphic design and other electronic devices. The profit and loss of business can be view by graphs or charts through which employees can present the profit and loss of business very easily.Wireless Communication:A communication in which data or information can be send or receive without any cables or wires to another device. The information is transmitted through air by electromagnetic waves like radio frequency, infrared, satellite and much more. Now there are variety of devices and technologies ranging from smartphones to laptops, tablets, printers, bluetooth, Wi-Fi, 3G and 4G etc. Types of Wireless Communication: There are three types of Wireless Communication:Wireless Personal Area Network (WPAN).Wireless Local Area Network (WLAN).Wireless Metropolitan Area Network (WMAN). Wireless Personal Area Network (WPAN):The system which connect two devices at very short range. They must be very close to each other usually in the same room. Bluetooth: It is two way communication between two devices which could be place very close to each other for sharing data or any information. It is very efficient reducing the wires like connect a mouse with computer, headphones, MP3 and cellphones etc. Infrared (IR) Wireless Communication: In this system, data or information is carried over infrared waves between two points. The frequency range is in between the microwave and visible light. These are very small range of distance like TV remote and AC remote. Wireless Local Area Network (WLAN):It is local area network which connects two or more transceivers by using a wireless device. It covered the house or small offices under the WLAN.Wi-Fi: A system that is related to computer networking. In this, we need wired connection of internet with guided router which connects to other devices like mobile, laptops, tablets and LED TV. It’s range is generally one home or small offices. If we use in large campus or hospitals then we use range extender to make the range much more and cover the whole area under the network. Wireless Metropolitan Area Network (WMAN):It is the communication network which have to covered the large areas , states or countries to communicate with each other. For this purpose, we use satellite communication or transmission tower to communicate with other very long range places and take care by service provider. Satellite Communication:An artificial satellite that provide us facilities for communication as radio, television, telephones transmission and communicate with other countries by video or audio calling, texting and so on.The heart of a satellite communication system is a satellite based antenna in a stable orbit above the Earth. There are many satellites that relays on the space to communicate with each other as serve as relay station in space. The antenna station on near the Earth are referred to as â€Å"Earth Stations†. A transmission from an Earth station to the satellite is referred as â€Å"Uplink†. A transmission from satellite to an Earth station is referred as â€Å"Downlink†. The component in satellite which takes an uplink and convert into downlink signals is known as â€Å"Transponder†. There are number of ways of categorizing satellite communication:-Coverage Area:It covers the global, regional and national. The larger the area of coverage, the more satellites must be involved in a single networked system.Service Type:Fixed service satellite, broadcast service satellite and mobile service satellite. General Usage:Commercial, Military, Amateur and Experimental.Protocols for Satellite Communication: The protocols for Satellite Communication are these:MPEG : It stands for Motion Picture Expert Group. It is the dominant standard used for TV encoding and transmission.IP : It stands for Internet Protocol. It is the entire family of data communication protocols which is popular for emails and web-browsing. Why use of Satellite Communication? We use satellite communication for television, telephones, navigations, business and finance, weather, safety, development and a lot of more. Let us take some scenario to show why we use satellite communication?Scenario:If we talk about television, you watch TV and there are hundred of channels on TV which are broadcast from many countries and there are some news channels, movies channels, drama channels, sports channels and also animated channels for children. People get to know about the situation of other countries through news if there will be no satellite then there will be no broadcast and no channel will appear on TV. If we talk about Telephones, we can call on airplanes through flight phone communication which is provided by satellites to communicate with rural areas. Also through satellite, we can make our audio and video calls and talk from one country to another. If we talk about navigators, when you like to visit a place with friends and family but you lost the way that which is the right one. So, you use navigator which is in your cellphone and connect it with GPS through satellite to know about your location which is very helpful to get the right path and you can easily reach to your destination without any problem. Advantages of Satellite Communication:It is use for wireless communication.It is use for navigation.It covers the wide area of region or country with one satellite It is also use for audio/video calls and for transmission of data.It is use for connecting small areas, broadcasting TV/radio and also tell us about weather situations. How to cite Wireless Communications and Networksright, Papers