Reactivity Definition in Chemistry

Reactivity Definition in Chemistry In chemistry, reactivity is a measure of how readily a substance undergoes a chemical reaction. The reaction can involve the substance on its own or with other atoms or compounds, generally accompanied by a release of energy. The most reactive elements and compounds may ignite spontaneously or explosively. They generally burn in water as well as the oxygen in the air. Reactivity is dependent upon temperature. Increasing temperature increases the energy available for a chemical reaction, usually making it more likely. Another definition of reactivity is that it is the scientific study of chemical reactions and their kinetics. Reactivity Trend in the Periodic Table The organization of elements on the periodic table allows for predictions concerning reactivity. Both highly electropositive and highly electronegative elements have a strong tendency to react. These elements are located in the upper right and lower left corners of the periodic table and in certain element groups. The halogens, alkali metals, and alkaline earth metals are highly reactive. The most reactive element is fluorine, the first element in the  halogen group.The most reactive metal is francium, the last alkali metal. However, francium is an unstable radioactive element, only found in trace amounts. The most reactive metal that has a stable isotope is cesium, which is located directly above francium on the periodic table.The least reactive elements are the noble gases. Within this group, helium is the least reactive element, forming no stable compounds.Metal can have multiple oxidation states and tend to have intermediate reactivity. Metals with low reactivity are called noble metals.  The least reactive metal is platinum, followed by gold. Because of their low reactivity, these metals dont readily dissolve in strong acids. Aqua regia, a mixture of nitric acid and hydrochloric acid, is used to dissolve platinum and gold. How Reactivity Works A substance reacts when the products formed from a chemical reaction have lower energy (higher stability) than the reactants. The energy difference can be predicted using valence bond theory, atomic orbital theory, and molecular orbital theory. Basically, it boils down to the stability of electrons in their orbitals. Unpaired electrons with no electrons in comparable orbitals are the most likely to interact with orbitals from other atoms, forming chemical bonds. Unpaired electrons with degenerate orbitals that are half-filled are more stable but still reactive. The least reactive atoms are those with a filled set of orbitals (octet). The stability of the electrons in atoms determines not only the reactivity of an atom but its valence and the type of chemical bonds it can form. For example, carbon usually has a valence of 4 and forms 4 bonds because its ground state valence electron configuration is half-filled at  2s2  2p2. A simple explanation of reactivity is that it increases with the ease of accepting or donating an electron. In the case of carbon, an atom can either accept 4 electrons to fill its orbital or (less often) donate the four outer electrons. While the model is based on atomic behavior, the same principle applies to ions and compounds. Reactivity is affected by the physical properties of a sample, its chemical purity, and the presence of other substances. In other words, reactivity depends on the context in which a substance is viewed. For example, baking soda and water are not particularly reactive, while baking soda and vinegar readily react to form carbon dioxide gas and sodium acetate. Particle size affects reactivity. For example, a pile of corn starch is relatively inert. If one applies a direct flame to the starch, its difficult to initiate a combustion reaction. However, if the corn starch is vaporized to make a cloud of particles, it readily ignites. Sometimes the term reactivity  is also used to describe how quickly a material will react or the rate of the chemical reaction. Under this definition the chance of reacting and the speed of the reaction are related to each other by the rate law: Rate k[A] Where rate is the change in molar concentration per second in the rate-determining step of the reaction, k is the reaction constant (independent of concentration), and [A] is the product of the molar concentration of the reactants raised to the reaction order (which is one, in the basic equation). According to the equation, the higher the reactivity of the compound, the higher its value for k and rate. Stability Versus Reactivity Sometimes a species with low reactivity is called stable, but care should be taken to make the context clear. Stability can also refer to slow radioactive decay or to the transition of electrons from the excited state  to less energetic levels (as in luminescence). A nonreactive species may be called inert. However, most inert species actually do react under the right conditions to form complexes and compounds (e.g., higher atomic number noble gases).

Names of Family Members in Spanish

Names of Family Members in Spanish Who are the members of your family, how many are there, and what do they do? These are among the first questions you may be asked when you meet and first become acquainted with a native Spanish speaker. Depending on your age, you may be asked about your parents and what they do for a living, or you may be asked if you are married or have any children. Learn the words on this page as well as a few words to describe your family members, then bring a photo along, and even if youre a beginner and know only simple grammar, you can engage in conversation. Gender and Family Members Keep in mind that masculine plurals in Spanish can refer to mixed groups of males and females. Thus cuatro hijos can mean either four sons or four children, depending on the context. And while it may sound strange to the ear attuned to English, padres is a grammatically correct way to refer to both a mother and father, even though padre alone refers to a father. Also, note that the word pariente means relative in general; the Spanish-English cognate  doesnt refer only to parents. Vocabulary of the Family Following are the names for the most common relatives and some of the uncommon ones: padre: fathermadre: motherhermano: brotherhermana: sistersuegro: father-in-lawsuegra: mother-in-lawcuà ±ado: brother-in-lawcuà ±ada: sister-in-lawesposo, marido: husbandesposa, mujer: wifeabuelo: grandfatherabuela: grandmotherbisabuelo: great-grandfatherbisabuela: great-grandmothertatarabuelo: great-great-grandfathertatarabuela: great-great-grandmotherhijo: sonhija: daughternieto: grandsonnieta: granddaughterbisnieto: great-grandsonbisnieta: great-granddaughtertataranieto: great-great-grandsontataranieta: great-great-granddaughtertà ­o: uncletà ­a: aunttà ­o abuelo: great-uncletà ­a abuela: great-auntprimo: cousin (male)prima: cousin (female)primo carnal, prima carnal, primo hermano, prima hermana: first cousinprimo segundo, prima segunda: second cousinsobrino: nephewsobrina: niecepadrastro: stepfathermadrastra: stepmotherhijastro: stepsonhijastra: stepdaughterhermanastro: stepbrotherhermanastra: stepsistermedio hermano, hermano de padre, hermano de madre: half brothermedia her mana, hermana de padre, hermana de madre: half sister concuà ±ado: husband of ones spouses sisterconcuà ±ada: wife of ones spouses brotherconsuegro: father-in-law of ones son or daughterconsuegra: mother-in-law of ones son or daughterprometido, novio: fiance, boyfriend, groomprometida, novia: fiancà ©e, girlfriend, bridecompaà ±ero: male partner in a couple relationshipcompaà ±era: female partner in a couple relationshippadrino: godfathermadrina: godmotherahijado: godsonahijada: goddaughteramigo: friend (male)amiga: friend (female)conocido: acquaintance (male)conocida: acquaintance (female) Miscellaneous Family Terms La familia polà ­tica  or los polà ­ticos may be used as the equivalent of the in-laws. In other words, the terms refer to people to whom one is related by marriage. (In a different context, polà ­ticos can also refer to politicians.) The term amigovio or amigovia can be used colloquially in some areas to a person with whom a person has a romantic or sexual relationship that hasnt necessarily been formalized, such as a friend with benefits or a live-in lover where there isnt necessarily an expectation of marriage. This is a word of fairly recent origin, so its meaning isnt uniform in all areas. Note that while marido refers to a husband, there is no corresponding feminine form, marida, in standard use. Sample Sentences Referring to Family Members Here are some simple sample sentences you can use as models for your own: Mi padre es carpintero. (My father is a carpenter.)Mi tà ­a es dentista.(My aunt is a dentist.)Mi madre es ama de casa. (My mother is a housewife.)Tengo dos hermanos y una hermana. (I have two brothers and a sister.)Tengo cuatro hermanos. (This sentence can be seen as ambiguous by English speakers. It can be correctly translated as either I have four brothers or I have four siblings.)Tengo nueve tà ­os. (I have nine aunts and uncles or I have nine uncles.:)Mi madrastra vive en el estado de Nueva York. (My stepmother lives in New York state.)Mis sobrinas viven en Chicago. (My nieces live in Chicago.)Mi padre est muerto. (My father is dead.)Mi prima est muerta. (My female cousin is dead.)Mi madre est viva. (My mother is alive.)Otto y Edith Frank fueron los padres de Ana Frank. (Otto and Edith  Frank were the parents of Anne Frank.)Los primos no pueden casarse segà ºn nuestra cultura. (Cousins cannot marry accoridng to our culture.)Los suegras siempre tienen mala reputacià ³n. (Mo thers-in-law always have a bad reputation.)