Mixture and a Compound - Lab Report Example

Mixture and a Compound al Affiliation This document contains elaborative differences between mixtures and compounds through their properties and formation, the variation of components that make them distinctive and how their components can be separated. It also describes how to differentiate an element and a compound despite being pure substances by results from decomposition. In the paper the metals, non-metals, and transitional elements are discussed to demonstrate the bonds. Ionic bonding formed between metals and non metals are explained and illustrated. Explanation following electrons transfer between the donor and receptor atoms that form cations and anions is also given. Documentation of covalent bonds, their formation details and types, polar and non polar, covalent bonds are briefly mentioned with some examples given. It also expresses how covalent bonds form between atoms of a molecule in a single and from different elements. Keywords: Mixtures, Compound, Element, Substance, Cation, Anion, Atoms, Molecules, Bonding, Covalent Bonds, Ionic Bond, Shared Electrons, Electron, Properties A mixture is a matter of impure substances made of either two or more homogenous pure substances (compounds or elements), brought together physically (Syamal, 2007). The components inside a mixture at a single moment vary relatively; hence, they are not fixed. The key properties of mixtures are that they don’t have fixed properties and that no new substance is formed in the combination; reason being that their property is dependent on combination fraction and nature of the constituents where properties of constituents are similar to those of the mixture. Just as it is formed, its constituents can also be split by physical methods like sedimentation, decantation, distillation and chromatography among others. On the contrary, compounds are pure substances, consisting of two or more components, just like mixtures, but chemically merged together to create a new substance with different properties from its constituents. At any single moment the components of a compound exist in fixed ratios. They have fixed properties without having to rely on constituents’ properties. Its constituents can be split through chemical reactions and not physical methods. Components of a compound are held together by strong covalent bonds unlike in mixtures, whose components are held loosely by weak forces. Elements and compounds are pure substances, but unlike compounds, elements cannot be split further. According to Stoker ( 2012, p.16) “a pure substance can be classified as either an element or a compound on the basis of whether it can be broken down into two or more simpler substances by chemical means.” In the event where compounds are heated or broken down, it produces simpler substances that had been used to create it. An element consists of atoms of a homogeneous type that are kept close together by bonds. There exist a hundred and seventeen recognized elements where less than thirty of them, have been developed in the laboratory by bombard smaller units with naturally occurring elements. However, they are radioactive and can easily revert back into their natural existing elements. When a pure substance is broken down, and there exist presence of hetero-atomic molecules, then the substance is a compound since the atoms are different indicating presence of different elements. Elements contain mono-atomic molecules. In chemistry, litmus papers have been used to test the presence of acids and bases which are compounds. While reviewing a sample, qualitative analysis reveals whether it is an element or a compound present in the sample. Examples are electrophoresis used in DNA pattern identification, chemical tests and X Ray Crystallography. Ionic bonds forms mostly between metals and non metals (cations that are positively charged and anions that hold a negative charge). Metals will always react to loose free electrons in the outer shell while non metals gain them. These types of bonds are very strong being supported by electrostatic energy that make ions of unlike charges to attract. Consider an example of sodium and fluorine combination, (Na+ + F- = NaF). The outermost shell of sodium atom has one electron while Fluorine has seven, one less to complete the octet. In the event when sodium gives out an electron to fluorine, sodium and fluorine changes into ions (Na+ and F- respectively). The electrostatic attraction between the two is the ionic bond, and the compound formed is an ionic compound. At room temperature they exist in solid state and both the boiling and melting points are high. They are non-directional, have high polarity and take no definite shape. Covalent bonds occur in the reaction of non metals. Non metals react by gaining electrons in the event of ionic bonding. However, when dealing with in the absence of metals, nonmetals react by sharing the all or some of the outermost electrons of their shells. Referring to Henrickson (2005, p.265), “a covalent bond is a pair of electrons shared by two atoms….provides a second way for atoms to acquire an octet of electrons in their valence shell.” The force of attraction in this case appear due to the shared electrons but a shift from one single atom to another. They are directional in nature, existing in liquid or gaseous state at room temperature, with low polarity, boiling and melting point. Covalent bonds have a specific shape. Formation of ionic compounds: Metals in a periodical table of chemical elements occupy group 1 and 2(Alkali metals and alkaline earth metals) with an exception of the first element, Hydrogen since it does not support most features of metals. Other elements that exhibit partial properties of metals are metalloids; they border the non-metal in the periodic table. Groups 3 through 11, the lanthanides and actinides of transition elements are also metals which have a partially filled d subshell (“characterizing the elements,” 2010-2011). Metals are known to have high capacity to conduct heat and energy. Non metals consist of “the elements H, B, C, N, O, F, Si, P, S, Cl, As, Se, Br, Te, I, and At” (“characterizing the elements,” 2010-2011) occupying the right hand side of the periodic table. When metals react with non metals, the metals provide extra electrons of their outermost shell to the non metals whose outermost shell are incomplete. The move of the electron from a metal and reception of the electron by non metals keeps the atoms stable. Metals become positively charged cations and nonmetals, negatively charged anions. For an ionic bond to be formed, at least one electron donor and acceptor should be available. In the state of an ionic bond, the charge of the compound should be neutral (zero). Ionic compound chemical formulas are expressed in the ration of cations to anions; here the metals are given priority over non metals. The number of electrons that metals loose and non metals gain depends on which group in the periodic table they come from. All elements in group 1 react by loosing 1 electron while in group 2, they loose 2. Non metals like group 17 react with metals to gain an extra electron to be stable. The examples of two sets of chemical reactions that form ionic compounds are shown below. Sodium + Chlorine = Sodium chloride. Sodium (Na) looses an electron to form positively charged Sodium cations ( Na+) while Chlorine (Cl) gains the electron to form negatively charged anion (Cl-). Na+ + Cl- = Na+ Cl- The net charges are neutralized to zero in the formed ionic compound of Sodium chloride (NaCl).When Calcium reacts with Chlorine, it produces two of its extra electrons which have to be neutralized by two atoms of Chlorine, to from calcium chloride (CaCl2). Ca2+ + Cl- + Cl- = Cl- + Ca2+ + Cl- =CaCl2 Formation of covalent bonds: when non metals react with each other, they tend to share electrons to be stable. According to Dlarsen (2010), covalent bonds are most likely to occur if molecules have alike electronegativity, (same affinity for electrons) therefore, both atoms will donate and share electrons in order to achieve octet configuration that keep them firm. Non metals convey heat and electricity poorly. There are elements that exist naturally as diatomic molecules in the periodic table. The identical atoms in the molecules are connected together by covalent bonds. Fluorine (F2), Chlorine (Cl2), Iodine (I2) and bromine (Br2) all from group 17 members exist in such state among other non metals. Covalent bonds come in two forms; polar covalent bonding that facilitate dissimilar share of bonding pair, and non polar covalent bonds that support equivalent share of bonding pair. An example is of non polar covalent bond exist in Hydrogen (H2). H - H = H2 Hydrogen atom has only a single electron on the outer most shell; therefore, in order to achieve the octet configuration, it has to share its outer most electron with another Hydrogen atom so as to form (H2) hydrogen molecule. For polar covalent bond, different atoms are form the bond; an example is a reaction between hydrogen and Fluorine to obtain hydrogen fluoride (HF). H + ƃ + F-ƃ = HF Hydrogen releases is electron to be shared because it is less electronegative than Fluorine. Fluorine atom takes a partial negative charge as Hydrogen atom takes a partial negative charge. Other types of bonds exist; single, triple and even double covalent bonds. Oxygen molecule (O2) has a double covalent bond where to exist as a molecule, each atom has to share two of its six outermost electrons to be stable. It is represented in the following way by two bonds. O ═ O The double lines illustrate that each oxygen atom produces two of its outermost electrons to be shared. O ═ O Reference List “Characterizing the Elements.” (2010-11). Los Alamos National Laboratory. Retrieved October 31, 2012 from http://periodic.lanl.gov/metal.shtml Ionic and Covalent Bond. (2010, July 17). UC Davis ChemWiki. Retrieved from http://chemwiki.ucdavis.edu/Organic_Chemistry/Fundamentals/Ionic_and_Covalent_Bonds Henrickson, Ch. (2005 ). CliffsStudySolver Chemistry. Hoboken: Wiley & Sons, Incorporated, John. Stoker, H. S. (2012 ). General, Organic, And Biological Chemistry. Belmont, CA: Brooks/Cole publishers. Syamal, A. (2007). Living Science Chemistry 9. Mumbai: Ratna Sagar P. Ltd. Read More