Would you like please writing introduction and conclusion for this lab with clea
ID: 546936 • Letter: W
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Would you like please writing introduction and conclusion for this lab with clear hand writing? Thank you Mus EXPERIMENT Molecular Models18 and Chemical Bonds OBJECTIVES To construct models of molecules with single, double, and triple bonds. . To draw the structural formula for a molecule based on the molecular model. . To draw the electron dot formula corresponding to the structural formula. . To draw the structural and electron dot formulas for unknown molecular models. DISCUSSIONW The attraction between two atoms in a molecule is called a chemical bond. In a covalent bond, two nonmetal atoms are attracted to each other by sharing valence electrons. The valence electrons are The number of valence electrons is found from the element indicates the rn and has seven valence electrons (7e-). the electrons farthest from the nucleus and occupy the highest s and p sublevels. periodic table. The group number of an umber of valence electrons. For example, fuorine is in Group VIIA/17 Eample Exercise 18.1 Valence Electrons and the Periodie Table Refer to the group number in the periodic table and determine the the following elements: (a) H: (b) C and (c) O. Hydrogen is in group IA/1; thus, H has one Carbon is in Group IVA/14; thus, C has four valence electrons. (a) valence electron Solution: is in Group VILA/17; thus, CI has seven valence electrons.Explanation / Answer
The properties of chemical compounds are directly related to the ways in which atoms are bonded together into molecules. Chapter 2 in Chemistry in Context presents the basic ideas of chemical bonding, while Chapter 3 shows how the 3-dimensional shapes of molecules are related to the bonding. In this exercise, you will have the opportunity to apply your knowledge from those two chapters by constructing simple ball-and stick models for some common molecules. The models should help your understanding of electron arrangements in molecules and the resulting shapes of the molecules. You will investigate a number of small molecules containing carbon, nitrogen, oxygen and hydrogen, as well as a few molecules containing fluorine, chlorine, or sulfur. These are mostly substances that are important in the atmosphere and in polluted air, as discussed in Chapters 1, 2, and 3 of Chemistry in Context. In the process of doing this exercise you will see how “models” become very useful to chemists in understanding and predicting chemical properties.
BACKGROUND INFORMATION: ELECTRONS AND MOLECULES
The existence of chemical compounds with fixed composition implies that the atoms in compounds must be connected in characteristic patterns. Early models showed the atoms hooked together like links on a chain. Modern representations are a good deal more abstract and often mathematical in nature. Nevertheless, it is possible to represent molecular structures with reasonable accuracy by using relatively simple models. The models serve as a three-dimensional representation of an abstract idea. Molecular model building has proven so useful that it is rare to find a chemist who does not have a model kit close at hand.
The chemical bonds that hold atoms together in molecules generally consist of pairs of electrons shared between two atoms. Atoms tend to share outer electrons in such a way that each atom in the union has a share in an octet of electrons in its outermost shell. This generalization has come to be known as the octet rule. (You should review the discussion of Lewis structures and the octet rule) . The location of each element in the Periodic Table provides information about the number of electrons in the outermost level of the atoms. Carbon, for example, is in Group 4A and has four outer electrons; thus, it must share four additional electrons from other atoms to achieve a share in eight outer electrons (an octet). Oxygen, in Group 6A, has six outer electrons and shares two electrons from other atoms to achieve an octet. Hydrogen is a special case, needing to share is one electron with only one electron from another atom to achieve the stable outer electron configuration of the non-reactive element helium (He).
A single bond consists of one shared pair of electrons; a double bond is two shared pairs (i.e., 4 electrons), and a triple bond is three shared pairs (6 electrons). On paper the bonds are represented by single, double, or triple lines, respectively (-, =, ). In model kits, straight sticks represent single bonds, while pairs or triplets of curved sticks or springs represent double and triple bonds. Electrons not involved in bonding are termed unshared electrons.
An important part of this exercise involves identifying the 3-dimensional shapes of molecules. Molecules have certain shapes depending on their component atoms and the ways in which they are bonded to each other. The important shapes encountered in this exercise are linear, bent, triangular, pyramidal, or tetrahedral. Several factors contribute to determining molecular shape: (1) Electron pairs (both shared and unshared) try to keep as far away from each other as possible, while still remaining “attached” to atoms. (After all, they are all negatively charged and electrical charges of the same type will repel each other.) (2) Electron pairs tend to be symmetrically arranged around each atom in a 3-dimensiional manner. (3) Electron pairs not involved in the bonding (“unshared pairs” or “lone pairs”) are as important as bonding electron pairs (shared pairs) in determining the overall molecular shape and arrangement of atoms.
Conclusions: after completing this lab you will able to know
1. The tetrahedral shape is one of the most fundamental shapes in chemical compounds. How would you describe it in words to someone who has not seen it?
2. The “octet” rule appears to be a very important rule governing the structures of molecules. In light of your work with models, provide a simple explanation for the importance of 8 electrons.
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