Chemical Bonds

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Chemical Bonds
I. Introduction
Chemical compounds are formed by the joining of two or more atoms. A stable compound occurs when the total energy of the combination has lower energy than the separated atoms. The bound state implies a net attractive force between the atoms called a chemical bond. The two extreme cases of chemical bonds are the covalent bonds and ionic bonds. Covalent bonds are bonds in which one or more pairs of electrons are shared by two atoms. Covalent bonds, in which the sharing of the electron pair is unequal, with the electrons spending more time around the more non-metallic atom, are called polar covalent bonds. In such a bond there is a charge separation with one atom being slightly more positive and the other more negative, i.e., the bond will produce a dipole moment. On the other hand, Ionic bonds are bonds in which one or more electrons from one atom are removed and attached to another atom, resulting in positive and negative ions which attract each other. In the extreme case where one or more atoms lose electrons and other atoms gain them in order to produce a noble gas electron configuration, the bond is called an ionic bond. Covalent bonding is a form of chemical bonding between two non-metallic atoms which is characterized by the sharing of pairs of electrons between atoms and other covalent bonds. Ionic bond, also known as electrovalent bond is a type of bond formed from the electrostatic attraction between oppositely charged ions in a chemical compound. These kinds of bonds occur mainly between a metallic and a non-metallic atom. In Chemical Bonds, the principle “like dissolves like” is always abided.

To verify the above concept, an experiment was conducted with the following objectives: (1) identify ionic and covalent compounds based on certain physical properties, (2) differentiate between: a. covalent and ionic bonds b. nonpolar and ionic compounds c. polar and nonpolar compounds, (3) enumerate a few properties of: a. ionic compounds b. polar compounds c. nonpolar compounds, (4) explain why some compounds dissolve in water but others don’t, (5) predict the type of bond that may be present in an aggregate of atoms, given a set of properties.

II. Chemicals/ Reagents needed
The chemicals and reagents used in the experiment are as follows: cupric chloride crystals (CuCl2), distilled water (H2O), kerosene, cooking oil, salt (NaCl) solution, alcohol, Salt (NaCl), and sugar. The apparatus used include test tubes, and two softdrink caps (tansan).

III. Procedure
1. Solubility
1.0 mL of water was placed in a test tube and 1.0 mL of kerosene in another test tube. After that, a piece of cupric chloride crystals was added in the two test tubes. Then it was shaken and we recorded the observed results.

Afterwards, we then repeated the above procedure using cooking oil instead of cupric chloride crystals. And again, we recorded the observed results.
2. Relative boiling point
We placed 5.0 mL of water in a test tube, NaCl solution in the second test tube, and alcohol in the third test tube. Then we heated the three test tubes simultaneously. And then, we recorded the time until boiling occurred.

3. Relative Melting Point
First we placed a pinch of salt (NaCl) crystals in a softdrink cap (tansan) and about the same amount of sugar in another cap. Then we heated the two caps simultaneously on an alcohol lamp and we recorded the time for each solid to melt.

IV. Observation
The results of the experiments for solubility, relative boiling point, and relative melting point are summarized in the tables below. A. Solubility
Test Tube| Substance Used| Description of the resulting mixture| Type of Primary Bond| | Solute| Solvent| | Solute| Solvent|
1| CuCl2| H2O| Soluble| Ionic| Polar |
2| CuCl2| kerosene| Insoluble| Ionic| Non-polar|
3| Cooking Oil| H2O| Immiscible| Non-polar| Polar|
4| Cooking Oil| kerosene|...
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