Covalent and Ionic Compounds

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Compounds are pure substances that contain atoms of two or more elements chemically combined in fixed ratios. In this lab, we observed two types of compounds, Ionic compounds and Covalent compounds. Ionic compounds are chemical compounds consisting of two or more ions that are held adjacent to each other by electrical attraction. “One of the ions, called an “anion,” has a negative charge, and the other is called a “cation,” and has a positive charge. “Cations” are usually metallic atoms and “anions” are either atoms of nonmetals or polyatomic ions. “ (1) A polyatomic ion is an ion that contains at least two atoms. A covalent compound is a compound in which the atoms that are bonded share at least one pair of valance electrons, the electrons that are located in the outermost shell of an atom, as opposed to transferring electrons from one atom to another. Covalent compounds are usually formed between nonmetal atoms.

While both Ionic and Covalent Compounds contain atoms of two or more elements chemically combined in fixed ratios, their physical properties differ considerately. For instance, Ionic compounds tend to be very hard, brittle solids at room temperature. Generally, when Ionic compounds are struck with a hard object, like a hammer, they shatter. “They break or shatter because their ions are arranged in a repeating three-dimensional pattern called a “crystal lattice.” Each ion in the lattice is bonded to the surrounding ions of the opposite charge.” (2) When the compound is hit, the ions move and the lattice’s pattern changes. Ions of like charge are forced closer and repel one another, which ultimately could cause the crystal to break or shatter. In comparison to Ionic compounds, Covalent compounds are soft and spongy. Covalent compounds form distinct molecules with atoms that are bound tightly to one another. However, unlike Ionic compounds, the molecules do not interact with each other very often, except through fairly weak forces called “intermolecular forces.” This allows the molecules to move around each other very easily, because no bonds are between them. As a result, Covalent compounds are fairly flexible and spongy. Generally at room temperature, Covalent compounds tend to be liquids or gases. According to tutorvista.com, however, “a few covalent compounds, such as sugar, exist as solids at room temperature.” Ionic compounds also have very high boiling and melting points because it takes a large amount of energy for all of the positive and negative charges, which make up the crystal lattices to get ripped apart from one another.

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