Basic Chemical Bonds, A Scientific Inquiry
Covalent, Ionic, and Hydrogen Bonds Make Chemistry and Life Possible
Aug 13, 2009
The chemical bond universe is fascinating. Dr. Linus Pauling won a Nobel Prize for his treatise on "The Nature of the Chemical Bond" which clarified chemical linkages of atoms. Chemical bonds can be made — or broken.
Matter, Elements and Atoms, Ten Useful Basic Chemistry and Chemical Definitions
A few definitions serve this discussion of basic bond chemistry.
- Matter, anything that occupies space and has weight. Anything real and demonstrable.
- Element, one of the basic 92 kinds of matter. Examples: oxygen, hydrogen, nitrogen, carbon.
- Atom, a small, single, unitary piece of matter with a nucleus and at least 1 proton (hydrogen), and electron(s). Atoms of elements heavier than hydrogen also have 1 or more neutrons in their nuclei. An atom is the smallest part of an element that maintains the properties of that element.
- Compound, two or more atoms chemically bonded to make a unique substance or type of matter. Examples: table salt= NaCl; Water= H2O.
- Chemical Bond, electronic or other forces that hold 2 or more atoms together in compounds. Examples: H2O = water, oxygen gas = O2.
- Solvent, a liquid into which matter can dissolve and completely disappear within. E.g. water, alcohol, acteone.
- Solute, compounds that can dissolve in a solvent. Examples: sugar and salt can each dissolve in water.
- Solution, the result of a solute dissolving in a solvent.
- Suspension, a solvent with floating, undissolved matter. Examples: tiny soil particles in water.
- Chemical reaction, a change, in the relationship of atoms, that causes atoms to chemically interact and form new relationships. HCl (acid) + NaOH (base)---> NaCl (salt) + HOH (water).
The Three Basic Bonds — Ionic, Covalent, Hydrogen
The three basic bonds are ionic, covalent and hydrogen.
Ionic bonds are common to almost all inorganic compounds such as salts, inorganic acids and bases. One element donates an electron to another element which receives the electron. The resulting union is an ionic compound. NaCl, HCl, and NaOH are simple examples. Bond strengths are modest.
Covalent bonds occur when two or more atoms share their electrons. These bonds are typical of organic compounds (carbon compounds) and some inorganic compounds. Carbon dioxide, methane and sugar are covalently bonded. Covalent bonds are the strongest bonds.
Hydrogen bonds are the attraction of hydrogen, and its proton positive nucleus, for electronegative atoms like oxygen. (double click the last two photos below to see this). Hydrogen bonds are the weakest of the three bonds and are easily broken. Nevertheless, in DNA opposing chains are attracted and bonded by thousands of these bonds giving an overall strong bond. Water molecules show inter-molecular hydrogen bonding.
A Simple Test for Ionic and Covalent Bonding
Superficially, salt and sugar seem alike. Both are white crystals in their dry, powdered forms, but they are so very different. If a teaspoon of sugar or salt, is added to a small glass of warm water and stirred, the crystals all dissolve and disappear to form solutions — a sugar solution and a salt solution. The water is the solvent and the added crystals are the solute.
How are these solutions similar, and how are they different? A simple experiment on solution conductivity is relevant. If two wires, connected to a small battery and bulb, are inserted into salt water the bulb lights up! When the wires are inserted into the sugar solutions, the bulb does not light up. The same results are obtained each time the wires are switched between solutions. Ionic bonded compounds when placed in water typically ionize. They form charged particles that promote the movement of electrons in water. The water becomes a great conductor of electrons and this called an electrolyte or ionized solution.
See more about atoms and the Periodic Table of elements.
Sources
Hill, J.W. and D.K. Kolb. 1995. Chemistry for Changing Times. Prentice-Hall Inc., Engelwood Cliffs, N.J.
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