16Apr 2019 by Vincent Summers 2 Comments

Which are Stronger? Covalent or Ionic Bonds?

Chemistry, Physics
Almost all the atoms found in nature, left alone to themselves, are stable structures. If they always remained such, there would be no need of chemists. Fortunately, when in close contact, atoms can react in a number of ways. Often they link to each other in various combinations through bonding, forming molecules called compounds. Such interaction requires explanation, and so provides employment to humans educated in this field: The field called chemistry. Chemical Bonds: Ionic and Covalent There are a variety of ways atoms bond to one another. Some bonds are weaker, and some are stronger. Two of the strongest forms of chemical bond are the ionic and the covalent bonds. Chemical bonds form between two atoms, each with its own electron environment. If each of the two atoms shares…
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16Nov 2014 by Vincent Summers 1 Comment

The Zwitterion – Nature, Occurrence, Ongoing Research

Chemistry
What in the world is a zwitterion? What is its importance? Molecules are bonded atoms that act as a unit. They are electrically balanced. This means they contain a total number of electrons equal to the number of protons. If a chemical structure does not possess an equal number of electrons and protons it is an ion. Molecules as a unit are electrically neutral. However, there may be local charges due to geometry or electronegativity. These charges are mostly less than that of a proton or electron. There is an exception. It is the zwitterion. This kind of ion has a full positive and a full negative charge. In organic chemistry there may be an alkyl backbone consisting of carbon (C) and hydrogen (H). Other groups (pendant groups) include hydroxyl,…
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07Nov 2014 by Vincent Summers 4 Comments

What is a Hydronium Ion?

Chemistry
What is a hydronium ion? Water... Is there a more important or abundant liquid on the face of the earth? It possesses an amazing number of properties. It is essential to our very existence. Water is one of an extremely small number of substances (liquid ammonia is another) that expands and becomes lighter on freezing. Ice floats and forms an insulating, protective crust over underlying water. If ice sank rather and didn't float instead, the ponds and lakes of earth would completely freeze. All living things would die. Structure & Electrical Properties of Water Water's chemical formula is H2O. Occasionally it is written HOH or H–O–H. This way of writing the structure is convenient as long as one is aware of the shortcomings. Water is not a linear molecule. It…
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20Aug 2014 by Vincent Summers 6 Comments

Cesium Auride – Relativistic Electrons?

Chemistry
[caption id="attachment_7305" align="alignright" width="440"] Imagine relativistic electrons.[/caption] Strange isn't the word for cesium auride. Gold in liquid form? Indeed, yes! Discovered more than a half century ago, the properties of this cesium and gold compound are not yet fully understood. There are all sorts of curios in chemistry. Chemists love them dearly. I still remember one particularly strange molecule. It was affectionately named hexamethyl bathroom tile. Free Lectures Recently I listened to some free online chemistry lectures. They were produced by MIT under its OpenCourseWare program. One of those lectures spoke of an alloy of cesium and gold that acts like a salt, cesium auride. Key to its forming is the difference in electronegativity between cesium and gold. It is roughly the same as the difference between sodium and iodine!…
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28Oct 2013 by Vincent Summers No Comments

Silicon Tetrachloride Acts Like a Strongly Electronegative Atom

Chemistry
[caption id="attachment_5121" align="alignright" width="440"] Silicon Tetrachloride Molecule[/caption] The empirical formula of the compound silicon tetrachloride is SiCl₄. The molecule possesses tetrahedral symmetry. This means the atom of silicon is located at the center and the four atoms of chlorine are located at the four corners of a tetrahedron. Each chlorine atom is strongly electronegative, so the molecule of SiCl₄ strongly draws electrons. The core, silicon atom is insignificantly electronegative. Elemental Electronegativity Electronegativity is the tendency of an atom or other particle to attract electrons. It is high when an atom is small and outer electrons are least shielded from the positive nucleus. This makes fluorine the most electronegative of elements. Conversely, the alkali metal astatine, is least electronegative. Chlorine, while not so much so as fluorine, is still very electronegative.…
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26Feb 2013 by Vincent Summers 1 Comment

On the Nature of the Chemical Bond

Chemistry
[caption id="attachment_3393" align="alignright" width="440"] Proline - Ball and Stick Model CCA 2.5 by Peter Murray-Rust.[/caption] Atoms combine to form molecules. Atom A approaches atom B and cohesively attaches to it. Molecule AB is held together by a chemical bond.¹ That bond is written A–B,  or in the case of multiple bonds, A=B, A≡B, etc. Factors in Bond Formation The primary bonding agency is electrostatic force. This is the force between electrical charges. A positive charge is due to a lack of one or more electrons, producing cations. A negative charge is due to an excess of electrons, producing anions. One of the simplest examples is the formation from sodium (Na) and chlorine (Cl) of ordinary table salt, sodium chloride (NaCl).² We write, Na – e⁻ → Na⁺ Cl + e⁻…
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