Tuesday, December 27, 2011

compounds can be molecular or ionic

The compounds can be molecular or ionic

Substances can be classified as molecular compounds or ionic compounds.

(. Pronounce "eye'-ons") are ionic compounds composed of ions Ions are atoms or molecules that have a global charge: positively charged ions are called cations (pronounced "Eye-cat'-ons") and negatively charged ions are called anions (pronounced "an eyes-ons"). A molecule that carries a positive or negative overall charge is called a polyatomic ion. Ionic compounds can be recognized as compounds formed by a metal attached to a nonmetal or polyatomic ion containing compounds.

Molecular compounds are those that contain only non-metals are glued together, and where there are polyatomic ions are present.

CaCl2 is an ionic compound containing a metal and attached to a metal does not.

NH4NO3 is an ionic compound because it contains at least one polyatomic ion. (More information about polyatomic ions later ...)

NH3 and H2O would be molecular compounds that contain only nonmetals bonded together and there are polyatomic ions.

The smallest unit of a molecular compound is a molecule. In an ionic compound, there is no molecule units, but there is a matrix or network of repeating units of cations and anions, which we call a "unit of the formula."

Writing formulas for binary ionic compounds

Binary ionic compounds, as its name suggests, consists of two elements. How to write the correct formula for ionic compounds formed between a metal and non metal? There are three steps, you will remember them by practicing how to write formulas.

1. Insert a symbol of the cation, then the symbol of an anion. And 'ionic compound formed between magnesium and chlorine, writes Mg 2 Cl-1.

2. Cruz taxes and the load on the cation becomes the index for the anion and the charge for the anion becomes the subscript for the cation. Thus in the example of magnesium chloride, can be written MgCl 2 -1. Place the positive and negative signs. For magnesium chloride, the formula would MgCl2. (If the index is 1, not written.)

3. Reduce and simplify so that the rates are the lowest of integers. For example, the ionic compound formed between calcium and sulfur, Ca +2 and S-2   Ca2S2 CaS.

4. Even if an ionic compound is composed of charged particles, should be combined so that the compound has a net charge of zero, so that the compound is neutral.


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