Ions and Ionic Compounds

The nucleus of an atom is unchanged by chemical processes, but some atoms can readily gain or lose electrons. If electrons are removed from or added to an atom, a charged particle called an ion is formed. An ion with a positive charge is a cation (pronounced CAT-ion) a negatively charged ion is an anion (AN-ion). 

To see how ions form, consider the sodium atom, which has 11 protons and 11 electrons. This atom easily loses one electron. The resulting cation has 11 protons and 10 electrons, which means it has a net charge of 1 -I-. 

In general, metal atoms tend to lose electrons to form cations and nonmetal atoms tend to gain electrons to form anions. Thus, ionic compounds tend to be composed of metals bonded with nonmetals, as in NaCl. 

Give the chemical symbol, including superscript indicating mass number, for (a) the ion with 22 protons, 26 neutrons, and 19 electrons (b) the ion of sulfur that has 16 neutrons and 18 electrons. 

In general, we wiU focus on the net charges of ions and ignore their mass numbers unless the circumstances dictate that we specify a certain isotope. 

3 What is the correct formula for the compound carbon tetrachloride  

An atomic ion or monatomic ion is one that consists of just one atom with a positive or negative charge. The loss of one or more electrons from an atom yields a cation, an ion with a net positive charge. For example, a sodium atom (Na) can readily lose an electron to become a sodium cation, which is represented by Na  

An anion is an ion whose net charge is negative due to an increase in the number of electrons. A chlorine atom (Q), for instance, can gain an electron to become a chloride ion, Q  

Sodium chloride (NaCl), ordinary table salt, is called an ionic compound because it consists of cations (Na ) and anions (Cl ). 

An atom can lose or gain more than one electron. Examples include Fe , S, and 

A monatomic cation is named simply by adding the word ion to the name of the element. Thus, the ion of potassium (K ) is known as potassium ion. Similarly, the cations formed by the elements magnesium and aluminum (Mg and Al ) are called magnesium ion and aluminum ion, respectively. It is not necessary for the name to specify the charge on these ions because their charges are equal to their group numbers. 

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Refer to the "Ions and Ionic Compounds" chapter for more about naming ionic compounds. 

Atoms and Molecules 2-2 Chemical Formulas 2-3 Ions and Ionic Compounds 2-4 Names and Formulas of Some Ionic Compounds 2-5 Atomic Weights 2-6 The Mole... 

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