Compounds sodium chloride

A mixture contains two or more substances combined in such a way that each substance retains its chemical identity. When you shake copper sulfate with sand (Figure 1.4), the two substances do not react with one another. In contrast, when sodium is exposed to chlorine gas, a new compound, sodium chloride, is formed. 

But there is a second notion, which Mendeleev sometimes called "real dements," in order to indicate their more fundamental status. In Bis sense, Ihe eh emants represent abstract substances that lack what wc normally regard as properties and that represent the form that elements take when they occur in compounds. For example, sodium and chlorine as simple substances—a grey mrt.il and a gicmish gas respectively—are nol literally present in the compound sodium chloride (table salt). Mendeleev would have said Brat sodium and chlorine are present In the compound as the abstract or "real ctemanls. ... 

A solid that contains cations and anions in balanced whole-number ratios is called an ionic compound. Sodium chloride, commonly known as table salt, is a simple example. Sodium chloride can form through the vigorous chemical reaction of elemental sodium and elemental chlorine. The appearance and composition of these substances are very different, as Figure 2-24 shows. Sodium is a soft, silver-colored metal that is an array of Na atoms packed closely together. Chlorine is a faintly yellow-green toxic gas made up of diatomic, neutral CI2 molecules. When these two elements react, they form colorless ciystals of NaCl that contain Na and Cl" ions in a 1 1 ratio. 

UU compound. Sodium atoms and chlorine atoms, for example, bond to make the compound sodium chloride, commonly known as table salt. Nitrogen atoms and hydrogen atoms join to make the compound ammonia, a common household cleaner. 

A compound is represented by its chemical formula, in which the symbols for the elements are written together. The chemical formula for sodium chloride is NaCl and that for ammonia is NH3. Numerical subscripts indicate the ratio in which the atoms combine. By convention, the subscript 1 is understood and omitted. So the chemical formula NaCl tells us that in the compound sodium chloride there is one sodium for every one chlorine, and the chemical formula NH3 tells us that in the compound ammonia there is one nitrogen atom for every three hydrogen atoms, as Figure 2.12 shows. 

The compounds sodium chloride and ammonia are represented by their chemical formulas, NaCl and NH3. A chemical formula shows the ratio of atoms used to make the compound. 

I Sodium metal and chlorine gas react together to form sodium chloride. Although the compound sodium chloride is composed of sodium and chlorine, the physical and chemical properties of sodium chloride are very different from the physical and chemical properties of either sodium metal or chlorine gas. 

I pound. In pure gold, for example, there is nothing but the element gold. In pure table salt, there is nothing but the compound sodium chloride. If a material is impure, it is a mixture and contains two or more elements or compounds. This classification scheme is shown in Figure 2.20. 

A sodium ion and a chloride ion together make the chemical compound sodium chloride, commonly known as table salt. This and all other chemical compounds containing ions are referred to as ionic compounds. All ionic compounds are completely different from the elements from which they are made. 

An ionically bonded molecule (NaCl). (a) A sodium atom (Na) can donate the one electron in its valence shell to a chlorine atom (Cl), which has seven electrons in its outermost shell. The resulting ions (Na+ and CP) bond to form the compound sodium chloride (NaCl). The octet rule has been satisfied, (b) The ions that constitute NaCl form a regular crystalline structure in the solid state. 

The elements sodium and chlorine react together to form the compound sodium chloride, which has a giant ionic lattice structure. 

Elements in the first two groups of the periodic table are some of the most reactive elements known. In fact, many of the elements are so reactive that water, or in some cases air, can cause them to explode or catch fire. Although many of their names are familiar— sodium, potassium, and calcium, for instance—it is rare to find these elements on their own. Instead, these elements are usually combined with another more stable element to create a compound. Sodium chloride, or table salt, is a good example of a compound. 

The sodium atom donates its valence electron to the chlorine atom to form the ionic compound, sodium chloride. 

A word equation identifies the reactants and products of a chemical reaction by name. In Chapter 3, you learned that chlorine and sodium combine to form the ionic compound sodium chloride. This reaction can be represented by the following word equation ... 

In the compound sodium chloride, stability is achieved by loss and gain of electrons so that each has a complete outer electron shell (Figure 7.1). The negative ion, CP, is called an anion and the positive ion, Na+, a cation. 

The arrangement of sodium ions (l la+) and chloride ions (CP) in the ionic compound sodium chloride. 

Sodium cyanide inaqueous-alcoholic solution reacts energetically with chloropicrin to form various compounds sodium chloride, nitrite, carbonate and oxalate, cyanogen chloride, etc. ... 

Just look at what is produced one positive sodium ion and one negative chloride ion. In any real sample of sodium and chlorine, of course, there would be billions of ions, but for every one sodium ion there would be one chloride ion. They would attract each other because they have opposite charges to form a compound, sodium chloride. Its formula is NaCl because the ratio of sodium ions to chloride ions is 1 1. See also Section 2.3.1 for further details. 

One of the defining characteristics of single-replacement and combustion reactions is that they always involve the transfer of electrons from one atom to another. So do many, but not all, synthesis and decomposition reactions. For example, you studied the synthesis reaction in which sodium and chlorine react to form the ionic compound sodium chloride. 

Bond Formation The positive sodium ion and the negative chloride ion are strongly attracted to each other. This attraction, which holds the ions close together, is a type of chemical bond called an ionic bond. In Figure 13, sodium and chloride ions form an ionic bond. The compound sodium chloride, or table salt, is formed. A compound is a pure substance containing two or more elements that are chemically bonded. 

Dissolution of an ionically bonded compound, sodium chloride, by water molecules. 

What is the most popular food additive In most kitchens, the answer is salt. It is used in cooking and at the table to enhance the flavor of food. Chemists refer to it as sodium chloride. The chemical name tells you what elements make up the compound sodium chloride contains the elements sodium and chlorine. 

You know that when sodium and chlorine are mixed, a reaction occurs and a compound, sodium chloride, forms. The photograph at the beginning of this chapter showed the macroscopic view of this reaction. What can be happening at the atomic level Begin by picturing a collision between a sodium atom and a chlorine atom. Locate these atoms on the periodic table. Sodium is in Group 1, so it has one valence electron. Chlorine is in Group 17 and has seven valence electrons. 

Sodium, a dangerously reactive metal, reacts with chlorine, a poisonous gas, to form the stable compound sodium chloride, table salt. 

How is the compound sodium chloride different from the elements of which it is composed ... 

Objective 31 Figure 3.18 shows the solid structure of the ionic compound sodium chloride, NaCl. 

Many solids have highly ordered structures. An example is the ionic compound sodium chloride. If you turn to Figure 2.11, you will see that the Na and CP ions are arranged in a regnlar manner. This three-dimensional strnctnre is called a crystal lattice. Similar crystal lattices also exist in metals such as aluminum (Al) and iron (Fe). 

Figure 2.ID depicts a mixture, a group of two or more substances (elements and/or compounds) that are physically intermingled. In contrast to a compound, the components of a mixture can vary in their parts by mass. Because its composition is not fixed, a mixture is not a substance. A mixture of the two compounds sodium chloride and water, for example, can have many different parts by mass of salt to water. At the atomic scale, a mixture is merely a group of the individual units that make up its component elements and/or compounds. Therefore, a mixture retains many of the properties of its components. Saltwater, for instance, is colorless like water and tastes salty like sodium chloride. Unlike compounds, mixtures can be separated into their components by physical changes chemical changes are not needed. For example, the water in saltwater can be boiled off, a physical process that leaves behind the sodium chloride.

These ions with their opposite charges attract each other in the same way as do the simple ions in binary ionic compounds. However, the individual polyatomic ions are held together by covalent bonds, with all of the atoms behaving as a unit. For example, in the ammonium ion, NH +, there are four N—H covalent bonds. Likewise, the nitrate ion, N03, contains three covalent N—O bonds. Thus, although ammonium nitrate is an ionic compound because it contains the NH " and N03 ions, it also contains covalent bonds in the individual polyatomic ions. When ammonium nitrate is dissolved in water, it behaves as a strong electrolyte like the binary ionic compounds sodium chloride and potassium bromide. As we saw in Chapter 8, this occurs because when an ionic solid dissolves, the ions are freed to move independently and can conduct an electric current. 

---