sentences: chlorine is a kind of element & sodium is a kind of element ->  sodium and chlorine are two elements  sodium and chlorine are two elements & sodium chloride is made of chlorine and sodium chemically combined ->  sodium chloride is made of two elements chlorine and sodium chemically combined  sodium chloride is made of two elements chlorine and sodium chemically combined & chemical bonds are formed by chemically combining elements ->  chemical bonds are formed in sodium and chlorine elements  chemical bonds are formed in sodium and chlorine elements & an element is made of one kind of atoms -> chemical bonds are formed among sodium atom and chlorine atoms