As in DNA replication, RNA is synthesized in the 5' â 3' direction (from the point of view of the growing RNA transcript). Only one of the two DNA strands is transcribed. This strand is called the template strand, because it provides the template for ordering the sequence of nucleotides in an RNA transcript.
The properties of the chemical elements are summarized on the periodic table, which organizes the elements by increasing atomic number into rows (periods) in which the columns (groups) share recurring (periodic) physical and chemical properties.
The modern periodic table is a chart containing the elements arranged in order of increasing atomic number. A vertical column, called a group, contains elements with similar properties. A horizontal row is called a period. The atomic number of the elements in a period increases from left to right along the row. Before the development of the modern periodic table, there were other attempts to arrange the elements in a useful way. For example, DÃ¶bereiner arranged groups of three elements with similar properties into âtriads'. Newlands and Mendeleev arranged the elements in order of increasing relative atomic mass.