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The periodic table is organized in rows (periods) and columns (groups). Elements are placed in the periodic table according to their atomic number and their properties. Elements with similar properties are grouped together in columns.

Metals and nonmetals have different characteristics. Metals are generally shiny, good conductors of electricity and heat, malleable, and ductile. Nonmetals, on the other hand, are usually dull, poor conductors of electricity and heat, and brittle. There are also elements called metalloids, which have properties intermediate between metals and non-metals.

Looking at the periodic table, we see that metals are located on the left side and center of the table, while nonmetals are located on the right side. The metalloids are found along the line that separates metals and nonmetals.

As we move from left to right across the periodic table, the elements change from metals to metalloids (elements with properties in between those of metals and nonmetals) and then to nonmetals. This change in properties is due to the change in the balance between the attraction the nucleus has for the outer electrons and the repulsion between the outer electrons themselves. As we move across a period, the valence electrons are added to the same energy level and the nuclear charge increases. This results in increased attraction between the nucleus and the electrons. At the same time, the repulsion between the valence electrons also increases. The balance between these forces generally results in a gradual change in properties from metallic to nonmetallic or vice versa. In summary, the line that separates metals from nonmetals on the periodic table is diagonal downward to the right due to the gradual change in properties of elements as we move across the periodic table. Elements with intermediate properties between metals and nonmetals (metalloids) are found along this diagonal line, further emphasizing the gradual transition between these two types of elements.