The periodic table: the map of elements

Everything is built from ~118 elements — like words from letters. Mendeleev arranged them in a table: rows are periods, columns groups with similar character. Noble gases on the right are lazy and react with no one; metals on the left give electrons and flare up. The atomic number equals the proton count.

• ●H (1) — hydrogen, the lightest
• ●Fe (26) — iron, Au (79) — gold
• ●Groups are families: Li, Na, K — all reactive metals