Chemistry · Ch 7 — Modern Periodic Table
Structure of the Modern Periodic Table
Structure of the Modern Periodic Table
Although many scientists have proposed different layouts for the periodic table over the years, the 'long form' or 'modern periodic table' — a revised version of Mendeleev's original table built around the modern periodic law — remains the most convenient and widely-used form today. It consists of horizontal rows, called PERIODS (Mendeleev originally called them series), crossing vertical columns, called GROUPS, and the boxes formed at each row-column intersection hold individual elements. There are seven periods, numbered 1 to 7, and eighteen groups, numbered 1 to 18 — this 1-18 group numbering is the scheme recommended by the International Union of Pure and Applied Chemistry (IUPAC). Below the main grid sit two additional rows of fourteen elements each (the lanthanoid and actinoid series), giving a grand total of 118 boxes. As of today all 118 boxes are occupied, the later ones filled by artificially (manmade) synthesised elements, and IUPAC has approved an official name and symbol for every one of the 118 elements. Looked at as a whole shape, the table divides into four blocks: the two left-hand groups form the s- …
What this figure shows. The full 18-column x 7-row grid of the modern periodic table: each of the 118 element boxes sits at the intersection of its period (row 1 at top through row 7 at bottom) and its IUPAC group (column 1 on the left through column 18 on the right). Two extra rows of 14 boxes each — the lanthanoid series and the actinoid series — are drawn detached below the main grid, conventionally linked back to their slot in group 3 of periods 6 and 7 respectively. Superimposed on the grid, the table is shaded into four regions: the two left-hand columns (groups 1-2) form the s-block, the ten central columns (groups 3-12) form the d-block, the six right-hand columns (groups 13-18) form the p-block, and the two detached bottom rows form the f-block. A zig-zag 'staircase' line runs through the p-block separating meta …