Mendeleev

Dmitri Mendeleev

Russian chemist who created the periodic table by arranging elements based on increasing atomic weight and similar chemical properties

Prediction of Germanium

Mendeleev predicted the existence of Germanium by estimating its properties based on the blank space under silicon and above tin.

Significance of blank spaces in Mendeleev's table

The blank spaces indicated that there were undiscovered elements, showing that the table represented a law of nature rather than a random list.

Method of organizing the periodic table

Mendeleev organized the periodic table by arranging elements into rows based on increasing atomic weight and grouping similar chemical properties into columns.

Use of element cards by Mendeleev

Mendeleev used cards with element properties and rearranged them like a puzzle to find patterns in the periodic table.

Antoine Lavoisier

French chemist who in 1789 produced a list of 33 ‘simple substances’ categorized into gases, metals, non-metals, and earths, and discovered oxygen and hydrogen.

Telluric helix

A geometric periodic system created by Chancourtois in 1862, arranging elements by atomic weight in a spiral, showing that elements with similar properties align at the top or bottom of each other.

John Newlands' laws of octaves

A classification system introduced in 1865 that arranged 62 known elements into eight groups, noting that every eighth element has similar chemical properties, establishing a periodic law.