Development of the Periodic Table

the average mass of an atom of an element compared with carbon-12.

the number of protons in the nucleus of an atom.

arranging objects into groups based on shared characteristics.

a prefix used by Mendeleev meaning "one," indicating an undiscovered element one place below a known element.

the distribution of electrons around the nucleus of an atom.

(Ga) — the element that matched Mendeleev's predicted eka-aluminium.

(Ge) — the element that matched Mendeleev's predicted eka-silicon.

a vertical column of elements with similar chemical properties.

Newlands' observation that every eighth element had similar

an element that is typically shiny, conducts heat and electricity, and forms positive ions.