4.2 Periodic Table and Element Discovery

Flashcards covering key concepts from the periodic table and element discovery.

Periodic Table

A tabular arrangement of the chemical elements, organized by increasing atomic number, that shows the periodic law.

Atomic Number

The number of protons in the nucleus of an atom; determines the chemical properties of the element.

Dmitri Mendeleev

Russian chemist who formulated the periodic law and created the first version of the periodic table in 1869.

Periodic Law

The observation that the physical and chemical properties of elements recur at regular intervals when arranged by atomic weight.

Group

A vertical column in the periodic table, containing elements with similar chemical properties.

Period

A horizontal row in the periodic table, where elements are arranged by increasing atomic mass or atomic number.

Isotope

Atoms of the same element that have different numbers of neutrons, resulting in different masses.

Metalloids

Elements that have properties of both metals and non-metals; found along the zig-zag line in the periodic table.

Alkali Metals

Group 1 elements that are highly reactive and form alkaline solutions when they react with water.

Noble Gases

Group 18 elements that are inert and do not readily react with other substances.

Relative Atomic Mass

The weighted average mass of an atom of an element, taking into account the relative abundances of its isotopes.

Eka-silicon

The name given by Mendeleev to the element germanium, before its discovery, predicting its properties.

Weight Comparison

Chemists compare equal numbers of atoms to measure and compare the masses of atoms due to their small size.

Transition Metals

Elements found in groups 3-12 of the periodic table; known for their ability to form various oxidation states.

Element Discovery

The process of identifying new chemical elements, often involving complex synthesis and experimental verification.

IUPAC

International Union of Pure and Applied Chemistry, responsible for naming chemical elements and compounds.