Chemistry test History of Periodic Table and Ions

Dobereiner

A German chemist known for his work on the law of triads which foreshadows the periodic law.

Law of Triads

Proposed by Dobereiner; states that in a triad of elements, the atomic weight of the middle element is the average of the other two.

Dmitri Mendeleev

Considered the father of the periodic table; arranged elements by atomic mass and predicted properties of undiscovered elements.

Predicted New Elements

Mendeleev's method of leaving gaps in his periodic table to predict the existence and properties of undiscovered elements.

Henry Moseley

English physicist who redefined the periodic table based on atomic number rather than atomic mass.

Modern Periodic Table

A table arranged by atomic number, introduced by Henry Moseley, representing a more accurate reflection of element properties.

Periodic Law

The principle that elements, when arranged by increasing atomic number, demonstrate a periodic pattern in physical and chemical properties.

Hydrogen

An element that stands apart in the periodic table; it has one valence electron and behaves more like a nonmetal.

Cation

A positively charged ion formed when an atom loses one or more electrons.

Anion

A negatively charged ion formed when an atom gains one or more electrons.

Triads

Groups of three elements with similar properties, arranged by Dobereiner.

Atomic Mass

The mass of an element, used by Mendeleev to initially arrange the periodic table.

Groups

Vertical columns in the periodic table; elements in the same group have similar physical and chemical properties.

Periodic Pattern

The recurring trends in properties of elements as you move across or down the periodic table.

Valence Electron

The electron in the outermost shell of an atom that is involved in chemical reactions.

Predictive Gaps

Spaces left in Mendeleev's periodic table representing unknown elements based on existing properties.

Element Properties

Distinctive characteristics of elements, which form patterns used in organizing the periodic table.

Reactivity

The tendency of an element to engage in chemical reactions, influenced by its valence electrons.

Similar Properties

Characteristic shared among elements in the same triad or group that indicate related behavior in reactions.