Periodic Trends - Video Notes (Mendeleev, Periodic Law, and Classification)

Vocabulary flashcards covering key concepts from the Periodic Trends notes.

Periodic Trends

Patterns in element properties across periods and groups in the periodic table; reflect periodicity of chemical behavior.

Periodic Law

Properties of elements are periodic functions of their atomic numbers; historically ordered by increasing atomic mass.

Dmitri Mendeleev

Russian chemist who proposed the periodic table in 1869 and predicted the existence of undiscovered elements.

Prediction of Elements (Mendeleev)

Leaving gaps in the table to predict properties and existence of unknown elements.

Metals

Elements that are shiny, malleable, and good conductors of heat and electricity.

Nonmetals

Elements that are dull and poor conductors of heat and electricity.

Metalloids

Elements with properties intermediate between metals and nonmetals; often semiconductors.

Hydrogen

A nonmetal with properties similar to elements in both Group 1 and Group 17.

Atomic Mass

The average mass of an element's atoms; used historically to order elements in early periodic tables.

Atomic Number

The number of protons in an atom's nucleus; determines identity and modern placement in the periodic table.

Group 1 (Alkali Metals)

A column of highly reactive metals that form hydrides with hydrogen and share similar properties.

Group 2 (Alkaline Earth Metals)

A column of reactive metals that form hydrides with hydrogen and share similar properties.