Chemistry Class 11: Periodic Table & Element Classification

Significant Features of the Periodic Table

• Displays elements in order of increasing atomic number, which defines their position.
• Organizes elements into rows (periods) and columns (groups) based on similar chemical properties.
• Groups contain elements with similar valence electron configurations, leading to predictable trends.

Periodicity of Elements

• Primarily based on the electron configuration of atoms, determining chemical and physical properties.
• The repetition of similar properties occurs at regular intervals as atomic numbers increase.

Groups Containing Only Metals

• Group 1 (alkali metals) and Group 2 (alkaline earth metals) exclusively contain metals.
• Transition metals, along with lanthanides and actinides, also comprise entirely metallic elements.

Trends Across Periods

• As you move from left to right across a period, the atomic radius decreases due to increased nuclear charge, pulling electrons closer.
• Ionization energy generally increases across a period, making it harder to remove an electron.

Characteristics of Metalloids

• Metalloids, such as silicon and germanium, possess a mix of metallic and non-metallic properties.
• A common characteristic disallowed for metalloids is being highly malleable like metals; they are typically brittle.