Understanding the Periodic Table

Metals: Good conductors of heat and electricity, usually shiny, malleable, and found on the left side of the table.

Nonmetals: Poor conductors, often gases or brittle solids, located on the right side.

Metalloids: Have properties of both metals and nonmetals. Found along the zig-zag line between metals and nonmetals.

Groups: Vertical columns. Elements in the same group share similar chemical properties and number of valence electrons.

Periods: Horizontal rows. Elements in the same period have the same number of electron shells, but different properties.

Alkali Metals (Group 1): Highly reactive metals, soft, and shiny.

Alkaline Earth Metals (Group 2): Less reactive but still found in Earth's crust.

Transition Metals: Used in construction and jewelry. Good conductors.

Lanthanides: Rare earth metals, used in electronics and magnets.

Actinides: Mostly radioactive and used in nuclear energy.

Halogens (Group 17): Reactive nonmetals, form salts with metals.

Noble Gases (Group 18): Stable gases, do not react easily.

Helium has a full outer shell (2 electrons), making it stable and unreactive, just like other noble gases.

Ionization Energy: Increases across a period, decreases down a group.

Atomic Radii: Decreases across a period, increases down a group.

Electron Affinity: Becomes more negative across a period.

Electronegativity: Increases across a period, decreases down a group.