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11 Na Sodium 22.989769282

Sodium

ALKALI METAL
Bohr Model: Electrons arranged in energy shells around the nucleus.

Sodium /ˈsoʊdiəm/ is a chemical element with symbol Na (from Ancient Greek Νάτριο) and atomic number 11. It is a soft, silver-white, highly reactive metal. In the Periodic table it is in column 1 (alkali metals), and shares with the other six elements in that column that it has a single electron in its outer shell, which it readily donates, creating a positively charged atom - a cation.

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Quick Facts

Atomic Number 11
Period 3
Group 1
Phase Solid
Appearance silvery white metallic
About Alkali Metals

Alkali metals are highly reactive, soft, silver, and shiny metals found in Group 1. They readily lose their outermost electron to form positive ions (cations) with a charge of +1.

History

Discovered By Humphry Davy
Named By Unknown

Physical Properties

Atomic Mass 22.989769282
Density 0.968 g/L
Molar Heat 28.23 J/(mol·K)
Phase Transition (Melting & Boiling Points)

Sodium melts at 370.944 K and boils at 1156.09 K.

Atomic Properties

Electron Config [Ne] 3s1
Electronegativity 0.93
Electron Affinity 52.867 kJ/mol
Ionization Energy 495.8 kJ/mol
Orbital Filling Diagram
This diagram visualizes electron configuration according to the Aufbau principle and Hund's rule. Boxes represent orbitals (s, p, d, f), while arrows indicate electrons with spin up or down. Electrons fill lower energy levels first and occupy orbitals singly before pairing.
Emission Spectrum Emission spectrum of Sodium

Photograph

Image of Sodium Source: Wikipedia

External Resources

Wikipedia PubChem Royal Society of Chemistry Periodic Videos (YouTube)

Study Guide

Atomic Number

The number of protons in the nucleus, which defines the element.

Atomic Mass

The average mass of an atom, including protons and neutrons.

Electronegativity

A measure of how strongly an atom attracts electrons in a bond.

Ionization Energy

The energy required to remove an electron from an atom.

Electron Config

The arrangement of electrons in the atom's energy shells.