Boron

METALLOID

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

Boron is a metalloid chemical element with symbol B and atomic number 5. Produced entirely by cosmic ray spallation and supernovae and not by stellar nucleosynthesis, it is a low-abundance element in both the Solar system and the Earth's crust. Boron is concentrated on Earth by the water-solubility of its more common naturally occurring compounds, the borate minerals.

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Quick Facts

Atomic Number 5

Period 2

Group 13

Phase Solid

Appearance black-brown

About Metalloids

Metalloids have properties intermediate between metals and nonmetals. They often act as semi-conductors, making them essential for electronics.

History

Discovered By Joseph Louis Gay-Lussac

Named By Unknown

Physical Properties

Atomic Mass 10.81

Density 2.08 g/L

Molar Heat 11.087 J/(mol·K)

Phase Transition (Melting & Boiling Points)

Boron melts at 2349 K and boils at 4200 K.

Atomic Properties

Electron Config [He] 2s2 2p1

Electronegativity 2.04

Electron Affinity 26.989 kJ/mol

Ionization Energy 800.6 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.

Photograph

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.