Atomic Number
9
Element 9
Fluorine (F)
Fluorine is a chemical element with symbol F and atomic number 9. It is the lightest halogen and exists as a highly toxic pale yellow diatomic gas at standard conditions.
Atomic Mass
18.998 u
Category
Halogen
Period
2
Group
Group 17: halogens
Phase
gas
Density
0.001696 g/cm3
Electron Shells
2, 7
Atomic Structure
Protons: 9. Electrons: 9. Neutrons: Varies by isotope.
Electron configuration: 1s² 2s² 2p⁵
Why Fluorine Matters
Fluorine helps connect atomic number 9, halogen behavior, period 2 trends, and electron shell structure. Its gas phase, atomic mass of 18.998 u, and electron configuration 1s² 2s² 2p⁵ make it useful for comparing bonding patterns across the periodic table.
Discovery and Occurrence
Fluorine was discovered 1886 by Henri Moissan. Fluorine is a chemical element with symbol F and atomic number 9. It is the lightest halogen and exists as a highly toxic pale yellow diatomic gas at standard conditions.
Safety and Handling Context
Fluorine belongs to the halogen family, where many pure elements are reactive and irritating or toxic at high concentrations. Classroom work should use approved compounds and teacher guidance.
Related Elements
Frequently Asked Questions
- What is the atomic number of Fluorine?
- Fluorine has atomic number 9, which means a neutral atom has 9 protons and 9 electrons.
- What is the chemical symbol for Fluorine?
- The chemical symbol for Fluorine is F.
- What category is Fluorine in?
- Fluorine is classified as a halogen and sits in period 2 of the periodic table.
Explore Fluorine in 3D
Use the interactive table above to rotate atomic models, compare periodic trends, and move from Fluorine to neighboring elements without losing your place.