15 P Phosphorus 30.974 u

Phosphorus

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Period
3
Group
15
Block
p-block
Phase (STP)
Solid

Phosphorus is essential for life, found in DNA, RNA, and ATP. It exists in several allotropic forms including white and red phosphorus.

Appearance: Waxy white (white phosphorus)

About Phosphorus

Discovered by the alchemist Hennig Brand in 1669, phosphorus was among the first elements isolated in the modern era. It is a reactive nonmetal of atomic number 15 and atomic mass 30.974, appearing most familiarly as a waxy white solid that melts at 317 K. Five valence electrons ([Ne] 3s2 3p3) give an electronegativity of 2.19 and a first ionization energy of 1012 kJ/mol. The element exists in several allotropic forms, including white and red phosphorus. Phosphorus is essential to life, forming part of DNA, RNA, and the energy carrier ATP. It sits in group 15, period 3, below nitrogen.

Physical Properties

Atomic Mass 30.974 u
Density 1.82 g/cm³
Melting Point 44.2 °C
Boiling Point 280.6 °C
Phase at STP Solid
Atomic Radius 98.0 pm

Electronic Properties

Electronegativity 2.19
Ionization Energy 1011.8 eV
Electron Affinity 72.0 eV
Valence Electrons 5

Electron Configuration

Configuration [Ne] 3s² 3p³

Electron Shell Configuration

Phosphorus electron shell configuration P 2e⁻ 8e⁻ 5e⁻
Electron shell structure of Phosphorus — electrons per shell.
Shell Electrons
1 (K) 2
2 (L) 8
3 (M) 5

Position in Periodic Table

Phosphorus position in the periodic table P

Discovery

Discovered by: Hennig Brand
Year: 1669

Block & Period

Block

s p d f

Period

1 2 3 4 5 6 7

Periodic Table

Lanthanides Actinides

Reactions Involving P

Formation of Phosphorus Pentoxide

P₄ + 5O₂ → P₄O₁₀

Synthesis

Phosphate Buffer System

H₂PO₄⁻ ⇌ HPO₄²⁻ + H⁺

Acid-Base

Phosphoric Acid and Sodium Hydroxide (First Neutralization)

H₃PO₄ + NaOH → NaH₂PO₄ + H₂O

Acid-Base

Phosphoric Acid Complete Neutralization

H₃PO₄ + 3NaOH → Na₃PO₄ + 3H₂O

Acid-Base

Phosphoric Acid Second Neutralization

H₃PO₄ + 2NaOH → Na₂HPO₄ + 2H₂O

Acid-Base
View all 6 reactions →

Compounds Containing Phosphorus

Adenosine Triphosphate

C₁₀H₁₆N₅O₁₃P₃

Calcium Phosphate

Ca₃(PO₄)₂

Coenzyme A

C₂₁H₃₆N₇O₁₆P₃S

Diammonium Phosphate

(NH₄)₂HPO₄

Flavin Adenine Dinucleotide

C₂₇H₃₃N₉O₁₅P₂

Glyphosate

C₃H₈NO₅P

Lithium Iron Phosphate

LiFePO₄

Monosodium Phosphate

NaH₂PO₄

Nicotinamide Adenine Dinucleotide

C₂₁H₂₇N₇O₁₄P₂

Phosphine

PH₃

Phosphoric Acid

H₃PO₄

Phosphorus Pentoxide

P₄O₁₀

More Nonmetal

1 H Hydrogen 6 C Carbon 7 N Nitrogen 8 O Oxygen 16 S Sulfur 34 Se Selenium

Frequently Asked Questions

What is Phosphorus?
Phosphorus (P) is a chemical element with atomic number 15. It is a solid at standard temperature and pressure, classified as a nonmetal.
What are the key properties of Phosphorus?
Phosphorus has an atomic mass of 30.974 u, density of 1.82 g/cm³, melting point of 44.2°C, boiling point of 280.6°C.
What is the electron configuration of Phosphorus?
The electron configuration of Phosphorus is [Ne] 3s2 3p3. It is in the p-block of the periodic table.
Who discovered Phosphorus?
Phosphorus was discovered by Hennig Brand in 1669.
What is the electronegativity of Phosphorus?
Phosphorus has an electronegativity of 2.19 on the Pauling scale.