The key difference between arsenic and phosphorous is that arsenic is a nonmetal whereas phosphorous is a metalloid.

Arsenic and phosphorous are both in the p block of the periodic table of elements. They can be found in nature as minerals where these elements occur in combination with other elements such as oxygen and sulfur. Although we cannot find phosphorous in its pure elemental form, arsenic can be found as a free element.

CONTENTS

1. Overview and Key Difference
2. What is Arsenic
3. What is Phosphorus
4. Side by Side Comparison – Arsenic vs Phosphorus in Tabular Form
5. Summary

What is Arsenic?

Arsenic is a chemical element having atomic number 33 and chemical symbol As. And, this chemical element occurs as a grey coloured metalloid material. Moreover, arsenic naturally occurs in different minerals; e.g. in combination with other elements such as sulfur and metals. However, we can find it as pure elemental crystals as well. Furthermore, there are several different allotropes of arsenic, but the isotope with the metallic appearance is mostly used in industrial applications. Arsenic occurs in nature as a monoisotopic metalloid. That means it has a single stable isotope.

Figure 01: Arsenic

Besides, arsenic is a p-block element. It is located in group 15 and period 4 of the periodic table. The electron configuration of this metalloid is [Ar]3d104s24p3. Furthermore, this metalloid is in a solid-state at room temperature. Upon heating, it can undergo sublimation.

There are three common allotropic forms of arsenic: grey, yellow and black arsenic. The most common and useful form is grey arsenic. The crystal structure of arsenic is rhombohedral. When considering its magnetic properties, arsenic is diamagnetic. Grey arsenic is a brittle material due to the weak chemical bonding between the layers of the allotrope.

What is Phosphorous?

Phosphorous is a chemical element having atomic number 15 and chemical symbol P. There are two main forms of phosphorous as white and red phosphorous. However, due to its highly reactive nature, we cannot find a free elemental form of phosphorous.

Figure 02: Allotropes of Phosphorous

Moreover, black phosphorous is the thermodynamically most stable allotrope of phosphorous at room temperature. It occurs in two forms as alpha form and beta form. The alpha form is the most stable allotrope and it forms when we heat red phosphorous at 803K. Meanwhile, the beta form of phosphorous forms when we heat white phosphorous at 473K.

What is the Difference Between Arsenic and Phosphorus?

Arsenic is a chemical element having atomic number 33 and chemical symbol As. Phosphorous is a chemical element having the atomic number 15 and chemical symbol P. The key difference between arsenic and phosphorous is that arsenic is a nonmetal whereas phosphorous is a metalloid.

Moreover, we can find arsenic as a pure chemical element in crystal form while we cannot find phosphorous in its pure elemental form due to the high reactivity.

Below infographic summarizes the difference between arsenic and phosphorous.

Summary – Arsenic vs Phosphorus

Arsenic and phosphorous are both in the p block of the periodic table of elements. They can be found in nature as minerals where they occur in combination with other elements such as oxygen and sulfur. However, we cannot find phosphorous in its pure elemental form but arsenic can be found as a free element. The key difference between arsenic and phosphorous is that arsenic is a nonmetal whereas phosphorous is a metalloid.

Reference:

1. “Phosphorus.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 11 Oct. 2019, Available here.
2. “Phosphorus.” Wikipedia, Wikimedia Foundation, 25 Mar. 2020, Available here.

Image Courtesy:

1. “Arsenic-24481” By Rob Lavinsky, iRocks.com – (CC BY-SA 3.0) via Commons Wikimedia
2. “PhosphComby” By Weißer_Phosphor.JPG: BXXXD at German WikipediaPhosphor_rot.jpg: Tomihahndorf at German WikipediaPhosphor-rot-violett.jpg: Maksimderivative work: Materialscientist (talk) – This file was derived from:✦ Weißer Phosphor.JPG✦ Phosphor rot.jpg✦ Phosphor-rot-violett.jpg (CC BY-SA 3.0) via Commons Wikimedia

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