Department of Energy Argonne National Laboratory Office of Science NEWTON's Homepage NEWTON's Homepage
NEWTON, Ask A Scientist!
NEWTON Home Page NEWTON Teachers Visit Our Archives Ask A Question How To Ask A Question Question of the Week Our Expert Scientists Volunteer at NEWTON! Frequently Asked Questions Referencing NEWTON About NEWTON About Ask A Scientist Education At Argonne Element Density and Hardness
Name: George
Status: student
Grade: other
Location: TX
Date: November 2007

Is there a direct correlation between density and softness of metals, i.e, lead and gold are dense but soft, where as iron is less dense but harder?

There is no "simple" correlation between the density and the softness of metals I am aware of because the two properties depend upon various properties of the metals. The density of a metallic element is dominated by its atomic number and weight and how the atoms "pack" in the structure of the solid.

The hardness of a metal is also related to the atomic number and weight of the atoms, but is also much more sensitive to the bonding between metal atoms. In general, the more complex the metallic structure, the "harder" the metal will be. The two properties of metals, density an hardness/softness, are not related in a simple way. To take an extreme example: sodium and potassium are relatively light metals, but are very "soft". You can cut them with a dull knife. Tungsten is comparatively dense, but relatively very hard and brittle.

Vince Calder

Click here to return to the Chemistry Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (, or at Argonne's Educational Programs

Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012
Weclome To Newton

Argonne National Laboratory