Question

Consult webelements.com to find (a) two metals less dense than water, (b) two metals more dense than mercury, (c) the densest known solid metallic element, and (d) the densest known solid nonmetallic element.

Short answer

(a) Lithium and Potassium; (b) Iridium and Osmium; (c) Osmium; (d) Iodine.

Step-by-step solution

Identify Properties of Water and Mercury

First, we need to identify the densities of water and mercury to compare them with the metals. The density of water is 1 g/cm³, and the density of mercury is approximately 13.6 g/cm³.

Finding Metals Less Dense Than Water

Using an online resource like WebElements, we look for metals with densities less than 1 g/cm³. Lithium (Li) with a density of 0.534 g/cm³ and Potassium (K) with a density of 0.862 g/cm³ are both less dense than water.

Finding Metals More Dense Than Mercury

Next, we find metals with densities greater than 13.6 g/cm³. Iridium (Ir) with a density of 22.56 g/cm³ and Osmium (Os) with a density of 22.59 g/cm³ are metals more dense than mercury.

Identifying the Densest Known Solid Metallic Element

The densest known metallic element can be found by checking the highest density value. Osmium (Os) has the highest density at 22.59 g/cm³, making it the densest metallic element.

Identifying the Densest Known Solid Nonmetallic Element

We review the list of nonmetallic elements and find iodine (I) with a density of 4.93 g/cm³, making it one of the densest nonmetallic solid elements.

Key concepts

Metals Less Dense Than Water

Understanding the density of elements helps us determine how they relate to common substances like water. Water has a density of 1 g/cm³. When we say a metal is "less dense than water," it means its density is lower than this value.

There are very few metals that have densities less than water due to the natural characteristic of metals being quite dense. Two prime examples of such metals are Lithium (Li) and Potassium (K).

• Lithium has a density of 0.534 g/cm³.
• Potassium has a density of 0.862 g/cm³.

These metals are alkali metals, known for their relatively low densities and softness. They are highly reactive, especially with water, so they are typically stored in oil to prevent a reaction in the air.

Metals More Dense Than Mercury

Mercury is a noteworthy benchmark for density comparison with metals, boasting a notable density of around 13.6 g/cm³. When a metal is "more dense than mercury," it signifies that it has an even higher density.

Two metals frequently underlined for their substantial densities surpassing that of mercury are Iridium (Ir) and Osmium (Os).

• Iridium has a density of 22.56 g/cm³.
• Osmium has a density of 22.59 g/cm³.

Both of these metals are transition metals and belong to the platinum group. They are often utilized in applications that require materials to withstand extreme conditions due to their strength and durability.

Densest Metallic Element

The search for the densest metallic element leads us to Osmium (Os). With a remarkable density of 22.59 g/cm³, Osmium is known as the densest naturally occurring metallic element.

Its density is attributable to its extremely compact atomic structure, where atoms are packed closely together. This characteristic gives Osmium not only its density but also its hardness and high melting point.

Due to these properties, Osmium finds use in various industrial applications, including the manufacture of fountain pen nibs, electrical contacts, and pivot bearings.

Densest Nonmetallic Element

While metals often steal the spotlight for their impressive densities, some nonmetallic elements also exhibit considerable density. Iodine (I) stands out as the densest solid nonmetallic element with a density of 4.93 g/cm³.

Iodine's high density among nonmetals is due to its large atomic mass and molecular structure. It is a halogen and is solid under standard conditions, with visible characteristics like a lustrous, metallic sheen.

This element is essential in many fields, including medicine, where it's used for its antiseptic properties, and in contrast media for X-rays and CT scans. Additionally, iodine is vital in nutrition, particularly in the production of thyroid hormones.