Understanding Metal Properties and Lightness

When we talk about a metal being "lightest," we are typically referring to its density. Density is a fundamental physical property of a substance that measures its mass per unit volume. A material with lower density is considered "lighter" than a material with higher density, assuming equal volumes are compared. The formula for density (\(\rho\)) is given by:

\[\rho = \frac{m}{V}\]

where \(m\) is the mass and \(V\) is the volume.

To determine which among the given metals is the lightest, we need to compare their densities. The options provided are Aluminium, Tin, Lead, and Copper. Let's look at the approximate densities of these metals:

Comparing Densities to Find the Lightest Metal

Based on the density values listed in the table:

• Aluminium has a density of approximately 2.7 \(\text{g/cm}^3\).
• Tin has a density of approximately 7.3 \(\text{g/cm}^3\).
• Lead has a density of approximately 11.3 \(\text{g/cm}^3\).
• Copper has a density of approximately 9.0 \(\text{g/cm}^3\).

Comparing these values, we can see that Aluminium has the lowest density (2.7 \(\text{g/cm}^3\)) among the four metals. A lower density means that for the same volume, Aluminium would have less mass compared to Tin, Lead, or Copper.

Therefore, Aluminium is considered the lightest metal among the given options. Its low density makes it useful in applications where weight is a critical factor, such as in aerospace and automotive industries.

Conclusion on Lightest Metal

By comparing the densities of Aluminium, Tin, Lead, and Copper, it is clear that Aluminium has the lowest density. This indicates that Aluminium is the lightest metal among the choices provided.

Let's re-examine the options:

• Aluminium (Density \(\approx\) 2.7 \(\text{g/cm}^3\))
• Tin (Density \(\approx\) 7.3 \(\text{g/cm}^3\))
• Lead (Density \(\approx\) 11.3 \(\text{g/cm}^3\))
• Copper (Density \(\approx\) 9.0 \(\text{g/cm}^3\))

The smallest value among these densities is 2.7 \(\text{g/cm}^3\), which corresponds to Aluminium.

Revision Table: Metal Properties Summary

Additional Information on Metal Density

While density is often used to describe how "light" or "heavy" a metal is, it's important to remember that it is an intensive property, meaning it doesn't depend on the amount of the substance. Atomic weight, on the other hand, is the average mass of atoms of an element. Although there is often a correlation between atomic weight and density (heavier atoms packed tightly tend to result in higher density), it's not a direct proportional relationship due to differences in crystal structure and atomic packing efficiency. For instance, Gold (Au) has a much higher atomic weight than Lead (Pb), and also a higher density (\(\approx\) 19.3 \(\text{g/cm}^3\)). However, comparing Lead and Copper, Lead has a higher atomic weight but also a higher density, illustrating the general trend. But the most accurate way to compare the "lightness" of equal volumes of different metals is by comparing their densities.