Properties of Metals and Non-metals

Exam Tip: If a question asks about the difference between a metal and a non-metal regarding hammering, remember that metals are malleable (they flatten), while non-metals like coal or sulfur are brittle (they break into pieces).

Sonority and Conduction

When you drop a metal coin on the floor, it produces a distinct ringing sound. This property is called sonority. Metals are "sonorous," meaning they ring when struck, which is why school bells and musical instruments like the sitar or guitar use metal components.

Furthermore, metals are excellent at transferring energy:

1. Heat Conduction: Metals are good conductors of heat. This is why cooking vessels are made of metal, allowing heat to move quickly from the flame to the food.
2. Electrical Conduction: Metals are good conductors of electricity. This allows them to carry electrical current through wires.

The Nature of Non-metals

Non-metals behave very differently from metals. Generally, they are non-lustrous (dull), brittle, and poor conductors of both heat and electricity.

While metals are often used for structural strength, non-metals are essential for life and industry in other ways. For example:

• Oxygen: A non-metal essential for respiration.
• Carbon: The fundamental building block of all life forms.
• Nitrogen: Vital for plant growth and used in fertilizers.
• Chlorine: Used in water purification.

It is important to note that materials like wood, plastic, or glass are not classified as metals or non-metals; those terms are reserved for elements, which are basic building blocks of matter that cannot be broken down into simpler substances.

Alloys: The Best of Both Worlds

Sometimes, scientists combine metals with other elements to create something even better. These mixtures are called alloys.

A famous example is steel, which is a mixture of the metal iron and the non-metal carbon. By combining them, we create a material that is much stronger than pure iron, making it ideal for heavy-duty applications like the cables used in suspension bridges.

Chemical Behavior: Air and Water

The way these materials react with their environment can lead to significant changes.

Corrosion and Rusting

When iron is exposed to both air and water (moist air), it undergoes a chemical change that forms a brown deposit known as rust. This process is called rusting. Other metals also undergo a similar process called corrosion, such as copper developing a green coating or silver turning black.

Oxides: Acidic vs. Basic

When metals and non-metals react with oxygen, they produce different types of oxides:

• Metal Oxides: Generally, when a metal like magnesium burns in air, it forms an oxide that is basic in nature. This means it will turn red litmus paper blue.
• Non-metal Oxides: When a non-metal like sulfur burns, it forms an oxide that is acidic in nature. For example, sulfur dioxide dissolved in water forms sulfurous acid, which turns blue litmus paper red.

Summary Table