The World of Metals and Non-metals - Substances that Behave Differently from Metals and Non-metals
Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Metalloids (Semimetals): These are elements that exhibit properties of both metals and non-metals. They are located along the 'stair-step' line in the periodic table.
Physical Properties of Metalloids: They are typically solids at room temperature, have a metallic luster (look like metals), but are brittle and shatter like non-metals when struck.
Electrical Conductivity: Metalloids are semi-conductors, meaning they conduct electricity better than non-metals but not as well as metals. Their conductivity can be improved by adding small amounts of other elements.
Noble Gases (Inert Gases): These are elements that are extremely unreactive because they have a stable, full outer electronic shell. They exist as monoatomic gases (single atoms).
Uses of Metalloids: Elements like Silicon () and Germanium () are crucial in the electronics industry for making transistors and microchips.
Uses of Noble Gases: Helium () is used in balloons due to its low density; Argon () is used in light bulbs to prevent the filament from burning; Neon () is used in advertising signs.
📐Formulae
💡Examples
Problem 1:
Why is Silicon () classified as a metalloid rather than a metal or a non-metal?
Solution:
Silicon () is classified as a metalloid because it possesses a metallic luster (looks like a metal) but is brittle (a property of non-metals) and acts as a semi-conductor.
Explanation:
Metalloids share characteristics of both groups. Silicon's ability to conduct electricity is between that of a conductor like Copper () and an insulator like Sulfur ().
Problem 2:
A substance 'X' is a gas at room temperature, does not react with any other element, and is used to fill weather balloons. Identify 'X'.
Solution:
The substance 'X' is Helium ().
Explanation:
Helium is a Noble Gas. Its chemical inertness (unreactivity) and low density make it ideal for use in balloons. Since it belongs to Group 18, it does not form compounds easily.
Problem 3:
Compare the conductivity of a metal and a metalloid as temperature increases.
Solution:
For a metal, conductivity decreases as temperature increases. For a metalloid like Germanium (), conductivity increases as temperature increases.
Explanation:
This unique property of metalloids makes them essential for electronic components that operate at different temperatures.