4.9 Comparison of General Physical Properties of Metals and Non-Metals

Thermal Conductivity:

Metals generally have high thermal conductivity, which means they can conduct heat easily. On the other hand, non-metals tend to have poor conductivity, making them less efficient at conducting heat.

Electrical Conductivity:

Metals are good conductors of electricity, because they have free electrons that can move freely in the metal lattice. Non-metals, with few exceptions such as graphite, are poor conductors of electricity because they lack free electrons.

Adaptability:

The metals are malleable and ductile. So, they can be hammered, drawn into wires, or transformed into thin sheets without breaking. This property is due to metallic bonds which allow atoms to shift easily under pressure. Non-metals are neither malleable nor ductile; rather, they are brittle.

Melting Points and Boiling Points:

Metals generally have high melting points and boiling points due to strong metallic bonds that require a lot of energy to break. On the other hand, non-metals often have lower melting points and boiling points because their atoms and molecules are held by weaker bonds such as covalent bonds, van der Waals bonds, or hydrogen bonds that require less energy to break.

Concept Assessment Exercise 4.10

Compare the general properties of metals and non-metals.

Key Points

• When elements are arranged in the order of their increasing atomic number, their properties are repeated in a periodic manner.
• A horizontal row of elements in the periodic table is called a period.
• A column of elements in the periodic table is called a group or a family.
• Group IA and IIA elements are called s-block elements, since s sub-shell fills in these elements.
• Elements in the same group possess similar chemical properties.
• Elements in group IIIA to VIIIA are called p-block elements, because filling of valence p sub-shell occurs in these elements.
• The length of a period in the periodic table depends on the type of sub-shell that fills.
• The decrease in force of attraction between nucleus and the valence electron by the electrons present in the inner sub-shells is called the shielding effect.
• The size of an atom is the average distance between the nucleus of an atom and the outer electronic shell.
• The atomic radii decrease from left to right in a period. Whereas these increase from top to bottom in a group.
• Ionization energy is the minimum amount of energy required to remove the outermost electron from an isolated gaseous atom.
• Electron affinity is the amount of energy released when an electron adds up in the valence shell of an isolated atom to form a uni-negative gaseous ion.

References for Additional Information

• B. Earl and LDR Wilford, Introduction to Advanced Chemistry.
• Jain Brand and Richard Grime, Chemistry (11-14).
• Lawrie Ryan, Chemistry for You.