Metals and Non-Metals

All elements in the periodic table are broadly classified into metals, non-metals, and metalloids based on their physical and chemical properties. Metals and non-metals show contrasting behavior in terms of structure, bonding, and reactivity. Metals generally have 1–3 electrons in their valence shell and tend to lose electrons to form positive ions (cations). Non-metals have 4–7 valence electrons and tend to gain or share electrons to form negative ions (anions) or covalent bonds.

A. Metals

Metals are elements that are typically hard, strong, lustrous, and good conductors of heat and electricity. They are mostly found in nature in the form of ores in the Earth’s crust.

Physical Properties

1. Good conductors of heat and electricity
2. Malleable (can be beaten into thin sheets)
3. Ductile (can be drawn into wires)
4. Lustrous (shiny appearance)
5. Sonorous (produce a ringing sound when struck)
6. Generally solid at room temperature (exception: mercury)
7. High density and high melting points (in most cases)

Chemical Properties

1. Metals react with oxygen to form metal oxides, which are generally basic in nature (some like aluminum oxide are amphoteric).
2. Many metals react with water to form metal hydroxides and hydrogen gas; the reactivity depends on their position in the reactivity series.
3. Metals react with dilute acids (like HCl, H₂SO₄) to form salt and hydrogen gas.
4. Metals tend to lose electrons easily and form positive ions (cations), hence they act as reducing agents.
5. Highly reactive metals can react vigorously with air and moisture, leading to corrosion or rapid oxidation.
6. Some metals react with bases (e.g., zinc, aluminum) to form complex salts and hydrogen gas.

Uses

• Construction (iron, steel)
• Electrical wiring (copper, aluminium)
• Machinery, vehicles, and tools
• Cooking utensils (good heat conductors)
• Medical and biological roles (iron in blood, calcium in bones)

B. Non-Metals

Non-metals are elements that lack metallic properties and are generally soft, dull, and poor conductors of heat and electricity. They exist in all three states of matter.

Physical Properties

1. Poor conductors of heat and electricity (exception: graphite)
2. Not malleable or ductile; brittle in solid state
3. Non-lustrous (dull appearance)
4. Not sonorous
5. Exist as solids, liquids, or gases at room temperature
6. Usually have lower density and melting points

Chemical Properties

1. Non-metals react with oxygen to form non-metal oxides, which are generally acidic or neutral in nature.
2. Non-metals usually do not react with water, but some may react indirectly or under specific conditions.
3. They generally do not react with dilute acids to produce hydrogen gas.
4. Non-metals tend to gain or share electrons, forming negative ions (anions) or covalent compounds, hence they act as oxidizing agents.
5. Non-metals react with metals to form ionic compounds and with other non-metals to form covalent compounds.
6. Some non-metals (like chlorine) are highly reactive and participate in displacement or combination reactions.

Uses

• Oxygen for respiration and medical purposes
• Nitrogen and phosphorus in fertilizers
• Chlorine for water purification and disinfectants
• Sulphur and phosphorus in matches and fireworks
• Iodine as an antiseptic

Difference Between Metals and Non-Metals