Chemistry · Periodic Classification Of Properties · NEET
In a metal, the atoms sit in fixed positions (a lattice) surrounded by a 'sea' of free-moving electrons. When you hammer or pull the metal, the layers of atoms slide over each other, but the free electrons still hold everything together, so the metal changes shape without breaking. Non-metals do not have this electron sea; their atoms are held by fixed covalent bonds, so they crack instead of bending. That is why gold can be beaten into very thin sheets and copper can be drawn into long wires.
Both mean a metal can change shape without breaking, but the shape is different. Malleability = can be beaten or rolled into thin SHEETS (think 'mallet' = hammer). Ductility = can be pulled or stretched into thin WIRES (think 'duct' = a long tube). Gold and silver are the most malleable; gold and copper are very ductile. NEET tip: same reason behind both (sliding layers + free electrons), only the direction of force differs.
Metals have loosely held outer (valence) electrons that leave their atoms and move freely through the whole piece of metal. When you apply a voltage, these free electrons drift and carry the electric current. For heat, the fast-moving free electrons pass on energy quickly from the hot side to the cold side. Non-metals lack free electrons, so they are poor conductors (insulators). This free-electron idea is the single reason behind conductivity, malleability and ductility.
Metals are on the LEFT side and CENTRE of the periodic table (s-block, d-block, f-block and the lower-left of the p-block). Non-metals are on the top-right. A zig-zag line separates them, and elements touching that line (like Si, Ge, As) are metalloids. NCERT states metals make up more than 78% of all known elements, so most of the table is metallic. Metallic character increases down a group and decreases left-to-right across a period.
The free electrons in a metal reflect light that falls on the surface, giving the shiny metallic lustre. Strong attraction between the positive metal ions (kernels) and the electron sea is called metallic bonding; it is strong, so most metals are solids with high melting points and are hard and dense. Exceptions exist for NEET: mercury (Hg) is liquid, and caesium and gallium melt at very low temperatures.
They go together. 'Metallic character' means how easily an element loses electrons and behaves like a metal. The more metallic an element, the more it shows metal properties: malleability, ductility, shininess and good conductivity. So an element high in metallic character (like Na, K) is more clearly metallic than one low in it (like P, Si). NEET often tests the ORDER of metallic character rather than the property list directly.
The correct order of increasing metallic character of Na, Be, P, Mg and Si is:
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Gold is both the most malleable and one of the most ductile metals. It can be hammered into extremely thin sheets (gold leaf) and pulled into very long, thin wires without breaking, thanks to its soft, easily sliding metal lattice.
Almost all metals conduct electricity well because of their free electrons. Silver, copper and gold are the best conductors. A few metals conduct less well, but even the poorest metal conducts far better than any non-metal.
Graphite is an exception. It is a non-metal (a form of carbon), but each carbon uses only 3 of its 4 valence electrons for bonding, leaving one free electron per atom to move between layers. This gives graphite metal-like conductivity, which is why NEET treats it as a special case.
Most metals have high melting points because metallic bonding (attraction between positive ions and the electron sea) is strong. Exceptions important for NEET are mercury (liquid at room temperature), and caesium and gallium, which melt at very low temperatures.
Higher metallic character means the element more strongly shows metal properties, including malleability and ductility. Since metallic character increases down a group and decreases across a period, elements at the lower-left of the table are the most malleable and ductile.
