Metals and Non-metals - PHYSIC3.1 PHYSIC3.1 PHYSIC3.1 PHYSIC3.1 PHYSIC AL PROPERTIESAL PROPERTIESAL PROPERTIESAL PROPERTIESAL PROPERTIES

Metals are elements that lose electrons to form positive ions (cations), such as $Na^+$, $Mg^{2+}$, and $Al^{3+}$.

Metallic Lustre: Metals, in their pure state, have a shining surface. Non-metals are generally dull, with the exception of Iodine ($I$), which is a lustrous non-metal.

Hardness: Most metals are hard. However, alkali metals like Lithium ($Li$), Sodium ($Na$), and Potassium ($K$) are soft and can be cut with a knife. Diamond (an allotrope of Carbon) is the hardest natural substance known.

Malleability: Metals can be beaten into thin sheets. Gold ($Au$) and Silver ($Ag$) are the most malleable metals.

Ductility: The ability of metals to be drawn into thin wires. Gold is the most ductile metal; a wire of about $2 \text{ km}$ length can be drawn from $1 \text{ g}$ of gold.

Thermal Conductivity: Metals are good conductors of heat and have high melting points. Silver ($Ag$) and Copper ($Cu$) are the best conductors. Lead ($Pb$) and Mercury ($Hg$) are comparatively poor conductors of heat.

Electrical Conductivity: Metals are good conductors of electricity. Non-metals are poor conductors, except for Graphite (an allotrope of Carbon), which conducts electricity.

State at Room Temperature: All metals except Mercury ($Hg$) exist as solids. Mercury is a liquid at room temperature ($25^\circ\text{C}$). Non-metals exist as solids or gases, except Bromine ($Br$), which is a liquid.

Melting and Boiling Points: Metals generally have high melting points. However, Gallium ($Ga$) and Caesium ($Cs$) have very low melting points and will melt if kept on the palm.

Sonority: Metals produce a ringing sound when struck against a hard object, a property called sonority.