DIFFERENCES BETWEEN METALS AN NON METALS

 DIFFERENCES BETWEEN METALS AN NON METALS:

General Physical Properties of Metals:

1. Lustrous (Shiny Appearance): Metals have a characteristic shine or luster due to the free electrons reflecting light.

2. Malleable: They can be hammered or pressed into thin sheets without breaking. This is because the delocalized electrons allow the metal atoms to slide past each other without disrupting the metallic bond. Gold and silver are highly malleable.

3. Ductile: They can be drawn into thin wires. Similar to malleability, this property is due to the mobility of electrons and the ability of metal atoms to rearrange without fracturing the structure. Platinum is highly ductile.

4. Good Conductors of Heat: The free-moving electrons efficiently transfer thermal energy throughout the metal. Silver is the best thermal conductor.

5. Good Conductors of Electricity: The delocalized electrons can easily move throughout the metallic lattice, carrying an electric current. Silver is the best electrical conductor, followed by copper and gold.

6. Solid at Room Temperature (Generally): Most metals are solid at 25∘C.

7. High Melting and Boiling Points: Strong metallic bonds require a significant amount of energy to break, leading to high melting and boiling points.

8. High Density: Most metals are dense due to their closely packed atomic structures.

9. Hard: Generally, metals are hard and strong.

10. Sonorous: They produce a ringing sound when struck, a property known as sonority.

Exceptional Cases and Unusual Properties:

While the above properties are generally true for metals, there are notable exceptions and metals with unique behaviors:

1. State at Room Temperature:

   • Mercury (Hg): This is the most famous exception, as it is a liquid at room temperature (25∘C). Its weak metallic bonding is attributed to relativistic effects.

   • Gallium (Ga), Cesium (Cs), Francium (Fr): These metals have very low melting points and will melt just above or at room temperature. Gallium, for example, melts in the palm of your hand (29.76∘C).

2. Hardness:

   • Alkali Metals (Lithium, Sodium, Potassium, Rubidium, Cesium, Francium): These are very soft metals and can be easily cut with a knife. This is due to their relatively weak metallic bonding, with only one valence electron per atom.

3. Melting and Boiling Points:

   • Sodium (Na) and Potassium (K): As mentioned, these alkali metals have relatively low melting and boiling points compared to most other metals.

   • Tungsten (W): In contrast to the low-melting alkali metals, tungsten has the highest melting point of all metals (3422∘C), making it useful in light bulb filaments.

4. Density:

   • Alkali Metals (e.g., Lithium, Sodium, Potassium): These metals have low densities, with lithium being less dense than water.

   • Osmium (Os) and Iridium (Ir): These are among the densest naturally occurring elements.

5. Conductivity (Electrical and Thermal):

   • Lead (Pb) and Mercury (Hg): While still conductors, they are relatively poor conductors of heat and electricity compared to other metals like copper or silver.

   • Bismuth (Bi): It has unusually low electrical conductivity for a metal and exhibits a high Hall effect.

6. Malleability and Ductility:

• Zinc (Zn), Cadmium (Cd), Mercury (Hg), and Manganese (Mn): These transition elements can be exceptions to typical malleability and ductility, with some being more brittle. For instance, solid mercury is brittle.

• Examples of Metals:

  • Iron (Fe)

  • Copper (Cu)

  • Aluminum (Al)

  • Gold (Au)

  • Silver (Ag)

  • Platinum (Pt)

  • Titanium (Ti)

  • Lead (Pb)

  • Zinc (Zn)

  • Nickel (Ni)

  • Chromium (Cr)

  • Magnesium (Mg)

  • Calcium (Ca)

  • Sodium (Na)

  • Potassium (K)

  • Mercury (Hg) (Unique for being liquid at room temperature)

  
  

General Physical Properties of Non-Metals:

1. Dull Appearance (Non-Lustrous): Most non-metals do not have a shiny or reflective surface; they typically appear dull.

2. Brittle: In solid form, non-metals are generally brittle and will break or shatter easily when hammered or stretched. They are neither malleable nor ductile.

3. Poor Conductors of Heat: Non-metals are generally poor conductors of heat because their electrons are tightly bound and not free to move and transfer thermal energy.

4. Poor Conductors of Electricity: Similar to heat conductivity, non-metals are poor conductors of electricity as they lack free-moving electrons to carry an electric current.

5. Low Melting and Boiling Points (Generally): Many non-metals have relatively low melting and boiling points, and many exist as gases at room temperature. This is because the forces between their individual molecules or atoms are weak.

6. Low Density: Non-metals generally have lower densities compared to metals.

7. Exist in All Three States: At room temperature, non-metals can exist as solids (e.g., carbon, sulfur), liquids (e.g., bromine), or gases (e.g., oxygen, nitrogen, hydrogen).

8. Non-Sonorous: They do not produce a ringing sound when struck.

Exceptional Cases and Unique Properties:

Despite these general trends, non-metals also exhibit some fascinating exceptions:

1. Lustrous Appearance:

   • Iodine (I): This non-metal is a solid at room temperature and has a distinct metallic luster, appearing shiny and greyish-black.

   • Diamond (an allotrope of Carbon): While not typically considered "metallic" in shine, diamond is famously known for its exceptional brilliance and sparkle due to its high refractive index.

   • Graphite (an allotrope of Carbon): Graphite also possesses a somewhat metallic sheen, though it's still duller than typical metals.

2. Electrical Conductivity:

   • Graphite (an allotrope of Carbon): This is the most significant exception. Unlike most non-metals, graphite is an excellent conductor of electricity. This is due to its layered structure where each carbon atom is bonded to three others in a hexagonal array, leaving one free valence electron per atom that can move freely within the layers.

   • Carbon Fibers: Engineered carbon fibers also exhibit good electrical conductivity.

3. Hardness:

   • Diamond (an allotrope of Carbon): Diamond is the hardest known natural substance. This is a remarkable exception, as most solid non-metals are brittle and relatively soft. Its extreme hardness is due to its strong, rigid covalent network structure where each carbon atom is bonded to four other carbon atoms in a tetrahedral arrangement.

4. Melting and Boiling Points:

   • Diamond and Graphite (allotropes of Carbon): These have exceptionally high melting and boiling points due to their strong covalent network structures, requiring a large amount of energy to break their bonds. Diamond, for example, has a melting point well over 3500∘C.

   • Boron (B) and Silicon (Si): These metalloids (elements with properties intermediate between metals and non-metals) also have very high melting points due to their network covalent structures, exhibiting non-metallic characteristics in many ways.

5. State at Room Temperature:

   • Bromine (Br): This is the only non-metal that exists as a liquid at room temperature. Most non-metals are either gases or solids.

6. Density:

   • Diamond: Despite being a non-metal, diamond has a relatively high density compared to most other non-metals.

   • Iodine: Iodine also has a relatively high density for a non-metal.

   • Examples of Non-metals:

     • Oxygen (O)

     • Carbon (C) (e.g., in the form of diamond, graphite, charcoal)

     • Nitrogen (N)

     • Hydrogen (H)

     • Sulfur (S)

     • Chlorine (Cl)

     • Bromine (Br) (Unique for being liquid at room temperature)

     • Iodine (I)

     • Phosphorus (P)

     • Fluorine (F)

     • Neon (Ne) (A noble gas, a type of non-metal)

     • Helium (He) (A noble gas, a type of non-metal)

     • Silicon (Si) (Often considered a metalloid, but shares many non-metallic properties)

     • Boron (B) (Also often considered a metalloid, but largely non-metallic)