bonding

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Questions and Answers

why are metals good conductors of electricity

-the delocalised sea of electrons (valence electrons) are mobile, so can move freely throughout the metallic lattice -these mobile electrons can carry a charge throughout the structure, and the mobile sea of e- move toward the positive terminal of power supply while the positive metal ions remain stationary in their fixed positions

why are metals good conductors of heat

-e- within sea of e- are mobile and so can carry heat energy (as kinetic energy) throughout metal lattice -the vibration of metallic ions also contributes to the flow of heat through the metal lattice

why are metals malleable and ductile

bonding btwn metal ions and sea of e- is non-directional -individual metal cations can move in relation to each other without breaking the bonds between them and the sea of electrons -allowing metal to change shape

why are metals solid at room temperature

-strong attractive forces between metal ions and sea of e- hold the metallic lattice together -as a result lots of thermal energy is needed to disrupt the lattice and allow the metal to melt hence the high melting point hence solid at room temperature Signup and view all the answers

why are ionic solids poor conductors of electricity in the solid phase

in ionic solid the IONS are tightly held in fixed positions within lattice -thus unable to move and carry charge <ul> <li>e- within ionic lattice are also tightly held by individual ions and hence also unable to move and carry charge through the ionic solid -absence of mobile charged particles means ionic solids are non-conductors of electricity</li> </ul> Signup and view all the answers

why are ionic compounds good conductors of electricity when molten/(aq)

-individual cations and anions are mobile and can carry charge throughout the ionic liquid (or solution) -(aq): their mobility and charge enable them to conduct an electric current through the sol'n -both +ve and -ve ions carry charge, and the cations move toward -ve electrode while anions move toward +ve electrode -hence conducting electricity Signup and view all the answers

why are ionic compounds hard and brittle

-if large force applied to ionic lattice, cause layers of ions to move -causing charged ions to align alongside one another -so like charges will align, repulsive forces will exceed attractive forces, and hence the layers will repel, causing the lattice to break apart rather than dent or bend Signup and view all the answers

why do ionic compounds have high melting and boiling points

-strong electrostatic attractive forces between ions -strong attractive forces extend throughout ionic lattice keeping individual ions in fixed postions -thus large thermal energy needed to overcome these strong electrostatic forces of attraction hence the high melting and boiling point Signup and view all the answers

why are covalent molecular substances non-conductors of electricity in either solid, liquid or aqueous phase

-e- within covalent molecular substance are localised within each atom's electron cloud or as shared electrons within covalent bonds, hence it being immobile -these substances don;'t contain ions, -the absence of any freely mobile charged particles explains why covalent molecular substances are non-conductors of electricity Signup and view all the answers

why are covalent molecular substances soft and weak

-covalent molecular substances exhibit weak intermolecular forces between neighbouring molecules -hence require low amount of thermal energy to overcome these weak attractions -hence they're weak and soft Signup and view all the answers

why are covalent network substances non-conductors of heat or electricity

e- in these substances are held in fixed positions within the atom's shells, lone pairs or covalent bonds hence it's immobile absence of charged mobile particles = unable to conduct electricity or heat through substance Signup and view all the answers

Study Notes

Conductivity of Metals

Metals possess free-moving delocalized electrons, allowing efficient conduction of electricity.
High concentration of these electrons results in strong electrical conductivity in metals.
Metals conduct heat well due to free electrons transferring energy rapidly through the lattice structure.

Properties of Metals

Malleability allows metals to be hammered or pressed into shapes without breaking; ductility permits stretching into wires.
Metallic bonding provides flexibility, allowing layers of atoms to slide over each other without breaking bonds.
Most metals are solid at room temperature due to strong metallic bonds that require high energy to overcome.

Behavior of Ionic Solids

Ionic solids are poor conductors of electricity in the solid phase because charged ions are fixed in a lattice and cannot move freely.
When molten or dissolved in water, ionic compounds conduct electricity well as ions can move freely in a liquid state.

Strength and Hardness of Ionic Compounds

Ionic compounds are hard and brittle due to strong electrostatic forces between tightly packed oppositely charged ions, which break upon stress.
High melting and boiling points arise from these strong ionic bonds, requiring significant energy to break apart the lattice structure.

Characteristics of Covalent Molecular Substances

Covalent molecular substances are non-conductors of electricity across all phases because they lack charged particles that can move freely.
Typically soft and weak, these substances have low intermolecular forces (e.g., van der Waals forces), leading to easy deformation.

Properties of Covalent Network Substances

Covalent network substances are structured with a large number of covalent bonds, making them poor conductors of heat and electricity.
The rigid structure results in high melting and boiling points, but the absence of free-moving electrons or ions leads to non-conductivity.