States of Matter and Chemical Bonding Flashcards

Vocabulary flashcards covering gaseous, liquid, and solid states of matter, allotropes of carbon, types of chemical bonding, molecular geometry via VSEPR theory, electronegativity, and intermolecular forces.

Ideal Gas

A theoretical gas composed of molecules in constant random motion in straight lines, behaving as rigid spheres with no intermolecular forces and zero molecular volume.

Elastic Collision

A collision between gas molecules or between gas molecules and the container walls in which no kinetic energy is lost.

Ideal Gas Equation

The equation $pV = nRT$, where $p$ is pressure in $Pa$, $V$ is volume in $m^3$, $n$ is the number of moles, $R$ is $8.31\text{ J}\text{ K}^{-1}\text{mol}^{-1}$, and $T$ is temperature in $K$.

Evaporation

A surface phenomenon where liquid particles with sufficient energy escape as gas, occurring at various temperatures below the boiling point.

Boiling

A phase change occurring throughout the entire body of a liquid at a specific temperature, where internal gas bubbles form as attractive forces are disrupted.

Giant Ionic Lattice Structure

A three-dimensional structure of oppositely charged ions held together by strong electrostatic forces in a repeating array, as in $NaCl$.

Brittleness of Ionic Solids

The tendency of ionic crystals to shatter under stress because applied force shifts layers so that ions of the same charge align side by side, causing strong electrostatic repulsion.

Simple Molecular Structure

A structure composed of isolated molecules held internally by strong covalent bonds and held together externally by weak intermolecular van der Waals forces, as seen in solid iodine $I_2$.

Buckminsterfullerene ($C_{60}$)

A carbon allotrope molecule containing 60 carbon atoms arranged in pentagons and hexagons forming a sphere, held together in bulk by weak van der Waals forces.

Carbon Nanotubes

Cylindrical carbon structures made of graphite-like sheets that exhibit high melting point, extreme strength, maximum reactivity, and higher electrical conductivity than bulk graphite due to delocalized electrons.

Diamond

A giant molecular allotrope of carbon in which each carbon atom forms 4 single covalent bonds in a 3D tetrahedral network, resulting in extreme hardness, high melting point, and electrical insulation.

Graphite

A giant molecular allotrope of carbon where each carbon atom forms 3 single covalent bonds in 2D sheets, leaving 1 delocalized electron per atom to conduct electricity while weak van der Waals forces between layers allow them to slide.

Silicon(IV) Dioxide ($SiO_2$)

A giant molecular crystalline substance with a structure similar to diamond, where each silicon atom is bridged to its neighboring silicon atoms by an oxygen atom.

Metallic Bonding

The strong electrostatic attraction between positively charged metal cations and a surrounding sea or cloud of delocalized electrons.

Malleability

The capability of a metal to be beaten into thin sheets, enabled by the ability of metal cation layers to roll over each other into new positions without breaking the metallic bond.

Ductility

The physical property of metals that allows them to be pulled out into thin wires without disrupting the metallic bonding structure.

Ionic Bond Strength Factors

Properties determining ionic bond strength: higher ionic charge creates stronger bonds ($Mg^{2+} > Na^+$), and smaller ion size allows closer proximity and stronger attraction.

Co-ordinate (Dative Covalent) Bond

A specialized covalent bond where both shared bonding electrons are provided by the same single atom, such as the lone pair sharing in $NH_3 + H^+ \rightarrow NH_4^+$.

VSEPR Theory

Valence Shell Electron Pair Repulsion theory, which states that electron pairs around a central atom repel each other and position themselves as far apart as possible to minimize repulsion.

Electron Pair Repulsion Order

The relative strength of repulsion between electron pairs: lone pair-lone pair > lone pair-bond pair > bond pair-bond pair.

Linear Geometry

A molecular shape with 2 bonding electron pairs arranged at a bond angle of $180^{\text{o}}$, as seen in $BeCl_2$.

Trigonal Planar Geometry

A molecular shape with 3 bonding electron pairs arranged at a bond angle of $120^{\text{o}}$, as seen in $BF_3$.

Tetrahedral Geometry

A molecular shape with 4 bonding electron pairs arranged at a bond angle of $109.5^{\text{o}}$, as seen in $CH_4$.

Trigonal Pyramidal Geometry

A molecular shape containing 3 bonding pairs and 1 lone pair of electrons, resulting in a bond angle of $107^{\text{o}}$, as seen in $NH_3$.

Non-linear (V-shape) Geometry

A molecular shape containing 2 bonding pairs and 2 lone pairs of electrons, where greater lone pair repulsion compresses the bond angle to $104.5^{\text{o}}$, as seen in $H_2O$.

Electronegativity

A chemical property measuring an atom's ability or tendency to attract a bonding pair of electrons in a covalent bond.

Polar Bond

A covalent bond featuring an unequal distribution of shared electrons, creating a separation of charge with a partial positive end ($\text{δ}^+$) and a partial negative end ($\text{δ}^-$).

Permanent Dipole Forces

Intermolecular attraction occurring between polar molecules that maintain permanent charge separation ($\text{δ}^+ - \text{δ}^-$) due to electronegativity differences.

Temporary Dipoles (van der Waals Forces)

Weak intermolecular forces caused by the continuous, random motion of electrons creating short-lived temporary charge imbalances in non-polar molecules.

Hydrogen Bond

An intermolecular force formed when a hydrogen atom covalently bonded to a highly electronegative atom ($F$, $O$, or $N$) is attracted to an unshared electron pair on another electronegative atom.