Chemistry: Chemical Bonding, Solids, Alloys, and Molecular Properties

Vocabulary flashcards covering principles of spectrophotometry, alloy structures and properties, lattice energy, types of solids, electronegativity metrics, and enthalpy of fusion.

Absorbance and Transmittance Relationship

An inverse relationship where as absorbance increases, transmittance decreases.

Molar Absorptivity and Path Length in Beer's Law

Parameters used in spectrophotometry calculations, noted with a molar absorptivity constant of $5.00 \times 10^3\,\text{cm}^{-1}\,\text{M}^{-1}$, a path length of $1.00\,\text{cm}$, and an absorbance of $0.6300$.

Interstitial Alloy

A metal alloy formed when smaller atoms are added into the spaces between the host metal atoms in the lattice.

Substitutional Alloy

A metal alloy formed when solute atoms replace host metal atoms in the crystal lattice.

Rigidity and Hardness in Alloys

Properties that make alloys harder and less malleable than pure metals because different-sized atoms disrupt the lattice structure, making atomic layer sliding harder.

Alloy Density ($D = \frac{m}{V}$)

The ratio of mass to volume in an alloy; if mass increases while volume stays the same, density increases ($D \uparrow$), whereas if volume increases while mass stays the same, density decreases ($D \downarrow$).

Lattice Energy ($\text{LE}$)

The energy of an ionic lattice that increases ($\text{LE} \uparrow$) as ionic charge increases, and decreases ($\text{LE} \downarrow$) as ion size and the number of electron shells increase (increasing distance between nuclei).

Melting Point and Lattice Energy Relationship

The correlation where higher ionic charges and smaller ionic radii produce a higher lattice energy ($\text{LE}$), resulting in a higher melting point ($\text{MP}$).

Ionic Solids

Solids composed of metal and nonmetal ions ($(+)$ and $(-)$) characterized by high melting points, general brittleness and hardness, nonconductivity as solids, and electrical conductivity when melted or dissolved in water.

Molecular Solids

Solids composed of nonmetal molecules held by weak forces, exhibiting low melting points, low enthalpy of fusion, softness, variable solubility depending on polarity, and lack of electrical conductivity.

Network Covalent Solids

Solids composed of covalently bonded nonmetal atoms that have very high melting points, high hardness, very strong structures, and insolubility, and do not conduct electricity.

Metallic Solids

Solids formed by metal atoms that have variable melting points and enthalpies of fusion, are insoluble in water, malleable, ductile, and conduct electricity both as solids and when melted.

Periodic Trend of Electronegativity ($\text{EN}$)

The trend where electronegativity values on the periodic table increase from left to right across a period and upward within a group.

$\text{C}-\text{H}$ Bond Polarity Exception

A carbon-hydrogen bond that is classified as nonpolar by exception despite being composed of different nonmetal elements.

Average Electronegativity ($\text{Avg EN}$)

Calculated by $\frac{\text{EN}_1 + \text{EN}_2}{2}$, measuring how strongly the bonded atoms collectively attract electrons.

Difference in Electronegativity ($\Delta\text{EN}$)

Calculated by $|\text{EN}_1 - \text{EN}_2|$, measuring the disparity in electron attraction; a larger $\Delta\text{EN}$ indicates more polar bonding and greater ionic character.

Electronegativity Classification of Bonds

Bond character categorized by electronegativity metrics: Ionic bonds have medium $\text{Avg EN}$ and high $\Delta\text{EN}$; Metallic bonds have low $\text{Avg EN}$ and low $\Delta\text{EN}$; Covalent bonds have high $\text{Avg EN}$ and low $\Delta\text{EN}$.

Enthalpy of Fusion ($\Delta H_{\text{fus}}$)

The energy required to melt $1\,\text{mol}$ of a substance; a high $\Delta H_{\text{fus}}$ indicates more energy is required to melt the solid, while a low $\Delta H_{\text{fus}}$ indicates less energy is required.