Unit 2: Chemical Bonding, Intermolecular Forces, and Water Chemistry

Vocabulary practice flashcards covering chemical bonding models, electronegativity, molecular geometry, intermolecular forces, and the chemical properties of water.

Chemical Bond

The forces holding atoms together in a compound that result from the interactions of valence electrons due to the attraction forces ($F_A$) and repulsion forces ($F_R$) between two atoms.

Bond Length (Stabilization Distance)

The distance between the nuclei of two atoms where the attractive forces equal the repulsive forces ($F_A = F_R$), stabilizing the bond.

Formula Unit

The smallest repeating unit of an ionic compound, which is composed of a metal and a non-metal.

Ionic Bonding

The strong electrostatic force of attraction between large numbers of oppositely charged positive and negative ions arranged in a three-dimensional crystal lattice.

Electrovalency

The electrical charge on an ion, written as a small positive or negative superscript to the top right of an element's chemical symbol (e.g., $\text{Na}^+$, $\text{Cl}^-$).

Covalent Bond

A chemical bond formed by the sharing of a pair of electrons between two or more non-metal atoms so that both achieve the electron configuration of the closest noble gas.

Molecule

A particle composed of atoms joined together by covalent bonds.

Diatomic Molecule

A molecule that consists of only two atoms, such as $H_2$, $O_2$, or $Cl_2$.

Electronegativity (EN)

The tendency of an atom to attract shared electrons towards itself when forming chemical bonds, calculated without units from ionization energy (I.E.) and electron affinity (I.A.).

Non-Polar Covalent Bond

A bond where bonding electrons are shared equally or nearly equally between atoms, characterized by an electronegativity difference of $\Delta\text{EN} \le 0.4$.

Polar Covalent Bond

A bond where bonding electrons are shared unequally and pulled closer to the more electronegative atom, creating partial charges ($\delta^+$ and $\delta^-$) with an electronegativity difference between $0.4$ and $1.7$ (or $0.5 \le \Delta\text{EN} \le 1.7$).

Dipole

A molecule possessing two electrically charged poles on opposite ends due to an asymmetrical distribution of polar bonds and vectors.

VSEPR Theory

Valence Shell Electron Pair Repulsion Theory; a model stating that valence electron pairs surrounding a central atom orient themselves as far apart as possible in 3D space to minimize electron-electron repulsion.

Intramolecular Bonds

Forces that hold atoms together within a molecule, including ionic, polar covalent, and non-polar covalent bonds.

Intermolecular Forces (IMF)

Attractive forces between separate molecules that are weaker than intramolecular bonds and determine physical properties such as melting point, boiling point, and hardness.

Van der Waals Forces

The collective name given to intermolecular forces, encompassing London dispersion forces, dipole-dipole interactions, and hydrogen bonding.

London Dispersion Forces (LDF)

The weakest intermolecular force, existing between all molecules and noble gas atoms, caused by momentary instantaneous dipoles that induce dipoles in neighboring particles.

Dipole-Dipole Interaction

An intermolecular attraction between the permanent dipoles of two separate polar covalent molecules, where the slightly positive end ($\delta^+$) of one molecule attracts the slightly negative end ($\delta^-$) of another.

Hydrogen Bonding

A strong, specialized type of dipole-dipole interaction occurring when hydrogen is covalently bonded to an extremely electronegative atom: fluorine ($\text{F}$), oxygen ($\text{O}$), or nitrogen ($\text{N}$).

Cohesion

The tendency of water molecules to cling to other water molecules via hydrogen bonding, which is responsible for surface tension.

Adhesion

The attraction of water molecules to other substances with which they can form hydrogen bonds.

Capillary Action

The spontaneous movement of a liquid through a narrow space, cylinder, or porous material against gravity, driven by the combined effects of cohesion and adhesion.

High Specific Heat

The amount of heat that must be absorbed or expended to change the temperature of $1\,\text{g}$ of a substance by $1\,^\circ\text{C}$.

High Heat of Vaporization

The amount of energy required to convert $1\,\text{g}$ of liquid water into a gas, which is $586\text{ calories}$.

Hydrophilic

A term describing substances that are attracted to water and dissolve readily in it because water is a polar solvent that forms hydrogen bonds.

Hydrophobic

A term describing non-polar substances that are repelled by water and do not dissolve in it, in accordance with the 'like dissolves like' principle.

pH Scale

A logarithmic scale ranging from $0$ to $14$ expressing the hydrogen ion ($\text{H}^+$) concentration in a solution, mathematically defined as $\text{pH} = -\log[\text{H}^+]$.

Carrie Sammut Unit 2 Bonding Test

The assessment scheduled for Thursday, October 29, covering ionic bonding, covalent bonding, electronegativity, VSEPR theory, and intermolecular forces, scored out of a total of $55$ marks ($20$ multiple-choice marks and $35$ short-answer marks).