PARTICLE INTERACTIONS IN CHEMISTRY – UNIT REVIEW

Electronegativity

The ability of an atom to attract bonding electrons to itself, measured on a scale where higher values indicate stronger attraction. It's essential in determining bond type and molecular behavior.

Electronegativity Difference (ΔEN)

The difference in electronegativity between two bonded atoms, used to predict the type of bond. A ΔEN of 1.7 or greater indicates an ionic bond, while values between 0.4 and 1.7 suggest polar covalent bonds, and below 0.4 indicates non-polar covalent bonds.

Ionic Bond

A bond formed between a metal and a non-metal through the transfer of electrons, resulting in the formation of charged ions. Characterized by high melting and boiling points, and typically soluble in water.

Covalent Bond

A bond formed between two non-metals where electrons are shared, leading to the formation of molecules. Covalent bonds can be single, double, or triple, depending on the number of shared electron pairs.

Polar Covalent Bond

A type of covalent bond where electrons are unequally shared between two atoms with different electronegativities, resulting in a dipole moment, where one end of the molecule has a partial negative charge and the other has a partial positive charge.

Non-Polar Covalent Bond

A covalent bond where electrons are shared equally between two identical non-metal atoms, leading to no dipole moment and a balanced charge distribution.

Dipole

A molecule that has both a positive and a negative charge due to uneven electron distribution, typically occurring in polar molecules, which results in varying interactions with other molecules.

Lattice Energy

The energy released when ions in a gas phase form an ionic solid. It is influenced by the charges of the ions and the distance between them, reflecting the strength of the ionic bond.

Hydration Energy

The amount of energy released when ions are surrounded by water molecules, which stabilizes the ions in solution and affects solubility.

Molecular Polarity

The overall polarity of a molecule determined by the arrangement of its polar bonds and the molecular geometry. A molecule is polar if it has a net dipole moment.

Intermolecular Forces

Forces that occur between molecules, affecting their physical properties such as boiling points and solubility. These include hydrogen bonds, dipole-dipole interactions, and London dispersion forces.

London Dispersion Forces

Weak intermolecular forces resulting from temporary shifts in electron density within molecules, which create temporary dipoles that induce attractive forces between nearby molecules.

Dipole-Dipole Forces

Attractive forces between polar molecules due to their permanent dipole moments, leading to a higher boiling point compared to non-polar substances of similar molecular weight.

Hydrogen Bonding

A strong type of dipole-dipole interaction that occurs when hydrogen is bonded to highly electronegative atoms (N, O, or F), significantly influencing the physical properties of compounds such as water.

Ion-Dipole Forces

Attractive forces between an ion and a polar molecule, which play a crucial role in the solubility of ionic compounds in polar solvents.

Atomic Radius

The distance from the nucleus of an atom to the outer boundary of its electrons. It generally increases down a group and decreases across a period due to increased nuclear charge and electron shielding.

Bond Polarity

The distribution of electrical charge over the atoms joined by the bond, influenced by the electronegativities of the atoms involved, affecting molecular behavior and interactions.

Molecular Symmetry

The spatial arrangement of atoms in a molecule that can affect its polarity; symmetrical molecules tend to be non-polar, while asymmetrical molecules are often polar.

Potential Energy

The energy held by an object because of its position relative to other objects, which can convert to kinetic energy during reactions or changes in state.

Kinetic Energy

The energy that an object possesses due to its motion, which can influence rates of reaction and state changes in physical chemistry.

Polar Molecule

A molecule that has a net dipole moment due to its shape and the difference in electronegativity between its atoms, causing it to interact differently with other polar and non-polar substances.

Non-Polar Molecule

A molecule that does not have a net dipole moment and has equally distributed charges, typically not interacting favorably with polar solvents.