General Chemistry II Flashcards

Flashcards on Kinetic Molecular Theory and Intermolecular Forces

Kinetic Molecular Theory

Matter is composed of tiny particles which are always in motion.

Kinetic Energy

Energy in motion.

Factors that influence the state of matter

Depends on the kinetic energy (which is a function of temperature) and intermolecular forces that exist between molecules.

Intermolecular forces

Exist between molecules whereas intramolecular forces exist between the atoms of a molecule

Postulate #1 of Kinetic Molecular Theory

Matter is made of particles that are constantly in motion.

Postulate #2 of Kinetic Molecular Theory

The amount of kinetic energy in a substance is related to its temperature.

Postulate #3 of Kinetic Molecular Theory

There is space between particles, the amount of space between particles is related to the substance’s state of matter.

Postulate #4 of Kinetic Molecular Theory

Phase changes happen when the temperature of the substance changes sufficiently.

Postulate #5 of Kinetic Molecular Theory

There are attractive forces in between particles called intermolecular forces. The strength of these forces increases as particles get closer together.

London Dispersion Forces

Temporary dipoles, occurs between Nonpolar molecules, Low strength of attraction

Dipole-Dipole Forces

Permanent dipoles, occurs between Polar molecules, Medium strength of attraction

Hydrogen Bonds

Permanent Polar dipoles between H & F, O, N molecules, Medium-High strength of attraction

Ion-Dipole

Full ion and dipole Polar molecules, High strength of attraction

Polarity

It is a state or a condition having both positive and negative charges, especially in case of magnetic or an electrical pole.

Electric dipole

Refers to “two poles”, meaning there is a positive and negative pole within a molecule. Polar attraction happens when two opposite charges are near each other. The negative end of one molecule is attracted to positive end of the other.

Physical Properties

Physical properties of substances are affected by the attractive forces between particles. Greater attraction between molecules means more energy is required to overcome these attractive forces.

INTRAMOLECULAR Forces

To form molecules which are stable, there should be sharing or transfer of electrons which is called intramolecular bonding.

INTERMOLECULAR Forces

Exists between molecules that influences the phase/state of matter. Responsible for the non-ideal behavior of gases and has more influence on condensed states of matter – liquids and solids

Intermolecular force

The force that exists between and among molecules, atoms and ions.

London dispersion force (LDF)

The weakest among all, but present in all condensed phases of matter regardless of the nature of atoms or molecules.

Dipole – Dipole Interactions

Molecules with net dipole moment repel and attract.

Hydrogen Bonding or H-Bond

A special type of dipole-dipole interaction. This occurs when the hydrogen in a molecule is bonded to a highly electronegative atom– fluorine, oxygen or nitrogen (F,O,N).

Ion-Dipole Forces

Acts between an ion (either cation or anion) and a polar molecule.

Melting point

Temperature at which solid turns into liquid.

Boiling point

Temperature at which a liquid turns into gas.

Solubility

The ability of a solid, liquid, or gaseous chemical substance (referred to as the solute) to dissolve in solvent (usually a liquid) and form a solution.

London Dispersion Force Strength and Molecular Mass

The strength of London dispersion forces is stronger with increasing molecular mass as well as its melting and boiling point.

Density

The molecules of a liquid are packed relatively close together. Consequently, liquids are much denser than gases. The density of a liquid is typically about the same as the density of the solid state of the substance.

Viscosity

A measure of a fluid's resistance to flow.

Vapor Pressure

The pressure exerted by the gas in equilibrium with a solid or liquid in a closed container at a given temperature.