CHEM unit 4 solutions (copy)

Intramolecular Forces

Intramolecular Forces

Exist between atoms with a molecule (ionic bonds, covalent bonds)

Intermolecular Force

Attraction forces between separate molecules

Types of Intramolecular Forces

Ionic bonds and covalent bonds

Types of Intermolecular Forces

London forces, Dipole Dipole, Hydrogen bonds

Ionic Bonds

Complete separation of charges, Electronegativity difference of 1.7 and above

Dipole Dipole Forces

exist between polar covalent molecules, partial separation of charge

Polar molecules

Has one or more dipole, at least one plane of asymmetry

Dipole Moment

The measure of the separation of one end of a bond and/or molecule wit a partial positive charge, and the other end with a partial negative charge.

Attractive force between two polar molecules (Dipole-Dipole force)

Negative dipole of one molecule is attracted to the positive dipole of the other molecule

Hydrogen Bonds

A strong type of dipole dipole force, it exist between hydrogen in one molecule and fluorine, nitrogen, or oxygen in another

London Force

Temporary Dipole-Dipole force, occurs cause electrons always moving, more electrons the stronger the Force, occurs in EVERY substance

Ionic Compounds

Includes the separation of charges, has a crystal lattice, both intra and inter molecular, london forces are also present

Polar covalent compounds

partial separation of charge, Dipole-Dipole attraction, London forces also present

Non-polar covalent compounds

Only London Forces, strength of London Forces depends on how many electrons there are

When heat is added to a substance

Heat increase = molecules moving and vibrating, once they get fast enough they break the intermolecular bonds

During phase changes

all energy is used to break intermolecular bonds, no temperature increase until change finishes

Intermolecular bonds during phase change

They are broken during phase change

Melting points of ionic compounds

Very high because Bonds are strong, bonds are both intra and inter molecular bonds

Melting point in covalent compounds

Covalent bonds do not break under heat changes since intramolecular

Solution

A homogeneous mixture, one substance dissolved in another

Aqueous solution

water is the solvent in this mixture

Solute

Substance in the smaller quantity

Solvent

The substance in the larger quantity

Universal solvent

Water is this type of solvent, when present even in smaller quantity it is still the solvent

Concentration

The amount of solute dissolved in a certain volume of solution

Molarity

When concentration is measured in “moles per liter”

Dilute

reducing the concentration of a solution by adding more solvent

Chemical Change

New substances are formed, INTRAmolecular bonds are broken and formed

Phase Change

Substances changes, but Molecules/Atoms stay the same, INTERmolecular bonds are broken or formed

Entropy

A measure of disorder/chaos, a tendency towards even distribution

Solubility

Depends on intermolecular forces

Breaking the intermolecular bonds of a solute

Solvent dissolving a solute

Non-polar solutes

Dissolved by non polar solvent, not dissolved by polar solvents (do not recognize dipole dipole force of polar solvent, small molecules)

Ionic solids

Dissolves in polar solvents, each ion is pulled away from each other

Dissociation

Separating the ions of an ionic solid

Ionization

Breaking up of a neutral molecule into ions

Organic polar covalent solvents

Molecules are separated from each other but stay intact (dissolved but not ionized)