"AP Chemistry - Unit 4 Review"

Chemical Bond

Attractive force that holds groups of atoms together to make them function as a unit.

To become more stable and reach their lowest energy state.

Why do atoms form?

Ionic compound

A compound that results when a metal reacts with a nonmetal to form a cation and an anion.

Ionic bonding

The electrostatic atttraction between oppositely charged particles.

Cations

Atoms that lose electrons and become positively charged

Anions

Atoms that gain electrons and become negatively charged

Formula Unit

The simplest ratio of an Ionic compound's ions.

Lattice Energy

The energy required to completely separate a mole of solid ionic compound into its gaseous ions. It implies the overall bond formation, the strength of ionic bonds, and why it is exothermic.

The charge and radius of the ions (always +)

Lattice Energy depends on what?

To complete an octet.

Why do IONIC bonds form?

Electronegativity

The tendency of atoms in a molecule to attract electrons to itself.

Charge on ions.

What has the biggest influence on Lattice Energy?

Shorter and stronger

Multiple bonds are what?

Molecule

Neutral group of atoms held together by covalent bonds.

Molecular compound

Chemical compound whose simplest units are molecules.

Exceptions to Octet Rule

Odd number of electrons.

Less than an octet.

Expanded Octet (central atom with principal quantum number n > 2.)

Violations of the Octet Rule

Be, B, P, S, and Xe

Formal Charge

Difference between the valence electrons on a free molecule and the valence electron assigned to an atom.

VSPER Thoery

Valence Shell Electron Pair Repulsion. Lone pairs repel more than shared pairs do.

Sigma bonds

Bonds from overlapping orbitals. Single bonds.

Pi bonds

Bonds between adjacent p orbitals. Double and triple bonds.

Hybridization

A redistribution of the energy of orbitals of individual atoms to give orbitals of equivalent energy for the bonded atoms.

Linear bond angle

180

Triganol planar bond angle

120

Tetrahedral bond

109.5

2 Domains

Linear

3 Domains

Triganol planar

4 Domains

Tetrahedral

5 domains

Triganol bipyramidal

6 domains

Octahedral

2 bonds, 1 lone pair

Bent

3 bonds, 1 lone pair

Trigonal pyramidal

2 bonds, 2 lone pairs

Bent

4 bonds, 1 lone pair

Sawhorse

3 bonds, 2 lone pairs

T-shaped

5 bonds, 1 lone pair

Square pyramidal

4 bonds, 2 lone pairs

Square planar

Increases

As the electronegativity of an element increases, the attraction for a shared pair of electron _____.

Electron Affinity

The energy after an electron is gained by a gaseous ion.

The greater the charge and distance, the greater the what?

Dipole moment

Bond energy

Strength of bonding interaction that measures the energy required to break a bond.

Bond length

Distance bewteen the nuclei of the two atoms connected by a bond.

Bonding pair

Pairs of electrons found in the space between the bonded atoms.

Couloumb's Law

Equation used to calculate the energy of interaction between a pair of ions.

Covalent bonding

Type of bonding in which electrons are shared by atoms.

Polar

Description of a molecule having a dipole moment.

Dipole moment

Property of charge distribution that can be represented by partial positive and negative.

Double bond

Bond in which two pairs of electrons is shared by two atoms. 1 sigma and 1 pi.

Duet rule

Forms stable compounds with two electrons.

Isoelectric ions

Ions containing the same number of electrons as a noble gas

Lewis structure

Shows that a molecule is composed of atoms that are bound together by sharing of electrons.

Localized electron model

Shows how the valence electrons are arranged among the atoms in the molecule

Molecular structure

Three-dimensional arrangement of atoms in a molecule

Octet rule

Forms stable compounds with eight electrons.

Polar covalent bonding

Electrons are not shared equally because one atom attracts them more strongly than the other

Resonance

When one or more than one valid Lewis structure can be written for a particular molecule.

Resonance structure

Average electron structures that show resonance within a molecule.

Single bond

Bond in which one pair of electrons is shared by two atoms. 1 sigma

Triple bond

Bond in which three pairs of electrons are shared between two atoms. 1 sigma and 2 pi.

VSPER model

Useful tool in predicting the geometries of molecules formed from nonmetals.

Delocalized electrons

Electrons that are not associated with a single atom or bond or a molecular orbital that extends over several adjacent atoms.