CHEM II Chapter 8, 9, 10

Ionic Compound

Compound where a metal reacts with a nonmetal

Polar Covalent Bond

Unequal sharing of electrons

If Electronegativity = Zero

Bond is covalent

If Electronegativity = Intermediate

Bond is polar covalent

If Electronegativity = Large

Bond is ionic

Dipole Moment

When molecules have a center of positive charge and a center of negative charge

aka when, in a compound, one element has a higher electronegativity than the other

Ion size determines…

Electronegativity increases…

Right way

Electronegativity decreases…

Down way

Cation formation occurs…

On left of periodic table

• electrons occupy high energy orbitals, so can lose electrons high energy electrons but not low —> limits size of positive charge on cations

Anion formation occurs…

On right of periodic table

• electrons occupy low energy orbitals

To create cations…

For main group elements, take electron from highest energy orbital

For transition elements, take uppermost s subshell first before valence d electrons

Cations Size

Smaller than atom formed from

Anions Size

Larger than atom formed from

Bond breaking is a process of

Endothermic process

Bond formation is a process of

Exothermic process

Calculating ΔH for a given reaction

= energy required to break bonds – energy released when bonds form

Calculating Formal Charge

Atom’s group # - [Amount of lone pair electrons + ½ amount of bonding pair electrons]

Electron-Pair Geometry: 2 groups around center

Linear

Bond angle: 180

Electron-Pair Geometry: 3 groups around center

Trigonal-planar

Bond angle: 120

Electron-Pair Geometry: 4 groups around center

Tetrahedral

Bond angle: 109.5

Electron-Pair Geometry: 5 groups around center

Trigonal-bipyramidal

Bond angle: 120 and 90

Electron-Pair Geometry: 6 groups around center

Octahedral

Bond angle: 90

If sum of lone pairs and atoms is 2, the hybridized orbital is…

Two sp orbitals

Unhybridized orbitals: Two p orbitals

If sum of lone pairs and atoms is 3, the hybridized orbital is…

Three sp² orbitals

Unhybridized orbitals: One p orbital

If sum of lone pairs and atoms is 4 the hybridized orbital is…

Four sp³ orbitals

Unhybridized orbitals: None

Geometry of sp hybrid orbital

Linear

Geometry of sp hybrid orbital sp² hybrid orbital

Planar-trigonal

Geometry of sp hybrid orbital sp³ hybrid orbital

Tetrahedral

When 1s orbitals combine…

They form two sigma molecular orbitals

• one bonding, one antibonding

When 2p orbitals combine…

They do

1. Direct head-to-head to form sigma and sigma⁺ molecular orbitals

2. Indirect, parellel to form pi and pi⁺ molecular orbitals

Molecular Geometry of 3 atoms + 0 lone pairs

Trigonal Planar

Molecular Geometry of 2 atoms + 1 lone pairs

Bent

Molecular Geometry of 4 atoms + 0 lone pairs

Tetrahedral

Molecular Geometry of 3 atoms + 1 lone pairs

Trigonal Pyramidal

Molecular Geometry of 2 atoms + 2 lone pairs

Bent

Molecular Geometry of 6 atoms + 0 lone pairs

Octahedral

Molecular Geometry of 5 atoms + 1 lone pairs

Square pyramidal

Molecular Geometry of 4 atoms + 2 lone pairs

Square planar

Molecular Geometry of 5 atoms + 0 lone pairs

Trigonal bipyramidal

Molecular Geometry of 4 atoms + 1 lone pairs

Seesaw

Molecular Geometry of 3 atoms + 2 lone pairs

T-shaped

Molecular Geometry of 2 atoms + 2 lone pairs

Linear

Most likely Resonance is…

The one with the smallest formal charge

Paramagnetism

Presence unpaired electrons

Diamagnetism

Presence of paired electrons

Bond order

(# of bonding electrons - # of antibonding electrons) / 2

Larger bond order

Greater bond strength

Steps for Drawing MO Orbital Energy Diagram

Think of it as combining two atoms of the same element: Atom_A and Atom_B

1. Draw out left to right the amount of electrons in the 1s orbital for the element on both sides

2. Draw the bonding sigma 1s orbital and antibonding sigma 1s orbital

3. Transfer electrons from both sides into bonding sigma 1s orbital first, then antibonding if needed

4. Repeat for sigma 2s, pi 2p, etc

Hydrogen Bonding

When hydrogen reacts with N, O, F