Chem H Bonding UNIT

H2O lewis structure

NH3 lewis structure

CH4 lewis structure

H2 lewis structure

H-H

N2 lewis structure

O2 lewis structure

CO2 lewis structure

C2H6 lewis structure

C2H4 lewis structure

C2H2 Lewis Structure

C2H5OH lewis structure

but 4 dots on O

Br₂

linear, nonpolar

C₂H₂

linear, nonpolar

C₂H4

trigonal planar (C-H), nonpolar

CCl₂O

trigonal planar, polar

CH₂O

trigonal planar, polar

CH₄

tetrahedral, nonpolar

CI₄ (1-carbon, 4-iodine)

tetrahedral, nonpolar

Cl₂

linear, nonpolar

CO₂

linear, nonpolar

H₂O

bent, polar

H₂S

bent, polar

HCl

linear, polar

HCN

linear, polar

HF

linear, polar

N₂

linear, nonpolar

NH₃

pyramidal, polar

NI₃

pyramidal, polar

PCl₃

pyramidal, polar

SiF₄

tetrahedral, nonpolar

SO₃

trigonal planar, polar

H₂O

NH₃

CH₄

CF₂Cl₂

SO₃

O₃

SO₂

CH₃OH

*Ionic Bonding

Occurs when electrons are transferred between

atoms. Formed by the attraction between a metal and

nonmetal

Cation

Formed when the metal donates one or more electrons to the nonmetal

Anion

Formed when a nonmetal accepts one or more electrons

*"CO"valent Bonding

Occurs when pairs of electrons are shared between atoms.When atoms have different electronegativities, these

electrons are shared "unfairly".

Types of bonds:

- Single: 2 electrons shared

- Double: 4 electrons shared

- Triple: 6 electrons shared

Octet Rule

Elements prefer to have eight valence electrons in their outer

shells. Hydrogen and Helium are exceptions.

Ionic Bonding

Transfer of electrons from one atom to another

Covalent Bonding

sharing of

electrons between two atoms

Steps for writing Lewis Structures

1. Add up the valence electrons for all atoms in

the compound. (Be careful to add or subtract

electrons for ions)

2. Place the least electronegative element at

the center (except for hydrogen)

3. Add SINGLE covalent bonds to connect the

atoms.

4. Add lone (unshared) pairs to the outer atoms.

5. Add lone pairs to the center atom.

6. Check all atoms for octet rule (having 8

electrons, except for H and He). If necessary,

move electrons to create double or triple bonds.

7. If applicable, draw the charge of the ion. For a

polyatomic ion, put the whole Lewis structure in

brackets first.

A lone pair is any 2 electrons not in a covalent bond

Sulfate ion

• SO42̶

• 6 + (6 x 4) + 2= 32 valence electrons

Ammonium ion

• NH4+

• 5 + (1 x 4) - 1 = 8 valence electrons

Carbon

• C

• 4 valence electrons

bond moment (dipole)

a vector that indicates the size of the polarity of a particular covalent bond (within a molecule)- points in the direction of the more electronegative atom

(in the eg- The C−H and C=C bonds are non-polar bonds, so have no bond moments associated with them)

dipole moment

sum of individual bond moments. If the molecule has an overall dipole moment it is polar- the moment will indicate its direction

EG- The molecule on the left had two bond moments

which, by vector addition, give the overall dipole

moment shown.

polar molecule

molecule that has an overall dipole moment

Intramolecular forces

forces that hold the atoms together in a molecule

Intermolecular forces

interactions between molecules (much weaker)

intermolecular force strength

measures by: boiling and melting point- the higher, the stronger the forces

Types of intermolecular forces:

Dipole-dipole

Ion-dipole

Dipole-induced Dipole

Dipole-dipole forces

forces between polar molecules (partially charged)- opposite poles match up by electrostatic attraction

Ion-dipole forces

forces between a fully charged species (ion) and a dipole by electrostatic attraction.

Increase in strength with increase in charge or decrease in size of ion

(how ions are dissolved in water- attract to the H2O and pulled away by electrostatic charge)

Dipole-induced-dipole forces

forces arising from temporary dipoles induced in atoms by ions with a permanent dipole (either ion or dipole).

Temporary dipoles created when non-polar molecule interacts with polar- temporarily shifts the electrostatic charge to attract the polar molecule, then returns when removed

Hydrogen bonds

A special dipole-dipole interaction between a Hydrogen atom and either N, O, or F atom (smallest and most electronegative on PT)

- the lone pair on either N, O, F (in a molecule) is what causes the bond- strongest interaction with H

- reason why solid form of water floats on liquid form- H bonds- once frozen becomes less dense than liquid

surface tension

Surface tension is the amount of energy required to stretch the surface area of a liquid by unit area

- strong intermolecular force = strong surface tension

viscosity

Measure of fluids resistance to flow

- strong intermolecular force = high viscosity

solubility

- Polar compounds dissolve other polar compounds

- Non-polar compounds dissolve non-polar

- Polar compounds insoluble in non-polar

Intermolecular Force

Force between molecules

Intramolecular Force

Force within a molecule

Covalent Bond

Force of attraction within a molecule created by the sharing of electrons

Ionic Bond

Force of attraction created by the transfer of electrons between atoms

Polar Molecule

A molecule in which the covalent bonds are asymmetrically arranged

Nonpolar Molecule

A molecule in which the covalent bonds are symmetrically arranged

London Dispersion Force

Intermolecular force between nonpolar molecules

Heavier molecule = stronger force

Longer Chain molecule = more polarizable

Dipole-Dipole Force

Intermolecular force between polar molecules

Heavier Molecules = More Polarizable=Stronger Forces

Hydrogen Bond

Intermolecular force between molecules containing hydrogen bonded to N, O, or F

More H-O, H-N, H-F connections= Stronger Force

Boiling point

Temperature at which the vapor pressure is equal to the atmospheric pressure

delocalized electrons

electrons that are free to move

Isomers

Compounds with the same formula (mass)but different structures.

Cation

A positively charged ion

Anion

A negatively charged ion

ion-dipole interactions

occurs between ion (from an ionic compound) and a molecule from a polar covalent substance.

Can a London Force form between HI and HBr?

No, because they form dipole-dipole forces.

Forces between atoms in a compound are ______________ ______.

intramolecular forces

Forces that act between molecules are ______________ ______.

intermolecular forces

_____ _________ have very strong bonds (attractive forces) so they have high melting points and boiling points.

ionic compounds

________ _________ have lower melting and boiling points because covalent bonds are not as strong as ionic bonds.

covalent compounds

Generally, intermolecular forces are much ______ than intramolecular forces.

weaker

We can use _________________ to predict what kind of bond will form.

electronegativity

_____ _________ are like a battery, they have a positive and a negative end (like two poles of a planet or a magnet); the ends are opposite of each other.

polar molecules

A ______-______ _____ happens between the partial charges of polar molecules.

dipole-dipole force

The ____ polar the molecules are, the stronger the dipole-dipole forces between them, and thus, the higher the boiling point.

more

________ _____ involve the attraction between polar molecules that contain hydrogen and molecules that have N-H, O-H, or F-H bonds.

hydrogen bonds

________ _____ are very strong because hydrogen atoms are small and very polar (a large difference in electronegativity between atoms).

hydrogen bonds

Water has unique properties because of all the strong ________ _____.

hydrogen bonds

______ __________ ______ are nonpolar molecules, like F₂, which can become momentarily polar which results in a force of attraction between the molecules.

London dispersion forces

In ______ __________ ______, electrons are moving around in atoms, so there may be times when the electron distribution is not symmetrical).

London dispersion forces

___-______ ______ are the interaction or attraction between an ion and a polar molecule.

ion-dipole forces

An example of ___-______ _____ includes any ionic compound that dissociates into ions when dissolved in water (like NaCl in water or AgNO₃ in water).

ion-dipole forces

In _____, because the particles are so far apart, the attractive forces between them do not have a great effect.

gases

_____ are fluids and can flow easily because the particles move freely.

gases

In ______, particles can only vibrate in place and do not break away from their fixed positions.

solids

In ______, the particles are held very close together by attractive forces.

solids