Chemical Bonding

Intramolecular bonding

Bonding within a molecule

Intermolecular bonding

Bonding between molecules

Ionic bonding

The force of attraction between oppositely charged ions in a compound

Ion

A charged atom or groups of atoms

Octet rule

When bonding occurs, atoms tend to reach an electron arrangement with 8 electrons in the outermost energy level

Transition metal

One that had a partially filled d sub-level

Covalent bonding

The sharing of electrons between two or more elements

Valency

The number of bond an atom of an element forms when it reacts with a monovalent atom.

Sigma bond

Formed by the head on overlap of 2 orbitals

Pi bond

Formed by the sideways overlap of p orbitals

Compound

A substance that is made up of two or more different elements combined together chemically.

Atomic (covalent) radius

Half the distance between the nuclei of two atoms of the same element joined by a single covalent bond

Electronegativity

The relative attraction that an atom in a molecule has for the shared pair of electrons in a covalent bond.

Van der waals forces

The weakest of the attractive forces between molecules due to temporary dipoles(non-polar covalent). They are the only forces of attraction for non-polar covalent molecules.

Dipole-dipole forces

Forces of attraction between the negative pole of one polar molecule and the positive pole of another polar molecule

Hydrogen bonding

Hydrogen bond are dipole-dipole attractions between molecules in which hydrogen atoms are bonded to either Nitrogen, Oxygen or Fluorine.

Bond energy

Average energy required to break or form a bond

Molecule

A group of atoms joined together (it’s the smallest particle of an element or compound that can exist independently)

Name the 3 types of intermolecular bonding

1. Non-polar covalent

2. Polar covalent

3. Ionic bonding

Name 3 types of intermolecular bonding

1. Van Der waals

2. Dipole-dipole

3. Hydrogen bonding

What are noble gases

Discovered end of 18th century

Unreactive so we’re called noble gases

React under extreme conditions

Atoms with full outer shells are very stable

Limitations of octet rule

Doesn’t allow for H He or Li which are stable with 2 electrons in pure shell

Transition elements- 18 electron rule

BF3 is stable with only 6 electrons in outer shell

What’s VSEPR

Valence Shell Electron Pair Repulsion theory

Theory states that the shape of a molecule depends on the number of pairs of electrons around the central atom

Name shapes of bonds

1. Linear

2. Trigonal/triangular planar

3. Tetrahedral

4. Pyramidal

5. V-shaped

Linear

180’

2 bond pairs , 0 lone pairs

Eg. BeCl2

Trigonal/triangular planar

120’

3 bond pairs, 0 bond pairs

Eg. BCl3

Tetrahedral

109.5

4 bond pairs , 0 lone pairs

Eg. CH4

Pyramidal

107’

3 bond pairs, 1 lone pairs

Eg. NH3

V-shaped

104.5’

2 bond pairs, 2 lone pairs

Eg. H2O

Explain double and triple bonds

All double and triple bonds are linear in shape

Bond energies for double are stronger than single and triple is the strongest. This is due to sigma bonds being stronger than pi bonds

What’s the difference between single double and triple bonds

Single bonds are sigma bonds

Double bonds are a sigma and a pi bond

Triple bonds are 1 sigma and 2 pi bonds

What are the electronegativity values for covalent and ionic bonds

<0.4 non-polar

0.4-1.7 polar covalent

>1.7 ionic

What is non-polar covalent

Electrons are shared equally within a bond

Temporary dipoles exist

Eg. O2 N2

What is polar covalent

Electrons are shared unequally within a bond

Permanent dipoles exist

The more electronegative atom is the negative dipole

What’s the exception for polar covalent

A molecule might be polar covalent by means of electronegativity but it is actually non-polar because polarity of bonds cancel due to symmetry of molecules.

Always non-polar shapes:

1. Linear(3 atoms only)

2. Trigonal planar

3. Tetrahedral

What is solubility

Intramolecular bonding determines solubility

Like substances dissolve like substances

Water is polar therefore can only dissolve or be polar substances

Oil is non-polar covalent so water and oil don’t dissolve in one another

How to demonstrate whether a liquid is polar or non-polar

Polar covalent substances are attracted to any charge on a rod

Non-polar substances are not attracted to any charge on a rod

Explain boiling points

Boiling points are dependent on intermolecular bonding and molecular mass.

Hydrogen bonding has the highest

Van Der Waals has the lowest

If two molecules have the same bonding the one with the largest molecular mass will have the higher boiling point

How to name ionic bonding stuff

Metals are +

Non metals are -

Positive ion goes first

Multiply each ion by the smallest possible integer to make the total of + and - the same

Place this number as a subscript

Look in copy for more detail