Chem - Lecture 5: Bonding

What is an Ionic Bond?

Metal and non-metal atom.

What is a Covalent Bond?

2 non-metal atoms.

What is Metallic Bonding?

Metal cations imbedded in a sea of mobile valence electrons.

What are the 3 types of interactions within a molecule?

1) Electrons and nuclei attract one another.

2) Electrons repel each other.

3) Nuclei repel each other.

What is bond length?

The separated distance where the molecule has the max energetic advantage over separated atoms.

What is bond energy?

Energy required to break the bond (kJ mol^-1)

When does unequal sharing of electrons occur and what does this result in?

When two different atoms with unequal attractive forces bond. This results in polar covalent bonds.

What is electronegativity vs electron affinity?

Electronegativity: The ability of an atom in a molecule to attract bonding electrons to itself.

Electron Affinity: The energy change when a neutral atom attrac ts an electron to become a negative ion. (X + e^- → X^-)

What is the general trend of electronegativity?

Decreases going down but increases going left to right.

Most ionic solids have a high melting point. Why?

They are held together in a 3D arrangement by the attractive forces of oppositely charged ions.

What are the properties of ionic compounds?

1) Brittle

2) High melting and boiling points

3) Dissolution in water

4) Conductivity

What are the strength of the forces of covalent compounds?

Strong forces within but weak forces between.

What are the properties of covalent compounds?

1) Low melting and boiling points

2) Soft

3) No conductivity

4) Network solids

What are the properties of metals?

1) White and lustrous

2) Conduct heat and electricity

3) Malleable and ductile

What is the electron geometry with 2 & 3 regions?

Linear & Trigonal planar

What is the electron geometry with 4 & 5 regions?

Tetrahedral & Trigonal bipyramidal

What is the electron geometry with 6 regions?

Octahedral

What is the molecular geometry with 2 & 3 regions of BONDING pairs?

Bent & Trigonal pyramidal

What are dipole moments and what does it depend on?

A covalent bond with asymmetrical distribution of electron density. Depends on bond polarities.

What is a sp³, sp², and sp hybrid orbitals?

sp³: One 2s and three 2p orbitals

sp²: One 2s and two 2p orbitals

sp: One 2s and one 2p orbitals

If the electron group geometry is linear, what is the hybridisation, # of hybrid orbitals, & # of p orbitals?

Hybridisation: sp

# of hybrid orbitals: 2

# of unused p orbitals: 2

If the electron group geometry is trigonal planar, what is the hybridisation, # of hybrid orbitals, & # of p orbitals?

Hybridisation: sp²

# of hybrid orbitals: 3

# of unused p orbitals: 1

If the electron group geometry is tetrahedral, what is the hybridisation, # of hybrid orbitals, & # of p orbitals?

Hybridisation: sp³

# of hybrid orbitals: 4

# of unused p orbitals: 0