Bonding & Structure Flashcards
What’s a dative covalent bond?
One of the bonded atoms donates both electrons (a lone pair) being shared
What’s the bond angle of a linear molecule?
180 degrees
What covalent molecule has a shape with bond angles of 120 degrees?
Trigonal Planar
How many bonding pairs and what is the bonding angle of a tetrahedral molecule?
4 bonding pairs
109.5 degrees
How many bonding pairs and the angle does an octahedral molecule have?
6 bonding pairs
90 degrees
Describe the structure and bonding of a pyramidal molecule?
3 bonding pairs and one lone pair causing a bond angle of 107 degrees
By how many degrees does a lone pair decrease a bond angle?
2.5
Describe induced dipole dipole interactions
Occur between the molecules of simple covalent substances with similar electronegativity
The bigger the molecule the larger the surface area and stronger the force
Describe permanent dipole dipole interactions
Between covalent molecules of different electronegativity. One atom with a higher electronegativity has a stronger attraction for the shared pair of electrons
Definition of electronegativity
The power of attraction between a bonded atom and a pair of electrons in a covalent bond
When is a molecule polar?
When it has permanent dipoles and the molecule is unsymmetrical
When is a molecule non-polar?
When the permanent dipoles cancel out because the molecule is symmetrical
Definition of a hydrogen bond
The electrostatic force of attraction between a hydrogen atom and either a nitrogen, oxygen or fluorine atom along the direction of a lone pair
Which is the strongest type of intermolecular force?
Hydrogen bonding
What bonds hold molecules together in simple covalent molecules?
Intermolecular forces
Why do simple covalent molecules have low melting/boiling points?
Contain intermolecular forces between molecules which are relatively weak so require little energy to break
What type of molecule is graphite and describe its structure?
It’s a giant covalent substance. Each carbon atom is covalently bonded to 3 other carbons in a hexagonal arrangement in layers which can slide over each other. Each carbon has one delocalised electron which carries charge so graphite can conduct electricity
Describe the structure and bonding in a diamond?
Each carbon atom is covalently bonded to 4 other carbons in a tetrahedral arrangement
No mobile charge carriers so doesn’t conduct electricity.
What is graphene?
A single atomic layer of graphite
What is an ionic bond?
The electrostatic force of attraction between opposite charged ions
Can ionic substances conduct electricity?
Not when solid as there are no mobile charge carriers. Can when in solution or molten as ions are free to carry charge
Are ionic substances soluble?
Tend to be soluble in water as ions dissociate and interact with polar water molecules
What’s a metallic bond?
The electrostatic attraction between positively charged metal ions and delocalised electrons
Can giant metallic structures conduct electricity?
Yes as delocalised electrons act as mobile charge carriers
