EL 5 Flashcards
What are ionic bonds?
The electrostatic attraction between oppositely charged ions
How do we draw an ion configuration of a shell that has lots its electrons?
Leave it empty
Describe the structure of a giant ionic lattice
every ion is surrounded by 6 oppositely charged
What are covalent bonds?
The bond formed between atoms with a shared pair of electrons
What type of bond does O2 have?
A double bond
What type of bond does H2 have?
Single
What type of bond does N2 have?
Triple
What is a dative covalent bond?
A shared pair of electrons which have been provided by only one of the bonding atoms
What bonds does an ammonium ion have?
3 single bonds
1 dative covalent
What are the properties of covalent bonds?
- Relatively low melting & boiling point
- They do not conduct electricity (no charged particles)
- Mostly insoluble in water
What is the electron repulsion theory?
Electrons repel as far as possible
What should we include in every answer to an exam Q to do with shapes of molecules?
Electrons repel as far as possible
What type of pairs of electrons don’t influence shape?
Covalently bonded
What type of pairs of electrons influence shape? Why?
Lone pairs because they repel more strongly than bonding pairs
How much will each lone pair reduce the bonding angle by?
2.5 degrees
3 properties of lone pairs
- Can influence a molecule’s shape
- More concentrated regions of negative charge
- repels more than a bonded pair
What is a region of charge?
1 region of charge = single bond OR double bond OR triple bond OR lone pair
How do we figure out the shape of a molecules?
- Draw a dot and cross diagram
- Identify which atom of the molecules is the CENTRAL ATOM
- Count the regions of charge around the central atom
- Work out the bond angles based on the regions of charge
- Identify any lone pairs as this will affect both the shape and the bond angle
- identify the shape
What shape and angle is a molecule with 2 bonding pairs?
Linear - 180 degrees
What shape and angle is a molecule with 3 bonding pairs?
Planar triangular - 120 degrees
What shape and angle is a molecule with 4 bonding pairs?
Tetrahedral - 109.5 degrees
What shape and angle is a molecule with 3 bonding pairs and 1 lone pair?
Pyramidal - 107 degrees
What shape and angle is a molecule with 2 bonding pairs and 2 lone pairs?
Non-linear - 104.5 degrees
What shape and angle is a molecule with 5 bonding pairs?
Bipyramidal - 90 & 120 degrees
What shape and angle is a molecule with 6 bonding pairs?
Octahedral - 90 degrees
How do you draw a covalent bond on plain paper?
Straight line
How do you draw a bond coming towards you on paper?
Triangle pointing towards central atom
How do you draw a bond going away from you on paper?
3 lines increasing in size
