EL 5 - The molecules of life Flashcards
What is a covalent bond?
A bond formed by electrons being shared between atoms
What is a dative covalent bond?
Involves a triple bond.
One of the pairs of electrons is from the same atom (both bonding electrons).
In a diagram, it is shown with the arrow pointing away from the atom that donates the pair of electrons.
Describe electron pair repulsions
The bonding pairs of electrons arrange themselves so that they are as far apart as possible - this is because similar charges repel (negative and negative)
What is an orbital?
An area of negative charge
Name the seven different shapes of molecules
Tetrahedral, bent, linear, trigonal planar, octahedral, pyramidal, and trigonal bipyramidal
Describe a tetrahedral molecule
4 bonding pairs and 0 non bonding pairs
Bond angle: 109.5 degrees
Describe a bent molecule
2 bonding pairs and 2 non bonding pairs
Bond angle: 104.5 degrees
Describe a trigonal planar molecule
3 bonding pairs and 0 non bonding pairs
Bond angle: 120 degrees
Describe an octahedral molecule
6 bonding pairs and 0 non bonding pairs
Bond angle: 90 degrees
Describe a pyramidal molecule
3 bonding pairs and 1 non bonding pair
Bond angle: 107 degrees
Describe a trigonal bipyramidal molecule
5 bonding pairs and 0 non bonding pairs
Bond angles: 120 and 90 degrees
By how much is the bond angle reduced for each lone pair? (approx.)
Around 2.5 degrees
Give an example of each of the shapes of molecules
Tetrahedral: methane, ammonium ion
Bent: water, sulfur dichloride
Trigonal planar: sulfur trioxide, boron trichloride
Octahedral: sulfur hexafluoride
Pyramidal: methyl ion, ammonia
Trigonal bipyramidal: phosphorus pentachloride
Linear: beryllium chloride, carbon dioxide
Describe a linear molecule
2 bonding pairs and 0 non bonding pairs
Bond angle: 180 degrees
