Covalent molecules Flashcards
What is the bond angle, name, and 3d shape of a covalent molecule that has 2 bonding pairs?
Linear
180°
What is the bond angle, name, and 3d shape of a covalent molecule that has 3 bonding pairs?
Trigonal planar
120°
What is the bond angle, name, and 3d shape of a covalent molecule that has 4 bonding pairs?
Tetrahedral
109.5°
What is the bond angle, name, and 3d shape of a covalent molecule that has 6 bonding pairs?
Octahedral
90°
How do you determine the shape of a molecule with lone pairs?
Lone pairs have a greater repulsive effect than bonding pairs
Lone pair of electrons is held closer to the nucleus of the central atom
Lone pairs repel each other more than bonding pairs repel each other
lone pair of electrons will cause more repulsion in a molecule
Lone pair decreases a bond angle by about 2.5°
What is the bond angle, name and 3d shape of a covalent molecule that has 4 bonding pairs and 0 lone pairs?
Tetrahedral
109.5°
What is the bond angle, name and shape of a covalent molecule that has 3 bonding pairs and 1 lone pairs?
Pyramidal
107°
What is the bond angle, name and shape of a covalent molecule that has 2 bonding pairs and 2 lone pairs?
Non-linear
104.5°
Explain why NH3 has a pyramidal shape & bond angle of 107°
Electron pairs repel to get as far apart as possible
This molecule has 3 bonding pairs of electrons & 1 lone electron pairs
Lone electron pairs repel more than bonding pairs
Therefore the shape is pyramidal and the angle is 107°
How can the shape of a molecule be determined using dative covalent bonding?
Molecules that have a lone pair of electrons can often act as a base
Base is a proton acceptor
Accept the H⁺ ion to form a dative covalent bond
How do you draw the shapes of negative molecular ions?
Use the periodic table to decide how many outer shell electrons the central atom has
Draw the dot & cross diagram
Add 1 extra electron to the central to account for the negative charge on the ion
Decide how many lone pairs are present and how many bonding pairs
