Chapter 2 - Bonding Flashcards
(19 cards)
What is a covalent bond
A strong electrostatic attraction between two nuclei and a shared pair of electrons
What is a sigma bond
An end on overlap of two orbitals (p or S) causing the formation of a single covalent bond
What is a pi bond
A sideways overlap of two P orbitals that forms a double or triple bond and cannot form until a sigma bond has formed
Where is the electron density in a pi bond
Electron density is above and below the molecule
How does a triple bond form
One sigma bond and two pi bonds
How do you increase the strength of a covalent bond
Increasing the number of bonds and decreasing the bond length
Define electronegativity
The ability for an atom to attract to a bonding pair of electrons in a covalent bond
How is a dative covalent bond formed
It is formed when an empty orbital of one atom overlaps with an orbital containing a lone pair of electrons of another atom
How is a dot and cross diagram displayed
With an arrow
What is the shape of a molecule determined by
The repulsion between pairs of electrons both lone and bonding
The electrons arrange themselves around the central atom so that their repulsion is minimal
Lone pair-lone pair repulsion> lone pair -bond pair repulsion > bond pair - bond pair repulsion
Linear
2 bond pairs
0 lone pairs
Bond angle: 180*
Linear
2 bond pairs
0 lone pairs
Bond angle: 180*
Trigonal planar
3 bond pairs
0 lone pairs
120* bond angle
Tetrahedral
4 bonds
0 lone pairs
109.5* bond angle
Trigonal pyramidal
1 lone pair
3 bonds
107* bond angle
Trigonal bipyramidal
5 bonds
0 lone pairs of electrons
90* and 180* bond angles
Bent/ V-shaped
2 lone pairs
2 bonds
104.5* bond angle
Octahedral
6 bonds
0 lone pairs of electrons
90* bond angle
Why can H2O form a hydrogen bond but CO2 cannot
Oxygen is more electronegative than H and C
Results in a polar bond with oxygen delta - and C and H delta +
CO2 is a linear molecule (no lone pairs) so dipole moments cancel
Lone pairs of oxygen in water mean that the dipole moments do not cancel
