Bonding Flashcards
covalent bonding
Has a pair of Electrons with opposed spin shared between two atoms with each atom giving one election
Ionic bonding
Bond formed by the electrical attraction between positive and negative ions ( Cation and anions)
coordinate bonding
Covalent bond in which both shared electrons come from one of the atoms
Attractive and repulsive forces
All bonding results from electrical attractions and repulsions between the protons in the nucleus and the electrons which with attractions are weighing repulsions
Attractive and repulsive forces and covalent bonds
Electrons in the pair between atoms repel one another but this is overcome by their attractions to BOTH nuclei.
If atoms get too close together the nuclei and their inner electrons will repel those of the other atom, so the bond has a certain length
Electrons spin must be opposite for the bonds to fall
Attractive and repulsive forces and ionic bonds
Cations and anions are arranged so that each cation is surrounded by several anions and vice versa to maximise attraction and minimise repulsion
Repulsions from inner electrons and nuclei prevent the ions from getting too close together
Electronegativity
Measure of the electron attracting power of an atom in a covalent bond
polar bond
Has one end of the bond with a slightly positive charge than the other end with a slightly negative charge
Eg. Dipole
Molecule is neutral overall
Intermolecular bonding
The weak bonding holding the molecules together
Eg. In liquids
Governs the physical properties of the substance
intramolecular bonding
Strong bonding between the atoms in the molecule and governs its chemistry
Van der waals forces
Includes all types of intermolecular forces weather dipole or induced dipole
Three types of intermolecular forces
dipole-dipole forces
Induced dipole induced dipole forces
Hydrogen bonds
Dipole to dipole forces
Polar molecules have dipoles- one end is slightly positive and the other sightly negative due to differences in electronegativities between atoms
Attraction between negative and positive regions
Dipole forces- permanent dipole
Induced dipole to induced dipole forces
Forms when the electron orbitals around a molecule are influenced by another charged particle
Hydrogen bonds
Interaction between H atom bonded to small, very electronegative elements which have lone pairs- F,O,N
They are highly electronegative and the H atom is so small, plus charge in bonded hydrogen atom is spread over small volume and it has high charge density
Highly polarising
Effect of hydrogen bonding in boiling and melting temperatures
hydrogen bonds are stronger than van der Waals forces- Molecules that form hydrogen bonds have a higher BP
Effect of hydrogen bonding in solubility
Most significant intermolecular forces between water molecules are hydrogen bonds.
Covalent compounds that can replace these bonds by forming new hydrogen bonds with water will dissolve
Valence shall electron pair repulsion theory (VSEPR)
Any loan pays present around central Atom provide additional repulsive forces, which change the bond angle and shape of molecule
Eg For every lone pair present, bond angle between covet and bond is reduced by 2.5
Shape of molecules and ions
- Find number of Electrons in outer shell
- Add one electron for each bond being formed
- (add 1 electron for 1-, remove one electron for 1+)
- Divide total number of Electrons by two to find number of electron pairs
- Compare number of electron pairs with number of bonds to find number of bonding pairs and lone pairs
Metallic bonding
force of attraction between free moving delocalised electron and a positive metal
Group 4 hydrides, group 5 and 6
The boiling temperatures increase as you go down the group because the molecules are getting larger with more electrons, and so the van der Waals forces become stronger
value for NH3 and H20
Much higher than other hydrides in their groups because extra energy is needed to break the hydrogen bonds between molecules
Linear shape
2 bonding pairs
0 number of lone pairs
Eg. Co2, BeCl2
Bond angle- 180
trigonal planar
3 no. Of bonding pairs
No lone pairs
BF3 AICl3, 120
Tetrahedral
Four bonding pairs
No lone pairs
CH4 NH4+, 109.5
Bent or V shaped
2 bonding pairs
2 lone pairs
Eg. H2O F2O, 104.5
Loan pay - loan pay propulsion forces the bonding pays even closer and reduces angle between them to 104.5
Trigonal pyramidal
3 bonding pairs
1 lone pairs
Eg. NH3 H3O+, 107
There is more potion between a lone pair and a bonding pair than between two bonding pairs and forces bonding pairs together slightly reducing bond angle
Octahedral
6 bonding pairs
0 lone pairs
Eg. SF6, 90
Triagonal bipyramidal
5 bonding pairs
0 Lone pairs
Eg. PCl5, 120, 90
Propulsion between bonding pairs means that three of the atoms are in the plane at 120 and other two atoms are at right angles
electronegativity in periodic table
Increases a longer. As atomic radius decreases
Decreases down a group as shielding increases
Fluorine is the most electronegative
The higher the electronegativity, the better the element can attract bonding electrons
non polar covalent bonds
If electronegatively difference between two atoms is less than 0.4
polar covalent bonds
If difference is between0.4 and 1.9
More ionic bond
If the difference is about 2.0 or more
