1.4 - Bonding Flashcards
Define Ionic Bond
An ionic bonding is the result of electron transfer from metals to non-metals. This results in the formation of positive and negative ions.
The ionic bonds are held together by the electrostatic force of attraction between the oppositely charged ions.
Define Metallic Bond
In metal structures, metal atoms lose their outer electrons.
Metallic bonding is the electrostatic attraction between the sea of delocalised valence electrons and the nuclei of the positively charged metal ions. (Lattice formation)
Define covalent Bond
Covalent bonding is the result of electron sharing between atoms to provide stability.
A covalent bond is the electrostatic force of attraction between between the negatively charged electron pair and the positively charged nuclei of the elements.
What are the forces of attraction and repulsion in a covalent bond?
Attraction - The electron pair to the positively charged nuclei
Repulsion - Between the electron pair and between the nuclei
What is a net balance?
Net balance is the overall attraction or repulsion.
In ionic crystals there is a balance
To form bonds attraction must outweigh repulsion
Define coordinate bond
What is another name for this type of bond?
A covalent bond in which both of the shared electrons come from the same atom.
Dative Bond = Coordinate Bond
Define electronegativity
The measure of an atom’s ability to attract electrons in a covalent bond.
What atom are the electrons attracted toward?
The more electronegative atom
What difference in electronegativity defines a Polar Covalent bond?
Between 0.3 - 1.8
What difference in electronegativity defines a Pure Covalent bond?
Less than 0.3
Define Dipole
A dipole is the slight charge an atom can get in a molecule. It occurs when electrons are drawn towards the more electronegative element, creating charge.
What are the three intermolecular forces?
Dipole-dipole force
Induced dipole - Induced dipole force
Hydrogen bonds
What can Dipole forces collectively be referred to as?
Van der Waal’s Forces
Define Permanent Dipole
A permanent dipole occurs when one atom is more electronegative than the other within a molecule. Electron are drawn to the more electronegative creating a negative charge. The opposite side therefore takes up a positive charge.
Define Dipole - Dipole Forces
Dipole - dipole forces are a force of attraction between oppositely charged dipoles on different molecules.
Dipoles are not always aligned due to the movement of molecules
What factor effects dipole-dipole force?
The difference in electronegativity effects the strength of the attraction. The more electronegative one side is, the greater attraction of electrons. Therefore, stronger charge, therefore stronger force of attraction between oppositely charged dipoles between molecules.
Define Induced Dipole
An induced dipole is a dipole that occurs in molecules with no permanent dipoles.
Electrons are still moving, therefore in particular moments electrons will not be distributed evenly across the two nuclei.
The difference in distribution of electrons in these moments creates a temporary dipole.
Define induced dipole - induced dipole force?
An induced dipole is a dipole that occurs in molecules with no permanent dipoles.
Electrons are still moving, therefore in particular moments electrons will not be distributed evenly across the two nuclei.
The difference in distribution of electrons in these moments creates a temporary dipole.
The positive temporary dipole of the molecule,attracts electrons toward it from neighbouring molecules.
This creates an induced negative dipole in the neighbouring molecule.
This process repeats, the second dipole induces the third and so on
These temporary dipoles are created and destroyed constantly due to motion of electrons, but this process is so rapid that the attraction between molecules remains.
Define Hydrogen Bond
Hydrogen bonds are intermolecular forces that occur when hydrogenbonds to the lone pairs in fluorine, oxygen or nitrogen
Which is the strongest intermolecular force?
hydrogen bonds
What increases the strength of induced dipole - induced dipole interactions?
The number of electrons - More electrons means greater fluctuation in movement around the nuclei.
This results in stronger temporary dipoles and therefore stronger forces between molecules.
What makes a molecular substance soluble?
-It is soluble if it can form hydrogen bonds to water
-The bigger the molecule the less effective hydrogen bonding is.
State VSEPR Theory
-The shape of the molecule is dependent upon the number of pairs of valence electrons in the central atom.
- Electrons - maximum distance minimum repulsion
Lone-pair / Lone pair repulsion is the greatest
Then lone-pair / bonding pair
Then bonding pair / bonding pair
How do lone pairs affect bond angle?
Reduce by 2.5 degrees
Shape and angle of 2 electrons pairs?
Linear - 180
3 electron pairs
Trigonal Planar - 120
4 electron pairs
Tetrahedral - 109.5
3 electron pairs - 1 lone pair
Trigonal Pyramidal - 107
2 electron pairs - 2 lone pairs
V-shaped
5 electron pairs
Trigonal Bipyramidal - 90 & 120
6 electron pairs
Octahedral - 90
