1 - Chemical Bonding and Structure Flashcards
What is meant by isoelectric?
Ions with the same electronic configuration - Such as Mg2+ and F-
What is evidence for ions?
The migration of ions during electrolysis
Define Ionic bonding
The strong electrostatic force of attraction between oppositely charged ions
What is the trend of Ionic radius down a group?
Increases down a group as the ions occupy more shells
Define covalent bonding
The strong electrostatic attraction between two nuclei and the shared pair of electrons between them.
Describe sigma bonds
End on overlaps of S-S orbitals or P-P orbitals
Describe Pie bonds
Side on overlaps of P-P orbitals
What is a dative covalent bond?
When an orbital with a lone pair of electrons shares both electrons to another atom. Example NH4
What is Bond length?
The distance between the nuclei of two atoms that are covalently bonded
What is the trend for bond length and bond strength and how do multiple bonds affect this
For similar bonds, the shorter the bond length the greater the bond strength. The more bonds (double or triple) makes the bond shorter. From Cl2-I2 the bond strength decreases as the bond length increases.
Do multiple bonds affect shapes of molecules?
No
What are the names and angles of the Shapes of Molecules?
2,0 - Linear - 180 3,0 - Trigonal planar - 120 4,0 - Tetrahedral - 109.5 5,0 - Trigonal bipyramidal - 90 and 120 6,0 - Hexagonal - 90 and 180 3,1 - Trigonal pyramidal - 107 2,2 - V-Shaped - 104.5
Define Electronegativity
The ability of an atom to attract the bonding pair of electrons in a covalent bond
Describe and explain the trend in electronegativity
Decreases down a group due to effective nuclear charge decreasing with the increase in atomic radii and shielding.
Increases across a period as effective nuclear charge increases due to increase in effective nuclear charge.
What is a polar bond and polar molecule?
A polar bond has a permanent dipole
A polar molecule is molecule with one or more polar bonds and unbalanced dipoles due to their shape.
What are London Forces?
Intermolecular forces of attraction between instantaneous dipoles and induced dipoles. They exist between all molecules and their strength is determined by the number of electrons and the number of contact points.
What are Permanent dipole forces?
Permanent dipole - Permanent dipole interactions - allows attraction and repulsion - overall effect is less than London Forces.
What are hydrogen bonds?
Intermolecular forces of attraction in a compound of hydrogen that is covalently bonded to N,O or F and there is a lone pair of electrons on an atom of N, O or F.
Explain the trend of boiling temperatures in the hydrogen halides.
The temperatures increase as the number of electrons increase and therefore the London Forces are stronger. HF is the highest however due to the presence of hydrogen bonding.
Why does water have anomalous properties?
It has a high melting and boiling point for its number of electrons and its solid is less dense than its liquid.
This is because each water molecule can form two hydrogen bonds on average, increasing its boiling point.
What is a solvent?
A substance that in which another substance can dissolve
What is a solute?
The substance that dissolves in a substance
How does water act as a solvent?
Ionic compounds are soluble in water, the water molecules surround the ions and form electrostatic attractions between them. This is hydration.
Water forms hydrogen bonds with alcohols as they have an OH group.
As the number of carbon atoms on an alcohol increases it becomes less soluble.
What is metallic bonding?
The strong electrostatic force of attraction between metal ions (cations) and the delocalised electrons. Solid metals have giant metallic lattice structures with a regular lattice surrounded by delocalised electrons.
Structure of Iodine
Diatomic molecule arranged in a simple molecular lattice and is attracted to itself with london forces.
Structure of Diamond and graphite
Giant covalent lattices
