1.4 bonding Flashcards
Ionic bonding
One atom donates one or more electrons to another resulting in the formation of a cation and an anion.
Held together by electrostatic attraction from oppositely charged ions resulting in a solid lattice with high melting point.
Covalent bonding
a bond formed when atoms share one or more pairs of electrons.
It forms due to the electrostatic attraction between the positive nuclei of the bonded atoms and the negative electrons which are between the two nuclei.
Co-ordinate bond
Is a type of covalent bond where both electrons in the bond come from the same atom.
Why do ionic bonds have high melting and boiling points?
ionic compounds have have strong electrostatic attraction between oppositely charged ions which requires a lot of energy to break, thus have high melting points
bond polarity
a measure of how equally or unequally the electrons in any covalent bond are shared
intermolecular forces
Forces that occur between molecules
Intramolecular forces
Forces that occur within molecules.
Induced dipole-dipole interactions
The weakest type of intermolecular bond.
Created when electron distribution around a molecule is not symmetrical leading to a temporary dipole.
dipole-dipole interactions
(van der waals)
These occur between polar molecules and are exactly the same as the induced kind but dont rely on the fact that electrons move around.
Metallic bonding
a bond formed by the attraction between positively charged metal ions held in a lattice by delocalised electrons
hydrogen bonding
strong type of intermolecular dipole-dipole attraction.
Occurs between hydrogen and F, O or N atoms with the highest electronegativities and lone pairs.
Why are alcohols soluble in water
Alcohols form hydrogen bonds with the water molecules due to electronegative oxygen being bonded to a hydrogen in the OH group making them soluble in water.
How can electron pair repulsion theory predict shapes of simple molecules and ions
The shapes are determined by the arrangement of electrons around the central atom.
Electron pairs repel each other leading to specific shapes depending on how many electron pairs are present.
There’s higher repulsion between lone pairs then bonding pairs
effect of hydrogen bonding on boiling point in water
Hydrogen bonds form between the water molecules due to electronegative oxygen and the slightly positive hydrogen. These bonds require a lot of energy to break.
2 electron pairs
Linear
180*
Eg BeCl2
3 electron pairs
trigonal planar,
120 degrees
Eg bF3
4 electron pairs
tetrahedral,
109.5 degrees
Eg CH4
5 bonding pairs
trigonal bipyramidal
90, 120 degree angles
Eg PCL5
6 electron pairs
octahedral,
90 degrees
Eg SF6
Magnesium is a typical metal describe the bonding in magnesium and explain why it is ductile. (3)
Bonding in magnesium consist of metal ions surrounded by a sea of delocalised electrons (1)
electrostatic attraction between the ions and the electrons forms (1)
and when there is a force applied the layers of the metal ions over each other forming a new sheep and it is ductile because then it can be pulled or stretched into a shape. (1)
Describe the electrostatic attraction occurring in ionic bonds
In an ionic bond, there is an electrostatic attraction between two oppositely charged ions. In fact, the positive ions and negative ions are arranged so that each positive ion is surrounded by several negative ions and vice versa, to maximise the attractive forces and minimise the repulsive forces.
Describe the electrostatic attraction occurring in covalent and coordinate bonds
In a covalent (and coordinate) bond, there is a strong electrostatic attraction between the shared pair of electrons and the nuclei of both atoms. This outweighs the repulsion between the electrons in the shared pair. Also, both electrons in the bond have opposing spins to minimise this repulsion.
Define electronegativity
Electronegativity is the ability of an atom to attract the bonding electrons in a covalent bond.
Explain why Cl2 is a gas but I2 is a solid at room temperature
Chlorine, Cl2, has weak induced dipole-induced dipole forces between molecules and therefore it has a low boiling temperature. Although iodine, I2, also has induced dipole-induced dipole forces between molecules, it has more electrons (than chlorine). Therefore, the induced dipole-induced dipole forces are stronger and require more energy to break. This is why iodine, I2, has a higher melting temperature.
