2.2 ELECTRONS,BONDING & STRUCTURE Flashcards
State the number of electrons that can fill the first four shells
Shape of s-orbitals
- Spherical shape
Shape of p-orbitals
- 3D dumb-bell shape
How many electrons can an s-orbital hold?
2
How many electrons can a p-orbital hold?
6
How many electrons can a d-orbital hold?
10
Which shells contain s-orbitals?
- All shells
Which shells contain p-orbitals?
- From n=2 upwards
Which shells contain d-orbitals?
- From n=3 upwards
Does 4s or 3d have a higher energy level?
- 3d has a higher energy level so is filled first
Define ionic bonding
- The electrostatic attraction between positive and negative ions
Describe giant ionic lattice structure
- Repeating pattern of oppositely charged ions with strong electrostatic attraction in all directions
Explain the melting/boiling point of a giant ionic lattice
- Strong ionic bonds in all directions means lots of energy needed to overcome these bonds, so has a high mp/bp
Explain the electrical conductivity of a giant ionic lattice
- Giant ionic lattices can only conduct when melted/dissolved because ions are not mobile/cant move in the solid state
Explain the solubility of a giant ionic lattice
- Giant ionic lattices are soluble in polar solvents (e.g water) because polar water molecules can interact/break apart the ions
Define covalent bonding
- The strong electrostatic attraction between a shared pair of electrons and the nucleus of the bonded atoms
Define dative covalent bonding
- When one atom provides both of the shared electrons in a covalent bond
What type of bonding does average bond enthalpy measure?
- Covalent bond
Compare the relative repulsion strengths of bonded pairs of electrons and lone pairs of electrons
- Lone pair repulsion is greater than bonded pair repulsion
Draw the shape and bond angle of a linear molecule.
Draw the shape and bond angle of a non-linear molecule.
Draw the shape and bond angle of a trigonal planar molecule.
Draw the shape and bond angle of a pyramidal molecule.
Draw the shape and bond angle of a tetrahedral molecule.
Draw the shape and bond angle of a octahedral molecule.
Define electronegativity
- An atoms ability to attract the bonding electrons in a covalent bond
State the most electronegative element
- Fluorine
State and explain electronegativity across a period.
- Electronegativity increases
- Atomic charge (proton number) increases so there is a stronger attraction between nucleus and bonded electrons in a covalent bond
State and explain electronegativity up a group.
- Electronegativity increases
- Atomic radius decreases due to less shells so theres less electron sheilding
- Atomic radius decreases due to less shells so shorter distance between nucleus and bonded electrons in a covalent bond
- Therefore, stronger attraction
Define polar bond
- When a difference in electronegativitys causes a perminant dipole
State 2 requirements for a molecule to be polar.
1) Must have a polar bond (perminant dipole)
2) Must be assymetrical so dipoles dont cancel out
State the three types of intermolecular forces
1) London/induced temporary dipole-dipole forces
2) Perminant dipole-dipole forces
3) Hydrogen bonding
Which types of molecules have london/induced temporary dipole-dipole forces?
- ALL molecules
Which types of molecules have perminant dipole-dipole forces?
- Polar molecules
Which types of molecules have hydrogen bonding?
- Only molecules with H and O, N, F
Define hydrogen bonding
- A type of perminant dipole-dipole interaction between an electron deficient hydrogen (δ+) and a lone pair of electrons on O,F,N
State what the strength of London/induced temporary dipole-dipole forces depends on
- Number of electrons
- More electrons = stronger london forces
Draw hydrogen bonding between water molecules
Explain the 2 effects of hydrogen bonding on water properties
- Higher than expected MP/BP because of additional hydrogen bonding that requires more energy to overcome
- Ice is less dense than water because additional hydrogen bonding gives it an open lattice structure
Describe the solid structure of simple molecular lattices
- Covalent bonds between atoms
- Attracted by intermolecular forces (NAME IT)
Explain the electrical conductivity of simple molecular lattices
- Not conductive because there are no charged particles that are free to move
Explain the solubility of simple molecular lattices
- They are non-polar so only soluble in non-polar solvents as weak london forces can form between molecules and non-polar solvent to break apart the simple molecular lattice
Explain the MP/BP of simple molecular lattices
- Relatively low MP/BP because of relatively weak intermolecular forces (NAME IT) that do not require great amounts of energy to overcome
