Electron Bonding, Structure, Polarity Flashcards
How to write an ionic equation?
- Write out equation with charges
- Cross out repeating aspects
- You have your equation
Oxidation Numbers
Elemental form-0 Group 1- +1 Group 2- +2 Group 7- -1 Hydrogen- +1 Oxygen- -2
Oxidation numbers (exceptions)
Metal hydrides, hydrogen- -1
Peroxides, oxygen- -1
Oxygen bonded to fluorine, oxygen- +2
How to calculate the oxidation number
Sum of oxidation numbers=Total charge
1) Take oxidation number you know
2) Write into equation
3) Rearrange equation
4) This will give you oxidation number
Calculation oxidation number example
NO3 (3xO) + N = -1 (3x-2)+N= -1 -6 +N= -1 Therefore N=+5
What is OILRIG?
Oxidation is loss
Reduction is gain
What is the s sub shell?
Can hold a max of 2 electrons as each s sub shell has only 1 orbital
S orbitals are spherical
What is the p sub shell?
Can hold a max of 6 electrons as each sub shell has 3 orbitals
P orbitals are dumbbell shaped
What is the d sub shell?
Has 5 orbitals and can hold up to 10 electrons
What is the f sub shell
Has 7 orbitals so can hold up to 14 electrons
What is an orbital?
A 3D region of space around the nucleus that can hold a maximum of 2 electrons
How many electrons can shell 1 hold?
2 electrons
How many electrons can shell 2 hold?
8 electrons
How many electrons can shell 3 hold?
18 electrons
How many electrons can shell 4 hold?
32
What is the rule for how many electrons a shell can hold?
2n^2
What is the order of sub shell notation?
1s
2s 2p
3s 3p 3d
4s 4p 4d 4f
What is the rule of 4s and 3d?
Count 4s first but write it AFTER 3d
What is the electrons in box model?
Each box has an up and down electron represented as an arrow
Boxes should be filled singly first before doubling them up
What is the sub shell notation for Chromium
1s2 2s2 2p6 3s2 3p6 3d5 4s1
What is the sub shell notation for Copper?
1s2 2s2 2p6 3s2 3p6 3d10 4s1
What happens when d block elements form ions?
They lose 4S electrons FIRST
LINEAR
Shape: Linear
Bond Angle: 180*
Bond pairs: 2
Lone pairs: 0
TRIAGONAL PLANAR
Shape:Triagonal Planar
Bond angle: 120*
Bond pairs: 3
Lone pairs: 0
TETRAHEDRAL
Shape: Tetrahedral
Bond angle: 109.5*
Bond pairs: 4
Lone pairs: 0
TRIAGONAL BIPYRAMIDAL
Shape: Triagonal bipyramidal
Bond angle: 120* and 90*
Bond pairs: 5
Lone pairs: 0
OCTAHEDRAL
Shape: Octahedral
Bond angle: 90*
Bond pairs: 6
Lone pairs: 0
PYRAMIDAL
Shape: Pyramidal
Bond angle: 107*
Bond pairs: 3
Lone pairs: 1
NON-LINEAR
Shape: Non-Linear
Bond angle: 104.5*
Bond pairs: 2
Lone pairs: 2
SQAURE PLANAR
Shape: Square Planar
Bond angle: 90*
Bond pairs: 4
Lone pairs: 2
How work out shape of molecule
1) Use dot and cross diagram to work out total no. of electron pairs
2) Find regular/irregular shape based of the information of bond and lone pairs.
What is electronegativity?
The ability of an atom to attract the bonding electrons in a covalent bond
Electronegativity with different atoms
- More electronegative atom will have a greater share of electrons
- It is a polar molecule
Electronegativity with the same atom
- Electrons are shared equally
- Non-polar molecule
Electronegativity with very different atoms
- Increasing polarisation will turn the bond from covalent from ionic
- Most electronegative atom takes electrons completely, turning the bond from covalent to ionic
What is the electronegativity trend across the periodic table?
Electronegativity increases up and group and across a period
What are the electronegativity difference values on the Pauling Scale?
Covalent - 0
Polar covalent - 0-1.8
Ionic - >1.8
How does symmetry affect the polarity of a molecule?
Symmetry will cancel out any dipoles, causing the molecules to be non-polar
How to work out the dipole of a molecule?
1) Work out shape
2) Assign dipoles
3) Work out symmetry
4) Work out overall dipole
What is the structure of ice?
- Diamond-like structure
- Volume larger than liquid
How does water change at certain temperatures?
- 4*C < ice forms a simple molecular lattice
- at 4*C water is at its maximum density
- when ice melts, its structure collapses
What bonds/forces are in simple molecular lattices?
- Covalent bonds between atoms
- Weak intermolecular forces
What intermolecular forces does water have?
Hydrogen bonding
Why does water have hydrogen bonding?
There is a lone pair on an oxygen atoms that attracts the hydrogen bond
What is the trend for boiling point in group 18?
Down group 18, the boiling point increases
What is the trend of boiling point in group 14?
Down group 14, the boiling point increases
What are the intermolecular forces in order of strength? (strongest at top)
- Hydrogen bonding
- Permanent dipole-dipole interactions
- London forces (induced dipole)
What are permanent dipole-dipole interactions?
- Weak attractive force between permanent dipole dipoles
- Forces get stronger when electronegativity difference is higher (dipoles are larger)
How does London forces form?
- There is an uneven distribution of electrons
- Which creates an instantaneous dipole when electrons get close
- Which causes induced dipoles in neighbouring molecules
When do London forces get stronger?
- When the atom has more electrons
- Greater inst. dipole, ind. dipole larger, electrostatic attraction greater
What are the requirements for hydrogen bonding?
- Hydrogen must be bonded to a N, F or O
- Must have a lone pair on N, F or O
What causes ‘irregular shape molecule’ to have its shape?
- Comment on bonding pairs and lone pairs
- Comment on bonding angle
- Comment that lone pair repels MORE than bonding pair
What causes ‘regular shape molecule’ to have its shape?
- Comment on bonding pairs and lone pairs (none)
- Comment on bond angle
- Comment that bonding pair repels
Why are polar solvents miscible in water?
- Negative ions attracted to partially positive hydrogen atoms and positive ions attracted to partially negative oxygen atoms
- Ionic lattice breaks down as it dissolves
- Water molecules surround the ions
What is the solubility of non-polar simple molecules?
- Tend to be soluble in non-polar solvents as interactions occur between the molecule and the solvent
- Interaction weaken the intermolecular forces in the simple molecular lattice and force it to break down and the compound dissolves
Why are non-polar simple molecules typically not soluble in polar solvents?
- Very little interaction between molecules in lattice and molecules in solvent
- Intermolecular bonding within solvent is too strong to be broken
Why can iconic compounds conduct electricity when molten and aqueous but not when solid?
Because the ions are mobile and therefore can carry a charge
Why can metal conduct electricity in any state?
- When molten, ions are mobile
- When solid, delocalised electrons can carry a charge
