Electrons, Bonding and Structure Flashcards
How many electrons fill each shell?
1st shell - 2
2nd shell - 8
3rd shell - 18
4th shell - 32
Describe the energy levels of shells
Electrons further from the nucleus are in a higher energy state
the order of subshells is s, p, d and f
What are the shapes of the subshells
s - spherical
p - dumbbell
What are the max num of electrons in each sub-level
s - 2
p - 6
d - 10
f - 14
What are orbitals
regions of space that electrons are most likely to be in
What is the Aufbau Principle
Easier to sit downstairs than upstairs
- lower levels are filled before the higher levels
What is Hund’s rule
Prefer to sit on an empty seat than one with someone in it
- half fill the orbitals of the same energy with electrons of the same spin
What is Pauli’s Exclusion Principle
Electrons must have different spins
What is Ionic Bonding
The electrostatic attraction between positive and negative ions
Why do ions form
Because atoms gain or lose an electron to become isoelectronic with a noble gas
- noble gases have a full valance shells, making them stable
Why do Ions dissolve in water
Water is polar and so the positive ion is attracted to Oxygen and the negative ion is attracted to Hydrogen
What does isoelectronic mean
Same number of electrons
What is a covalent bond
The strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms
What are the properties of covalent
Low m.p and b.p - weak intermolecular forces
Good insulators - neutral and no free charge
Soluble in non-polar solvents
What is dative bonding
Occurs when an atom shares a lone pair of electrons to form a bond
What shape and angle would a bond with 2 bonding pairs and 0 lone pairs
Linear - 180 degrees
What shape and angle would a bond with 3 bonding pairs and 0 lone pairs
Trigonal planar - 120 degrees
What shape and angle would a bond with 4 bonding pairs and 0 lone pairs
Tetrahedral - 109.5 degrees
What shape and angle would a bond with 5 bonding pairs and 0 lone pairs
Trigonal Bipyramidal - 120 + 90 degrees
What shape and angle would a bond with 6 bonding pairs and 0 lone pairs
Octahedral - 90 degrees
What shape and angle would a bond with 2 bonding pairs and 1 lone pair
Non-linear - 117.5 degrees
What shape and angle would a bond with 2 bonding pairs and 2 lone pairs
Non linear - 104.5 degrees
What shape and angle would a bond with 3 bonding pairs and 1 lone pair
Pyramidal - 107
What shape and angle would a bond with 4 bonding pairs and 2 lone pairs
Square planar - 90 degrees
What is electronegativity
The ability of an atom to attract the bonding electrons in a covalent bond
What does a greater electronegativity mean
greater pull
What is the Pauling scale
The electronegativity scale that shows that electronegativity increases across a period and up a group
Why does electronegativity increase across a period
Increase in protons means a higher nuclear charge
Why does electronegativity increase up a group
Less electron sheiding
What are dipoles
Occur when electrons are shared unequally due to the electronegativity of an element
What are Polar molecules
Polar molecules occur if the bond dipoles can’t cancel out, thus giving the
overall molecule a dipole.
What are the 3 intermolecular forces
Permanent dipole-dipole interactions
Induced dipole-dipole interactions
Hydrogen bonding
What is Permanent Dipole-dipole interactions
The weak electrostatic attraction between two polar molecules
What is Induced Dipole-Dipole interaction
Happens in all molecules
Electrons move closer to one side of the electron, creating a δ– charge
This can then induce a dipole in another nearby molecule - instantaneous-induced dipole interaction
What is the order of intermolecular forces (strongest to weakest)
Hydrogen
Permanent dipole-dipole
Induced dipole-dipole
Simple molecule structure
simple molecular lattice with molecules arranged in a repeating pattern, held together by weak induced dipole-dipole forces
when heated the weak intermolecular forces are easily broken, allowing molecules to escape as gas
Which molecules undergo sublimation
CO2 and I2
What is hydrogen bonding
intermolecular bonding between molecules containin N,O or F and the H atom of -NH, -OH, or HF
What is needed for hydrogen bonding to occur
a lone pair of electrons
a hydrogen covalently bonded to a F, O or N atom
What are the anomalous properties of water
Less dense as a solid
Relatively high m.p. and b.p
Why is water less dense as a solid
Liquid water
– hydrogen bonds constantly broken and reformed.
Solid water
– molecules arranged in hexagonal rings to maximise the number of
stable hydrogen bonds.
- creating a larger volume
What is metallic bonding
Metal-metal bonds held together by strong electrostatic forces of attraction between delocalised electrons and positive ions
