Thermo Chem Flashcards
Across a row
Ionisation energy increases
, due to increasing electrostatic attraction across a group
Down a group
Ionisation energy decreases, due to decreasing electrostatic attraction
Atomic radius across a row
Decreases, as electrons are pulled in closer due to electrostatic attraction
Atomic radius down a group
Increases as weaker electrostatic attraction, electrons aren’t pulled in close
Across group..
Protons increase, no change in shielding or distance
Down group
Number of protons but distance from nucleus increases and shielding increases
2 electron pairs, 1 bonded
Linear
2 pairs, 2 bonden
Linear 180
3, 1 bonded
Linear 180
3, 2 bonded
Bent 109.5
3,3 bonded
Trigonaal planar 120
4,1 bonded
Linear 180
4,2 bonded
Bent 109.5
4,3 bonded
Tribunal pyramidal 109.5
4,4
Tetrahedral 109.5
5,3
T shsped 90
5,4
Seesaw 120
5,5
Trigonal bipyramidal 120
6,4
Square planar 90
6,5
Square pyramid 90
6,6
Octahedral 90
Exothermic
Gives out heat, makes bonds -
Endothermic,
Requires heat, breaks bond +
Fusion
Solid- liquid
Vapourisation
Liquid gas
Sublimation
Solid to gas
Combustion
With oxygen
Entropy
Measure of disorder in system
Flat line represents
State change, temp is used to break bonds and stays same- as does kinetic energy
Climb in graph shows
Temp and kinetic energy increasing
+ve entropy
=Spontaneity
An - ion -affect on radius
Gains an electron, to become ion. This increases electron repulsion in valence energy level. Causes them to move further away so radius increases
Ionisation energy
The energy required to remove one mol of electrons from one mol of gaseous atoms
Electronegativity
Ability of an atom in a bond to attract electrons to itself
Common ion effect
Solubility of one salt is reduced by the presence of having another common ion
Buffer solution
Resists changes in ph when oh and h30 are added
Covalent bond
A shared pair of electrons, one electron being supplied by each atom- either side of the bond
Ionic bond
Oppositely charged ions held together by a crystal lattice by electrostatic attraction
Metallic bonding
Lattice of positive ions surrounded by delocalised electrons
Going down up group ionisation energy
Going up a group the number of energy levels decreases, as doe’s repulsion from inner energy levels. Valence electrons are closest to positive nucleus, this means there is a string electrostatic attraction between the positive nucleus and bonded valence shells- therefore most electronegative
Change in fusion enthalpy
Enthalpy change with 1 mol of substance is formed with its elements in standard state
Enthalpy combustion
Enthalpy change when one mol of substance is completely burned with oxygen
Atomic radius left to right
As the atomic number increases, so does the number of protons (therefore the positive charge in the nucleus). The electron shells are pulled in with more force, therefore there’s a strong electrostatic attraction between the positive nucleus and valence electrons. Therefore the atomic radius decreases
Atomic radius as you go down a group
The number of energy levels increase, and therefore the repulsion of the valence energy levels increase too. This causes the valence electrons to be further away from the nucleus and aren’t as strongly attracted by the increasing number of protons, so electrostatic attraction decreases and radius increases
Ionisation energy across a group
Increases as the number of protons increase, so there’s a greater nuclear charge attracting the orbiting electrons doing so strongly, therefore more energy is required to overcome this energy
Alcohol is it polar
Yes
Is a ketone/ aldehyde polar
Yss
Why is change in vap bigger than change in fusion
More heat energy is required to break all the attractive forces between liquid particles to form a gas. When a solid changes into a liquid, only some of the attractive forces are overcome, so less heat energy is required
