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Thermochemistry
Level 3 NCEA flsahcards
| Question | Answer |
|---|---|
| EN is..... | The measure of attraction an atom has for a pair of bonding electrons |
| IE is... | the minimium energy needed to remove an electron from an atom or ion in the gaseous state |
| AR is... | half the distance between the bonded nuclei |
| EN going across the periodic table... | Increases. |
| EN across the periodic table why... | becasue of the increasing number of protons so there is an increasing attration for electrons |
| IE going across the periodic table... | Increases |
| IE across the periodic table why... | becaue of the increasing attraction for electrons which means more energy is requied to remove them |
| AR going across the periodic table... | Decreases |
| AR across the periodic table why... | increasing attraction for electrons pulls the valance shell closer to the nucleus |
| EN going down the periodic table... | decreases |
| AR going down the periodic table why... | decreasing attraction for electrons so valance shell is further away from nucleus |
| EN going down the periodic table why... | increasing sheilding so there is a decrease in the attraction for electrons |
| IE going down the periodic table... | decreases |
| IE going down the periodic table why... | decreasing attraction for electrons so need less energy to remove them |
| AR going down the periodic table... | increases |
| Cations are what electrons | lost |
| anions are what electrons | gained |
| IR of positive ion | Fewer electrons are attracted more strongly to nucleus so IR is smaller than atom |
| IR of negitive ion | More electrons create more repultion betweeen elctrons so IR is bigger than atom |
| Pure covalent bond EN | 0-0.5 |
| Polar covalent bond EN | 0.6-1.5 |
| Ionic bond EN | 1.6+ |
| Forming anions | electrons are added into orbitals of increasing energy |
| Forming Cations | electrons are removed from 4s before 3d |
| [Ar] | 1s2,2s2,2p6,3s2,3p6 |
| Transition metals-Form complex ions | Central metal ion surrounded by ligands. Vacant 3d orbitals on t-metal ions accept these loan bonds |
| Transition metals-Form coloured compounds | Electrons in the incomplete 3d orbital absorb specific wave lengths of light energy. The colour seen is the light energy not absorbed |
| Transition metals-Make good catalysts | Vacant orbitals accept electron pairs from molecules. This strains the bonds in the molecules, encouraging reactions to occur |
| Lower oxidation states are | monatomic ions |
| Higher oxidation states | polyatomic ions |
| T metals lose 4s electrons and then a varying number of unpaired 3d electrons to give varying oxidation states | |
| 2 Linear | 2,180, symmetrical |
| Trigonal planar | 3, 120, symmetrical |
| 3 Angular bent | 3, 120, asymmetrical |
| Tetrahedral | 4, 109, symmetrical |
| Trigonal pyramidal | 4, 107, asymmetrical |
| 4 Angular bent | 4,104.5, asymmetrical |
| Linear | 4,109, asymmetrical |
| Trigonal bipyramidal | 5, 90, 120, symmetrical |
| Seesaw | 5, 90, 120, asymmetrical |
| T-shaped | 5, 90, 120, asymmetrical |
| 5 Linear | 5, 90, 120, symmetrical |
| Octahedral | 6, 90, symmetrical |
| Square-based pyramid | 6, 90, asymmetrical |
| Square planar | 6, 90, asymmetrical |
| Polar bond | unequally shared electrons between 2 atoms due to different EN |
| Polar molecule | has an uneven spread of charge |
| Non-polar bond | equally shared electrons between 2 identical atoms due to same EN |
| Non-polar molecule | even spread of charge |
| Intermolecular forces | forces within molecules or between ions |
| Examples of intermolecular forces | covalent bonds, ionic bonds |
| Covalent bonds | a strong attraction between atomic nuclei and shared pair of electrons. |
| Stronger covalent bonds | caused by more electrons being involved |
| Ionic bonding | strong EN attraction between cation and anion |
| Stronger ionic bonds | caused by higher charges |