斯坦福大学：“硅谷的核心”
斯坦福大学——“硅谷的核心” 很难讲是斯坦福成就了硅谷，还是硅谷成就了斯坦福。毫无疑问，如果没有硅谷，斯坦福今天最多不过是一所二流偏上的大学，但是，没有斯坦福，硅谷恐怕难以支撑他们长达半个世纪的繁荣。 ...
IB DP Chemistry: HL复习笔记15.2.1 Entropy
Entropy Entropy You may have wondered why it is that endothermic reactions occur at all, after all, what can be the driving force behind endothermic reactions if the products end up in a less stabl...
IB DP Chemistry: HL复习笔记15.1.5 Energy Changes in Aqueous Solutions
Measuring Energy Changes in the Lab Enthalpies of Solution Calorimetry can be used to find the energy change in chemical reactions. This is much easier to carry out in aqueous solutions We can take...
IB DP Chemistry: HL复习笔记15.1.4 Dissolution Energy Cycles
Dissolution Energy Cycles How are enthalpy of solution and hydration enthalpies related? The relationship between lattice enthalpy, hydration enthalpies and enthalpy of solution From the diagram we...
IB DP Chemistry: HL复习笔记15.1.3 Born-Haber Cycle Calculations
Born-Haber Cycle Calculations Once a Born-Haber cycle has been constructed, it is possible to calculate the lattice energy (ΔHlatꝋ) by applying Hess’s law and rearranging: ΔHfꝋ = ΔHatꝋ + ΔHatꝋ + IE...
IB DP Chemistry: HL复习笔记15.1.2 Born-Haber Cycles
Constructing Born-Haber Cycles A Born-Haber cycle is a specific application of Hess's Law for ionic compounds and enables us to calculate lattice enthalpy, which cannot be found by experiment The b...
IB DP Chemistry: HL复习笔记15.1.1 Key Enthalpy Terms
Key Enthalpy Terms Ionisation energy The ionisation energy (ΔHIEꝋ) is the standard enthalpy change that occurs on the removal of 1 mole of electrons from 1 mole of gaseous atoms or positively charg...
IB DP Chemistry: HL复习笔记14.2.3 Hybrid Orbitals
Hybrid Orbitals Hybridisation The ground state of the electrons in a carbon atom is 1s22s22p2 This can be represented using a spin diagram as shown: Orbital spin diagram for carbon in the ground st...
IB DP Chemistry: HL复习笔记14.2.2 Ozone Revisited
Ozone Revisited We have seen previously that ozone is a molecule with two resonance structures leading to a resonance hybrid The two Lewis resonance structures for ozone The central oxygen atom has...
IB DP Chemistry: HL复习笔记14.2.1 Delocalisation & Resonance
Delocalisation & Resonance The delocalisation of electrons can explain the structures of some species that don’t seem to fit with a Lewis structure Delocalised electrons are electrons in a mole...
IB DP Chemistry: HL复习笔记14.1.4 Formal Charge
Formal Charge A limitation of the model of covalent bonding is that when drawing Lewis structures for molecules, it is sometimes possible to come up with more than one structure while still obeying...
IB DP Chemistry: HL复习笔记14.1.3 Further VSEPR Theory
Further VSEPR Theory Revisiting Valence Shell Electron Pair Repulsion Theory (VSEPR) When an atom forms a covalent bond with another atom, the electrons in the different bonds and the non-bonding e...
