Questions On Chemistry

Submitted By annabellef
Words: 793
Pages: 4

6.4 * More energy for ionization step because harder to move negatively charged electron from a positively charged ion vs. neutral atom * ADD SOMETHING HERE * Easier to remove electron from partially filled valence shell because Zeff is lower, filled valence shell harder because Zeff is higher
* Electron Affinity, Eea, electron added to isolated atom in gaseous state * Ei always positive, Eea negative because energy is released to add electron * More negative Eea, greater tendency to accept electron and becomes more stable anion * Unstable anion accepting electron = positive Eea * 7A = negative Eea want to accept electron * 2A and 8A = near-zero or positive Eea because they are filled * Offset factors * Attraction between electron and nucleus = negative Eea * Electron-electron repulsion = positive Eea * Halogen Large negative Eea has a high Zeff and room for electron * Noble Gas Positive Eea has low Zeff because sublevels are full, electron goes to next shell * From filled s subshell to p subshell, high energy from p subshell will result Eea near zero * Low pull, high energy offset each other
* Element with small Ei transfer electron to element with negative Eea * Unfavourable when energy needed, no reaction * Energy change calculation * Convert atom into gaseous atom (positive energy) * Dissociation of gas into individual atoms (positive energy) * Ionization (positive energy) * Addition of electron (negative energy) * Formation of isolated atoms (negative energy) * Born-Haber cycle – pictorial format shows how steps contribute to overall energy change
* Lattice energy – electrostatic interaction energy between ions in solid * Lattice energy = positive break up ionic solid (energy absorbed) * Lattice energy = negative form ionic solid (energy released) * -U = force x distance (force=coulomb’s law) * Lattice energy = large when d is small and z1 and z2 are large * Compounds with same anion, diff cation = lattice energy increases as cation becomes smaller * Compounds with same cation, diff anion = lattice energy increases as anion becomes smaller * Higher charges, larger lattice energy
* Octet rule – main group elements react to attain noble gas configuration * Group 1A, 2A, 3A valence-shell electrons are shielded by core electrons, low Zeff and are lost easily * Group 6A and 7A valance-shell electrons poorly shielded, high Zeff, possible to gain electron * Strongly shielded; low Zeff; hard to add, easy to remove * Poorly shielded; low Zeff; hard to remove, easy to add
* Group 1A - smallest ionization energy, most powerful reducing agents * Electrolysis – electric current is passed through molten salt * electrical energy used to break down ionic compound into elements * K, Rb, Cs produced by chemical reduction (Reducing agent Na for K and Ca for Rb and CS) * React with 7A colorless crystalline ionic sas * Reactivity increases as Ei decreases * Reaction with oxygen * Lithium oxide * Sodium peroxide * The rest Super oxide * Reaction with water hydrogen gas + hydroxide
* Group 2A – first ionization energy larger and less reactive than alakali metals * Reactivity decreases going down * Produced by chemical reduction or electrolysis * React with 7A ionic halide salts * Reaction with oxygen oxide * Reaction of 2A and water, except Be hydroxides
* Group 7A – non metals and gain electron, large negative Eea and large positive Ei * Produced by oxidation