Chapter 8: Periodic Properties of Elements- Periodic property is properties that can be predicted based on the position of an element in the periodic table.8.2 Development of Periodic Table- Johann Dobereiner first attempted to organize element by grouping it into triads of similar properties.- John Newlands proposed an organization of element in octaves where every 8th element had similar properties.- Dmitri Mendeleev created modern periodic table that arrange elements in increasing mass and every column of table contain elements of similar properties.- Arrangement predicted existence of elements that has not been discovered yet.- Henry Mosley later, after Mendeleev, proposed listing elements according to atomic number to account for some inconsistencies that resulted from organizing based on mass.- Quantum-mechanical theory explain periodic law.8.3 Electron Configuration- Quantum-mechanic theory describe behavior of electrons in atoms.- Electron configuration show the orbitals electrons occupy.- Ground state is the lowest energy state that electrons occupy.- Electrons occupy the lowest energy orbitals first.- Electron spin is a property of electrons that affect the number of electron allowed in one orbital.- Sublevel energy splitting determine order of which electron fills orbital in a level.Electron Spin and Pauli Exclusion Principle- Orbital diagram is used to represent electron configuration.- The arrow of electron in orbital diagram represent electron’s spin.- Spin up (+0.5) is upward arrow and spin down (-0.5) is downward arrow.- Pauli exclusion principle is no two electrons in an atom can have the same four quantum numbers.- Each orbital can only have two electrons with opposite spins.Sublevel Energy Splitting- If energy level is empty of electrons at ground state of atom, then it is degenerate (all have same energy).- Orbitals split according to l values. The lower the value of l, the lower the value of energy of corresponding orbital.- s < p < d < f- Coulomb’s law state that potential energy of two charge particles depend on their charge and separation.- Two like charges repel and have positive potential energy.- Two opposite charges attract and have negative potential energy.- Shielding is when an electron experience positive charge of nucleus and negative charge of other electrons.- Inner electron shield outer electron from experiencing full nuclear charge.- Penetration is when a valence electron penetrates into a region occupied by inner electrons.- Greater penetration result in lower energy.Electron Configuration of Multielectron Atoms- Aufbau principle is filling up the orbital with electrons from lowest energy first.- Hund’s rule is when filling degenerate orbitals, electrons fill up singly with parallel spins first.- Lower repulsion between electrons and therefore more stable.- s sublevel has one orbital and 2 electrons.- p sublevel has three orbitals and 6 electrons.- d sublevel has five orbitals and 10 electrons.- f sublevel has seven orbitals and 14 electrons.8.4 Electron Configurations, Valence Electrons, and Periodic Table- Valence electrons are electrons in the outermost principal energy level.- Chemical property of element depend on valence electrons.- Elements in a column of periodic table have similar chemical properties because they have the same number of valence electrons.- Core electrons are the inner electrons of an element. All electrons that are not valence electrons.Orbital Blocks in Periodic Table- Alkali metals and alkaline earth metals are elements that fill the s sublevel.- Transition metals fill the d sublevel.- Group 13-18 elements excluding helium fill the p sublevel.- Lanthanides and actinides fill the f sublevel.- Total columns of each category/block corresponds to maximum number of electrons for that sublevel.- Row number of element is its highest principal level.Electron Configuration from Position- Use the preceding noble gas to shorten inner electron configuration.- The principal quantum number for d-block is n-1 (row number minus one).- This is because s sublevel of next principal level is lower than the d sublevel.- There are electron configuration exceptions for transition metals because s sublevel and d sublevel are very close in energy.- Chromium is 4s1d5 and Cu is 4s1 3d10. This is because a half filled d orbital and full d orbital produces more stability.- The principal quantum number for f-block is n-2.8.6 Periodic Trend in the Size of Atoms and Effective Nuclear Charge- Volume of atom is taken up primarily by the electrons.- Atomic radii are the average bonding radii.- Atomic radius is smaller than van der Waals radius (radius of atom when not bonded).- Bond length of two covalently bonded atoms is the sum of both atomic radii.- Atomic radii has the same trend as van der Waals radii.- Down a column of periodic table, atomic radius increase, and move across a row, atomic radius decrease.- Increase down column because principal quantum number increase. Valence electrons occupy larger orbitals.- Decrease across row because of effective nuclear charge and shielding.Effective Nuclear Charge- Atomic radius is determined by pull of nucleus on valence electrons.- Effective nuclear charge is the average charge/attraction to nucleus felt by a valence electron.- As elements move across row of periodic table, protons (positive charge of nucleus) increase but principal energy level remains the same.- Effective nuclear charge = Actual nuclear charge - Charge screened by inner electrons.- The higher the effective nuclear charge, the more tightly the nucleus can hold onto valence electron.- Transition metals do not follow general trend for atomic radii as it moves across row because radii stays relatively constant.- Because the principal quantum number for d orbitals are n-1. As proton is added, so is an inner electron.8.7 Ions: Electron Configurations, Magnetic Properties, Ionic Radii, and Ionization EnergyElectron Configurations and Magnetic Properties of Ions- Anion is adding electron to the highest energy orbital.- Cation is removing electrons from highest energy orbital.- For transition metals, electron is removed from highest n-value orbital first regardless if the d orbital have higher energy. (remove from s before d)- Remove valence electrons first.- Atom or ion that contains unpaired electrons is paramagnetic.- Diamagnetic is an ion or atom where all electrons are paired.Ionic Radii- Cation become significantly smaller than