Example: biology

Periodic Trends in - profkatz.com

Periodic Trends inAtomic RadiiIonic RadiiParamagnetismIonization EnergyElectron AffinityMetallic CharacterShieldingIn a multi-electron system, electrons are simultaneously attracted to the nucleus and repelled by each electrons are shielded from nucleus by the core shielding causes the outer electrons to not experience the full strength of the nuclear Nuclear ChargeThe effective nuclear charge is the net positive charge that is attracting a particular is the nuclear chargeS is the number of electrons in lower energy levels Zeffective = Z S Electrons in same energy level contribute to screening, but very & Effective Nuclear ChargeTrend in Atomic Radius Main GroupThere are several methods for measuring the radius of an atom, and they give slightly different der Waals radius = nonbondingCovalent radius = bonding radiusAtomic radius as an average radius There is a General Trend: Atomic Radius Increases down group (top to bottom) Atomic Radius Decreases across period (left to right)Trend in Atomic Radius Main GroupQuantum-Mechanical Explanation for the Group Trend in Atomic RadiusThe size of an atom is related to the distance the valence electrons are from the larger the orbital an electron is in, the farther

Periodic Trends in Atomic Radii Ionic Radii Paramagnetism Ionization Energy Electron Affinity Metallic Character. Shielding In a multi-electron system, electrons are simultaneously attracted to the nucleus and repelled by each other. Outer electrons are shielded from nucleus

Tags:

  Trends, Periodic, Paramagnetism, Periodic trends in

Information

Domain:

Source:

Link to this page:

Please notify us if you found a problem with this document:

Other abuse

Transcription of Periodic Trends in - profkatz.com

1 Periodic Trends inAtomic RadiiIonic RadiiParamagnetismIonization EnergyElectron AffinityMetallic CharacterShieldingIn a multi-electron system, electrons are simultaneously attracted to the nucleus and repelled by each electrons are shielded from nucleus by the core shielding causes the outer electrons to not experience the full strength of the nuclear Nuclear ChargeThe effective nuclear charge is the net positive charge that is attracting a particular is the nuclear chargeS is the number of electrons in lower energy levels Zeffective = Z S Electrons in same energy level contribute to screening, but very & Effective Nuclear ChargeTrend in Atomic Radius Main GroupThere are several methods for measuring the radius of an atom, and they give slightly different der Waals radius = nonbondingCovalent radius = bonding radiusAtomic radius as an average radius There is a General Trend.

2 Atomic Radius Increases down group (top to bottom) Atomic Radius Decreases across period (left to right)Trend in Atomic Radius Main GroupQuantum-Mechanical Explanation for the Group Trend in Atomic RadiusThe size of an atom is related to the distance the valence electrons are from the larger the orbital an electron is in, the farther its most probable distance will be from the nucleus and the less attraction it will have for the down a group adds a principal energy larger the principal energy level an orbital is in, the larger its , quantum-mechanics predicts the atoms should get larger down a in Atomic Radius Quantum-Mechanical Explanation for the Period Trend in Atomic RadiusThe larger the effective nuclear charge an electron experiences, the stronger the attraction it will have for the stronger the attraction the valence electrons have for the nucleus.

3 The closer their average distance will be to the across a period increases the effective nuclear charge on the valence , quantum-mechanics predicts the atoms should get smaller across a Choose the Larger Atom in Each Pair N or F C or Ge N or Al Al or Ge C or O Li or K C or Al Se or ITrends in Atomic RadiusTransition MetalsAtoms in the same group increase in size down the radii of transition metals roughly the same size across the d nuclear charge by the ns2 electrons approximately the in Atomic Radius Main GroupElectron Configurations of Main Group Cations in Their Ground StateCations form when the atom loses electrons from the valence atom = 1s22s22p63s23p1Al3+ ion = 1s22s22p6 [Ne]The first electrons removed are the valence may also be removed from the sublevel closest to the valence shell after the valence iron atom has two valence electrons:Fe atom = 1s22s22p63s23p64s23d6 When iron forms a cation, it first loses its valence electrons:Fe2+ cation = 1s22s22p63s23p63d6 However, it can then lose 3d electrons.

4 Fe3+ cation = 1s22s22p63s23p63d5 Electron Configurations of Transition Metal Cations in Their Ground StateMagnetic Properties of Transition Metal Atoms & IonsElectron configurations that result in unpaired electrons mean that the atom or ion will have a net magnetic field this is called configurations that result in all paired electrons mean that the atom or ion will have no magnetic field this is called Illustrated(a) A sample (left side of balance) is weighed in the absence of a magnetic field. (b) When the field is turned on, the balanced condition is upset. The sample appears to gain weight. This is because it is now subjected to two attractive forces, the force of gravity and the force exerted by the magnetic Metal Atoms and Ions:Electron Configuration & Magnetic PropertiesBoth Zn atoms and Zn2+ ions are diamagnetic.

5 Zn atoms [Ar]4s23d10Zn2+ ions [Ar]4s03d10Ag forms both Ag+ ions and, rarely, Ag2+Ag atoms [Kr]5s14d10 are paramagneticAg+ ions [Kr]4d10 are diamagneticAg2+ ions [Kr]4d9 are paramagneticWrite the electron configuration and determine whether the Fe atom and Fe3+ ion are paramagnetic or Z = 26 Previous noble gas = Ar (18 electrons)4s 3d Fe atom = [Ar]4s23d6 Unpaired electrons Paramagnetic 4s 3d Fe3+ ion = [Ar]4s03d5 Unpaired electrons Paramagnetic Determine whether the following are paramagnetic or +Mn = [Ar]Sc = [Ar]4s23d1paramagnetic4s23d5 Sc3+ = [Ar] diamagneticTrends in Ionic RadiusIons from elements in same group have same size increases down the smaller than neutral larger than neutral isoelectric species, cations smaller than of the Group VIIA atoms (Halogens) and Their Anions Radii of Group IA Atoms and Their CationsRadii of Group IIA Atoms and Their CationsTrends in Ionic RadiusTrends in Ionic RadiusRadii of Metal Atoms andTheir CationsQuantum-Mechanical Explanation for the Trends in Cation RadiusWhen atoms form cations, the valence electrons are farthest electrons from the nucleus then are the p or d electrons in the (n 1) energy level.

6 This results in the cation being smaller than the remaining electrons also experience a larger effective nuclear charge , shrinking the ion even down a group, adds a new primary level, causing the cations to get to the right across a period, increases the effective nuclear charge for isoelectronic cations, causing the cations to get of Nonmetal Atoms andTheir AnionsWhen atoms form anions, electrons are added to the valence new outer electrons experience a smaller effective nuclear charge than the old valence electrons, increasing the result is that the anion is larger than the Explanation for the Trends in Anion RadiusMoving down a group, increases the n level, causing the anions to get to the right across a period, increases the effective nuclear charge for isoelectronic anions, causing the anions to get the larger of each pairS or S2 Ca or Ca2+ Br or KrS2 is larger because there are more electrons (18 e ) for the 16 protons to holdCa is larger because its valence shell has been lost from Ca2+the Br is larger because it has fewer protons (35 p+) to hold the 36 electrons than does Kr (36 p+)Order the following sets by size (smallest to largest)Zr4+, Ti4+, Hf4+Na+, Mg2+, F , NeI , Br , Ga3+, In+Ti4+ < Zr4+ < Hf4+Mg2+ < Na+ < Ne < F Ga3+ < In+ < Br < I Ionization EnergyMinimum energy needed to remove an electron from an atom or ionIonization EnergyMeasured in the gas stateAn endothermic processValence electron easiest to remove, lowest IEM(g) + IE1 M1+(g) + 1 e- M+1(g) + IE2 M2+(g)

7 + 1 e-1st IE energy = energy to remove electron from neutral atom2nd IE = energy to remove from 1+ ion; Trends in 1st Ionization EnergyThe larger the effective nuclear charge on the electron, the more energy it takes to remove farther the most probable distance the electron is from the nucleus, the less energy it takes to remove it. 1st IE decreases down the group. 1st IE generally increases across the Trends in 1st Ionization EnergyQuantum-Mechanical Explanation for the Trends in First Ionization EnergyThe strength of attraction is related to the most probable distance the valence electrons are from the nucleus and the effective nuclear charge the valence electrons larger the orbital an electron is in, the farther its most probable distance will be from the nucleus and the less attraction it will have for the , quantum-mechanics predicts the atom s first ionization energy should get lower down a across a period increases the effective nuclear charge on the valence.

8 Quantum-mechanics predicts the atom s first ionization energy should get larger across a the atom in each pair with the larger first ionization energy Al or S As or Sb N or Si O or Cl Mg or P Ag or Cu Ca or Rb P or SeTrends in Successive Ionization EnergiesRemoval of each successive electron costs more energy. 1)Shrinkage in size due to having more protons than electrons. 2) Outer electrons closer to the nucleus, therefore harder to increase in energy for each successive valence increase in energy when start removing core in Successive Ionization EnergiesElectron AffinityEnergy released when an neutral atom gains an electron in the gas state:M(g) + 1e M1 (g) + EADefined as exothermic ( ), but may actually be endothermic (+) (some alkali earth metals & all noble gases) The more energy that is released, the larger the electron more negative the number, the larger the EA.

9 Generally decreases down a column. Generally increases across EA in any period = halogenTrends in Electron AffinityElectron affinities of the main-group in Electron AffinityMeasured electron affinities for elements 1-57 and 72-86. A negative value means that energy is released when an electron adds to an atom, while a value of zero means that energy is absorbed but the exact amount can t be measured experimentally. Properties of Metals & NonmetalsMetalsmalleable & ductileshiny, lustrous, reflect lightconduct heat and electricitymost oxides basic and ionicform cations in solutionlose electrons in reactions oxidizedNonmetalsbrittle in solid statedull, non-reflective solid surfaceelectrical and thermal insulatorsmost oxides are acidic form anions in solutiongain electrons in reactions reducedMetallic CharacterMetallic character is how closely an element s properties match the ideal properties of a character decreases left-to-right across a character increases down the Explanation for the Trends in Metallic CharacterMetals generally have smaller first ionization energies and nonmetals generally have larger electron affinitiesexcept for the noble.

10 Quantum-mechanics predicts the atom s metallic character should increase down a column because the valence electrons are not held as strongly. Therefore, quantum-mechanics predicts the atom s metallic character should decrease across a period because the valence electrons are held more strongly and the electron affinity the more metallic element in each pair Sn or Te P or Sb Ge or In S or Br Mg or Al Si or Sn Br or Te Se or IAtomic Properties- Summary of Trends in the Periodic TableAtomic Properties- Summary of Trends in the Periodic TableAtomic Properties- Summary of Trends in the Periodic TableAtomic Properties- Summary of Trends in the Periodic TableTrends in the Alkali MetalsAtomic radius increases down the energy decreases down the low ionization reducing agents, easy to oxidizevery reactive, not found uncombined in naturereact with nonmetals to form saltscompounds generally soluble in water Electron affinity decreases down the point decreases down the very low MP for generally increases down the in the HalogensAtomic radius increases down the energy decreases down the high electron oxidizing agents, easy to reducevery reactive, not found uncombined in naturereact with metals to form saltscompounds generally soluble in water found in seawaterReactivity increases down the with hydrogen to form HX, point and boiling point increase down the increases down the between rubidium metal and liquid water: Rb(s) + H2O(l) ?


Related search queries