Chapter 8: Periodic Relationships Among the Elements Chemistry 1411 Joanna Sabey

Periodic Table

Periodic Table

Periodic Table An atom of a certain element has 15 electrons. Without consulting a periodic table, answer the following questions: 1) What is the ground-state electron configuration of the element? 2) Is the element diamagnetic or paramagnetic? 1) Write the configuration until the electrons add to 15: 1s2 2s2 2p6 3s2 3p3 2) The last set tells us if they are unpaired: The element is paramagnetic

Isoelectric Isoelectric: having the same number of electrons, the same electron configuration, as another element. Label the element the following ions are isolecetric to: Na+ Ne Ca2+ Ar F- O2- N3- Fe3+ V Mn2+

Effective Nuclear Charge Effective nuclear charge (Zeff): the nuclear charge felt by an electron when both the actual nuclear charge (Z) and the repulsive effects of the other electrons are taken into account.

Atomic Radius Atomic radius: one-half the distance between the two nuclei in two adjacent metal atoms or in a diatomic molecule

Atomic Radius Arrange the following elements in order of increasing radius: P, Si, N, O The trend of the radius is increases down the periodic table and to the left. O < N< P< Si

Ionic Radius Ionic Radius: the radius of a cation or an ion, usually measured by X-ray diffraction. Cation is always smaller than atom from which it is formed. Anion is always larger than atom from which it is formed.

Ionic Radius For each of the following pairs, indicate which one of the two species is larger: N3− or F- N3- Mg2+ or Ca2+ Ca2+ Fe2+ or Fe3+ Fe2+

Ionization Energy Ionization Energy: the minimum energy required to remove an electron from a gaseous atom in its ground state. I1 + X (g) X+(g) + e- I2 + X+(g) X2+(g) + e- I3 + X2+(g) X3+(g) + e-

Ionization Energy Increasing First Ionization Energy

Ionization Energy Which atom should have a smaller first ionization energy: oxygen or sulfur? Sulfur would have a smaller first ionization energy Which atom should have a higher first ionization energy: lithium or beryllium? Beryllium has the higher second ionization energy

Electron Affinity Electron Affinity: the negative of the energy change that occurs when an electron is accepted by an atom in the gaseous state to form and anion. F (g) + e- F-(g) DH = -328 kJ/mol EA = +328 kJ/mol O (g) + e- O-(g) DH = -141 kJ/mol EA = +141 kJ/mol

Chemical Properties Diagonal relationships: similarities between pairs of elements in different groups and periods of the periodic table.

Group 1A elements React the same way with water and Oxygen gas. 2M(s) + 2H2O(l) 2MOH(aq) + H2(g) 4M(s) + O2(g) 2M2O(s)

Group 2A Elements Calcium, strontium, and barium can react with cold water and acid. M(s) + 2H2O(l) M(OH)2(aq) + H2(g) M = Ca, Sr, or Ba Be(s) + 2H2O(l) No Reaction 2M(s) + O2(l)  2MO(s)

Group 3A 4M(s) + 3O2(g)  2M2O3(s) 2M(s) + 6H+(aq) 2M3+(aq) + 3H2(g)

Group 4A Elements For the metals, tin and lead, they react with acids. Sn(s) + 2H+(aq) Sn2+(aq) + H2 (g) Pb(s) + 2H+(aq) Pb2+(aq) + H2 (g)

Group 5A Elements N2O5(s) + H2O(l) 2HNO3(aq) P4O10(s) + 6H2O(l)  4H3PO4(aq)

Group 6A Elements All form 2- anions, and the important commercial suluar formation is sulfur trioxide and water mixture. SO3(g) + H2O(l)  H2SO4(aq)

Group 7A Elements All of the halogens come as diatomic molecules, X2, they react with hydrogen to form hydrogen halides. Reactivity increases as you go up the periodic table. X2(g) + H2(g)  2HX(g)

Group 8A Elements Completely filled ns and np subshells. Highest ionization energy of all elements. No tendency to accept extra electrons

Oxides Metal oxides are basic and nonmetal oxides are acidic. Amphoteric: display both acidic and basic properties. Classify the following oxides as acidic, basic, or amphoteric: Rb2O Basic BeO Amphoteric As2O5 Acidic Na2O MgO Al2O3 SiO2 P4O10 SO3 Cl2O7 Ionic Molecular Basic Amphoteric Acidic