Periodic Relationships Among the Elements Chapter 8

주기율표 1. 주기율의 발견 2. 원소들의 주기적 분류 3. 물리적 성질의 주기적 변화 4. 이온화 에너지 5. 전자친화도 6. 주족 원소들의 화학적 성질의 변화

주기율의 발견 Dalton – Atoms will have different masses Newlands – Law of octaves

주기율의 발견 D. Mendeleev Arrange atoms with increasing masses To Be Discovered

Mendeleev 1.Arrange atoms with increasing masses. 2. Left blank for undiscovered elements.(Eb, Ea, Em, Es) 3. Corrected atomic masses for unfit data.

Eka-Al PropertyEkaaluminum(1871)Gallium(1875) atomic mass density (g/cm³) melting point (°C)Low29.78 oxide's formula Ea 2 O 3 (density g cm -3 ) (soluble in both alkalis and acids) Ga 2 O 3 (density g cm -3 ) (soluble in both alkalis and acids) chloride's formulaEa 2 Cl 6 (volatile)Ga 2 Cl 6 (volatile)

주기율의 발견

Sir William Ramsay, Lord Rayleigh at from the Greek word "argos“(inactive) Sir William Ramsay and by N. A. Langley and P. T. Cleve at from the Greek "helios“(sun) Sir William Ramsay, Morris W. Travers at from the Greek word "neon"(new) Sir William Ramsay, Morris W. Travers at from the Greek word "kryptos"(hidden)

주기율의 발견 -”inert gases” Lord Rayleigh ( ) and William Ramsey ( ) Ar, He, Ne, Kr, Xe In 1895 Rayleigh: the discovery of a new gaseous element argon. This element was chemically inert and did not fit any of the known periodic groups. Ramsey followed by discovering the remainder of the inert gases and positioning them in the periodic table Rayleigh (physics) and Ramsey (chemistry) were awarded Nobel prizes in The first inert gas compound was made in 1962 (XeF4) and many others.

주기율의 발견 Mosley – Atomic number

When the Elements Were Discovered

ns 1 ns 2 ns 2 np 1 ns 2 np 2 ns 2 np 3 ns 2 np 4 ns 2 np 5 ns 2 np 6 d1d1 d5d5 d 10 4f 5f Ground State Electron Configurations of the Elements

Classification of the Elements

Electron Configurations of Cations and Anions Na [Ne]3s 1 Na + [Ne] Ca [Ar]4s 2 Ca 2+ [Ar] Al [Ne]3s 2 3p 1 Al 3+ [Ne] Atoms lose electrons so that cation has a noble-gas outer electron configuration. H 1s 1 H - 1s 2 or [He] F 1s 2 2s 2 2p 5 F - 1s 2 2s 2 2p 6 or [Ne] O 1s 2 2s 2 2p 4 O 2- 1s 2 2s 2 2p 6 or [Ne] N 1s 2 2s 2 2p 3 N 3- 1s 2 2s 2 2p 6 or [Ne] Atoms gain electrons so that anion has a noble-gas outer electron configuration. Of Representative Elements

Cations and Anions Of Representative Elements

Na + : [Ne]Al 3+ : [Ne]F - : 1s 2 2s 2 2p 6 or [Ne] O 2- : 1s 2 2s 2 2p 6 or [Ne]N 3- : 1s 2 2s 2 2p 6 or [Ne] Na +, Al 3+, F -, O 2-, and N 3- are all isoelectronic with Ne Q. What neutral atom is isoelectronic with H - ? H - : 1s 2 same electron configuration as He

Electron Configurations of Cations of Transition Metals When a cation is formed from an atom of a transition metal, electrons are always removed first from the ns orbital and then from the (n – 1)d orbitals. Fe 2+ : [Ar]4s 0 3d 6 or [Ar]3d 6 Fe 3+ : [Ar]4s 0 3d 5 or [Ar]3d 5 Mn: [Ar]4s 2 3d 5 Mn 2+ : [Ar]4s 0 3d 5 or [Ar]3d 5 Fe: [Ar]4s 2 3d 6

Effective nuclear charge (Z eff ) is the “positive charge” felt by an electron. Na Mg Al Si Z eff Core Z Radius (pm) Z eff = Z -  0 <  < Z (  = shielding constant) Z eff  Z – number of inner or core electrons

Effective Nuclear Charge (Z eff ) increasing Z eff Roughly constant after an initial increase LiBeBCNOFNe NaMgA1SiPSClAr KCaGaGeAsSeBrKr RbSrInSnSbTeIXe CsBaTlPbBiPoAtRn Slater effective nuclear charges

Atomic Radius

Atomic Radii Li Na K Rb Cs Rn Xe Kr Ar Ne

Comparison of Atomic Radii with Ionic Radii

Cation is always smaller than atom from which it is formed. Anion is always larger than atom from which it is formed.

The Radii (in pm) of Ions of Familiar Elements

Chemistry in Action: The 3 rd Liquid Element? Liquid? 113 elements, 2 are liquids at 25 0 C – Br 2 and Hg 223 Fr, t 1/2 = 21 minutes Z (℃)

Ionization energy is the minimum energy (kJ/mol) required to remove an electron from a gaseous atom in its ground state. I 1 + X (g) X + (g) + e - I 2 + X + (g) X 2 + (g) + e - I 3 + X 2+ (g) X 3 + (g) + e - I 1 first ionization energy I 2 second ionization energy I 3 third ionization energy I 1 < I 2 < I 3

Variation of the First Ionization Energy with Atomic Number Filled n=1 shell Filled n=2 shell Filled n=3 shell Filled n=4 shell Filled n=5 shell

General Trend in First Ionization Energies Increasing First Ionization Energy

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

Variation of Electron Affinity With Atomic Number (H – Ba)

Diagonal Relationships Group-1Group-2Group-13Group-14 Second period LiBeBC Third period NaMgAlSi

Group 1(1A) Elements (ns 1, n  2) M M e - 2M (s) + 2H 2 O (l) 2MOH (aq) + H 2(g) 4M (s) + O 2(g) 2M 2 O (s) Increasing reactivity

Group 1(1A) Elements (ns 1, n  2)

Group 2(2A) Elements (ns 2, n  2) M M e - Be (s) + 2H 2 O (l) No Reaction Increasing reactivity Mg (s) + 2H 2 O (g) Mg(OH) 2(aq) + H 2(g) M (s) + 2H 2 O (l) M(OH) 2(aq) + H 2(g) M = Ca, Sr, or Ba

Group 2(2A) Elements (ns 2, n  2)

Group 13(3A) Elements (ns 2 np 1, n  2) 4Al (s) + 3O 2(g) 2Al 2 O 3(s) 2Al (s) + 6H + (aq) 2Al 3+ (aq) + 3H 2(g)

Group 13(3A) Elements (ns 2 np 1, n  2)

Group 14(4A) Elements (ns 2 np 2, n  2) Sn (s) + 2H + (aq) Sn 2+ (aq) + H 2 (g) Pb (s) + 2H + (aq) Pb 2+ (aq) + H 2 (g)

Group 14(4A) Elements (ns 2 np 2, n  2)

Group 15(5A) Elements (ns 2 np 3, n  2) N 2 O 5(s) + H 2 O (l) 2HNO 3(aq) P 4 O 10(s) + 6H 2 O (l) 4H 3 PO 4(aq)

Group 15(5A) Elements (ns 2 np 3, n  2)

Group 16(6A) Elements (ns 2 np 4, n  2) SO 3(g) + H 2 O (l) H 2 SO 4(aq)

Group 16(6A) Elements (ns 2 np 4, n  2)

Group 17(7A) Elements (ns 2 np 5, n  2) X + 1e - X - 1 X 2(g) + H 2(g) 2HX (g) Increasing reactivity

Group 17(7A) Elements (ns 2 np 5, n  2) Cl 2 Br 2 I2I2

Group 18(8A) Elements (ns 2 np 6, n  2) Completely filled ns and np subshells. Highest ionization energy of all elements. No tendency to accept extra electrons.

Properties of Oxides Across a Period basicacidic

Properties of Oxides Across a Period Na 2 OMgOAl 2 O 3 SiO 2 P 4 O 10 (or P 4 O 6 ) SO 3 (or SO 2 ) Cl 2 O 7 Adding H 2 O Na 2 O + H 2 O → 2NaOH MgO + H 2 O → Mg(OH) 2 Insoluble P 4 O H 2 O → 4H 3 PO 4 SO 3 + H 2 O → H 2 SO 4 Cl 2 O 7 + H 2 O→ HCl O 4 Adding HCl Na 2 O + H + → 2Na + + H 2 O MgO + 2H + → Mg 2+ + H 2 O Al 2 O 3 + 6H + → 2Al H 2 O No reaction No reaction No reaction No reaction Adding NaOH No reaction No reaction Al 2 O 3 + 2OH - + 3H 2 O → 2Al(OH) 4 - SiO 2 + 2OH - → SiO H 2 O P 4 O OH - → 4PO H 2 O SO 3 + OH - → SO H 2 O Cl 2 O 7 + OH - → 2ClO H 2 O Nature Basic AmphotericAcidicacidic

Chemistry in Action: Discovery of the Noble Gases Sir William Ramsay 1894 inactive 1895 sun 1898 new 1898 hidden 1898 strange

Slater's Rules for Effective Nuclear Charge Used to estimate effective nuclear charges [1s][2s2p][3s3p][3d][4s4p][4d][4f][5s5p][5d][5f]… All electrons to the right contribute 0 to shielding All electrons in the same group contribute 0.35 to shielding For s and p electrons, all electrons in the (n-1) shell contribute 0.85 each to the shielding All other electrons to the left contribute 1.0 to the shielding When considering [nd] or [nf] electrons, all electrons to the left contribute 1.0 to shielding Z eff = Z - 

Density of Solid