Chemistry Chapter 1

• Long form of periodic table

  • Consists of seven horizontal rows known as periods and eighteen vertical columns known as groups
  • Two types of groups: Sub group A (representative elements) and Sub group B (transition elements)
  • Four blocks in the modern periodic table: s-block, p-block, d-block, and f-block
• 1. block

  • Located in the middle of the periodic table, covers all sub group B, general valence shell electronic configuration is ns², (n-1) d¹ to ns², (n-1) d¹0
• Periodic table


  A systematic arrangement of elements based on their atomic numbers, electronic configuration, and properties
• Regular changes in the physical properties of elements occur downward in the group and along the period in the long form of the periodic table, except for anomalies in certain places
• 1. block

  • Located on the extreme left in the periodic table, consists of groups IA and IIA, valence shell electronic configuration is ns¹ for alkali metals and ns² for alkaline earth metals
• Arrangement of elements in the periodic table

  According to their increasing atomic number and electronic configuration in a manner that correlates their general properties
• Identifying the position of an element in the periodic table

  By its electronic configuration: principal quantum number (n) of the valence electrons represents the period, while the group is predicted from the number of electrons in the valence shell
• 1. block

  • Located below the main body of the periodic table, exists in two horizontal series of fourteen elements each (lanthanides and actinides), valence configuration is ns¹,2, (n-2) f¹ to ns¹,2, (n-2) f¹4
• 1. block


  • Found on the extreme right of the periodic table, includes groups IIIA to VIIIA, valence shell electronic configuration of ns², np¹ to ns², np
• Elements in the periodic table exhibit a regular correlation of their general properties
• Group IIIA

  • Atomic radii generally increase down the group from boron to thallium
  • Exception to the trend between aluminum and gallium where gallium has slightly
• Elements of Group IA

  • Lithium
  • Sodium
  • Potassium
  • Rubidium
  • Cesium
  • Francium
• Group IIA

  • Beryllium is the smallest alkaline earth metal
  • Barium is the largest alkaline earth metal
• Group IA and IIA

  • Regular trend is down the group
  • Group trends due to the number of energy levels occupied by electrons
• Group IA

  • Elements are termed as alkali metals
  • They possess the largest atomic radii in their respective periods
  • Atomic radii increase regularly from lithium to francium due to an increase in the distance between the nucleus and the outermost electronic shell
• Atomic radius


  The distance between the nucleus of an atom to its outermost electron shell
• Atomic radii of Group IA and IIA in picometer (pm)

  • Li: 152
  • Na: 186
  • K: 227
  • Rb: 248
  • Cs: 265
  • Fr: 348
  • Be: 112
  • Mg: 145
  • Ca: 194
  • Sr: 219
  • Ba: 253
  • Ra: 215
• Group trend


  Regular variations in the properties of elements in a group of the periodic table
• Elements of Group IIA

  • Beryllium
  • Magnesium
  • Calcium
  • Strontium
  • Barium
  • Radium
• Reason for ionization energy decrease in Group IA and IIA

  Outermost electrons are located farther away from the nucleus as we go from top to bottom, leading to weaker attractive forces between the electrons and the nucleus
• Ionization energy trend in Group IA and IIA


  Decreases as we move down the group
• Groups IVA to VIIIA

  • IVA
  • VA
  • VIA
  • VIIA
• Gallium has a higher ionization energy than aluminum due to insufficient shielding of the nuclear charge by 3d electrons
• The atomic radii of elements of Group IVA to Group VIIIA increase regularly from top to bottom within the group
• Irregularities in ionization energy trend in Group IIIA elements occur as we move down the group
• Ionization Energy


  The energy needed to remove an electron from a neutral atom
• Poor shielding effect


  Caused by electrons of d-orbitals
• Elements in Group IVA to Group VIIIA


  • C
  • N
  • O
  • Si
  • Ge
  • Se
  • Sn
  • Pb
  • P
  • As
  • Sb
  • Bi
  • S
  • Se
  • Te
  • J
  • Po
  • F
  • Cl
  • Br
  • I
  • At
  • Na
  • Ar
  • Kr
  • Xe
  • Rn
• Elements located below aluminum have smaller atomic radii despite being located below it in the group
• Thallium exhibits a higher ionization energy than indium due to insufficient shielding of the nuclear charge by 4f electrons
• Gallium (Ga) has a higher ionization energy than aluminum (Al)


  Due to insufficient shielding of the nuclear charge in gallium by 3d electrons
• Thallium (TI) exhibits a higher ionization energy than indium (In)


  Due to insufficient shielding of the nuclear charge in thallium by 4f electrons
• The ionization energy of the remaining groups of representative elements follows a regular pattern, decreasing progressively from top to bottom as the atomic radii increase
• Irregularities observed between Tin (Sn) and Lead (Pb)


  Due to nearly the same atomic radii resulting from the lanthanide contraction, requiring more energy to remove electrons
• First ionization energies of representative elements in KJ/mol

  • Group IA: K (420), Rb (400), Cs (380)
  • Group IIA: Be (900), Mg (730), Ca (590), Sr (550), Ba (500)
  • Group IIIA: B (800), Al (577), Ga (580), In (560), TI (590)
  • Group IVA: Si (780), Ge (762), Sn (700), Pb (710)
  • Group VA: N (1400), P (1060), As (960), Sb (830), Bi (800)
  • Group VIA: O (1310), S (1001), Se (950), Te (870), Po (810)
  • Group VIIA: F (1680), Cl (1250), Br (1140), I (1010), At (920)
  • Group VIIIA: Ne (2080), Ar (1520), Kr (1350), Xe (1170), Rn (1030)
• The ionization energy of group IVA elements generally decreases from top to bottom in the group
• Electronegativity (EN)


  It is the measure of the tendency of an atom to attract the shared pair of electrons towards itself when it is involved in a covalent bond
• Electrical conductivity trends of representative elements

  • Alkali metals and alkaline earth metals generally exhibit high electrical conductivity
  • Group IIIA elements display moderate electrical conductivity
  • Elements in Group IVA can have variable conductivity ranging from poor to moderate
  • Group VA, VIA, and VIIA elements typically have poor electrical conductivity
  • Noble gases have extremely low electrical conductivity
• Electrical Conductivity


  Measurement of a material's capability to conduct electric current. It is a measure of how easily electric charges, such as electrons, can flow through a substance. Materials with high electrical conductivity allow electric current to pass through them easily, while materials with low electrical conductivity hinder the flow of electric charges
• The electronegativity (EN) of group III elements initially decreases from Boron (B) to Aluminum (Al) and then increases from gallium (Ga) to tellurium (Te). This irregular increase in EN can be attributed to the poor shielding effect of the electrons in the d-orbital and f-orbitals, respectively