The p-Block Elements | Unit 7 | Chemistry

The Nitrogen Family 1 belongs to 1st Group Element 15

The elements: Nitrogen (7N), Phosphorus (15P), Arsenic (33As), Antimony (51Sb), And bismuth (83Bi) are all found in group 15 of the Periodic Table.

The p-Block ElementsImportant points
  • The elements in this group can display a range of oxidation states, from -3 to +5.
  • Nitrogen has a maximum covalency of four because it lacks d-orbitals, which would allow it to expand its covalency.

The atomic (covalent) and ionic radii of the elements of the nitrogen family (group 15) are lower than the comparable elements of the carbon family (in a specific oxidation state) (group 14).

The covalent radius increases significantly from N to P. However, just a slight rise is shown from As to Bi.

Nitrogen exhibits a strong propensity


Elements in group 15 are more electronegative than those in group 14. From N to Bi, electronegativity becomes less and less positive.


All of the elements in group 15 can create MH3 gaseous hydrides.

(A) As we move along the group, the hydrides’ fundamental strength declines. NH3 is the strongest foundation as a result.

ASH3 > SbH3 > NH3 > PH3

(b) As atomic size rises, the thermal stability of the hydrides decreases.

Due to the lack of d-orbitals, N cannot form NX5. Bi cannot form a BiX5 because its 6s electrons are unwilling to participate in the construction of a bond.

Nitrogen can produce several oxides. The group’s remaining constituents, P, As, Sb, and Bi, combine to create E203 and E2o5, two different forms of oxides.

Group II Elements 16

The elements oxygen (8O), Sulphur (16S), Selenium (34Se), Tellurium (52Te), and Polonium (84Po) are all found in group 16 of the periodic table.

The valence shells of the elements have the electrical structure ns2np4. Due to its tiny size and high electronegativity, the first element of group 16 behaves chemically differently than the other group members.

As the number of shells rises, atomic and ionic radii increase from top to bottom.

As the group’s size increases, the ionisation enthalpy drops. In the relevant periods, group 16 elements have lower ionisation enthalpy values than group 15 elements. This is because group 15 elements’ half-filled p-orbital electronic structures are particularly stable.

Because oxygen atoms are more compact than sulphur atoms, oxygen has lower negative electron gain enthalpy.

Of all the elements, O has the second-highest electronegativity value after F. The group’s electronegativity declines as atomic number rises.

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As we move down the group, the tendency for catenation reduces.

All of the group’s constituent elements can form volatile hydrides.

  • From water to hydrogen sulphide, the volatility rises before falling.

Their boiling point makes this clear. H2S H2Se H2Te H2O is the order of the boiling temperatures of hydrides in ascending order. Down 27 the molecular weight increase causes the group boiling point to rise, increasing the van der Waal forces of 28 interaction. Due to hydrogen bonding, the b.p. of water is extremely high.

  • In decreasing order of thermal stability, the hydrides are H2O>H2S>H2Se>H2Te>H2Po.
  • The hydrides’ acidic strength increases in the following order: H2O, H2S, H2Se, and H2Te.

Group 16’s components all combine to generate binary halides.

  1. A number of oxo-acids are formed by S, Se, and Te. The most significant of S’s oxo-acids is sulfuric acid.
  2. Thiosulfiric acid (H2S2o3) and sulfuric acid (H2So3) cannot be isolated due to their instability. They can only be found in aqueous solutions or as their salts.
Group 17 elements in III

The elements fluorine (9F), chlorine (17Cl), bromine (35Br), iodine (53I), and astatine are all found in group 17 of the periodic table (55At).during their respective periods.

Although the earliest ionization energies are rather high, they get lower as the group progresses. Iodine can become an I+ ion by losing an electron.

The electronic arrangement for valence shells is ns2 np5.

Due to their maximal effective nuclear change, halogens have the shortest atomic radii 24. Cl > F > Br > I is a variation in electron affinities

The element known as F is the most electronegative one. Down the group, electronegativity declines. Agfents are well oxidised by halogens. The group has a drop in oxidising power.

  • The order of reactivity is F2 > Cl2 > Br2 > I2.
  • The M-X bond’s ionic character order is M-F>M-Cl>M-Br>M-I.
Hydrohalic acids range in strength as follows
  • HF, HCl, HBr, and HI
  • HCl, HBr, HI, and HF are in that sequence for B.P.
  1. Hypohalous acids are all weak acids and exist in solution only. Acid strength decreases down the group. HOCl > HOBr > HOI
  2. Acid strength increases as the number of O-atoms increases for a given halogen atom. HOCl < HClO2 < HClO3 < HClO4
IV Group 18 Elements: The Noble Gases
  • In group 18 of the Periodic table, elements helium (2He), neon (10Ne), argon (18Ar), krypton (36Kr), xenon (54Xe) and radon (86Rn) are present. They are collectively called as noble gases.
  • Noble gases are located at the end of each period. Their valence shell orbitals are fully occupied.
  • They are monoatomic and are sparingly soluble in water.
  • Xe forms fluorides XeF2, XeF4 and XeF6.
  • Xe03 has a square pyramidal structure, whereas XeOF4 has a trigonal pyramidal shape.

He is a non-flammable gas that is lighter than air and is used to inflate balloons for meteorological studies, according to usage 35.

Ar is employed to create an atmosphere that is inert

Physical Properties


Fluorine: Gases
Chlorine: Gases
Bromine: Liquid
Iodine: Solid
Astatine: Solid

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