P-Block Elements Formula - Meaning, Formulas, Properties

The P-Block Elements 13th and 14th group elements of the periodic table primarily include the boron (B, Al, Ga, In, Tl) and carbon (C, Si, Ge, Sn, Pb) families. While 13th group elements form trivalent compounds, 14th group elements are tetravalent, with varied metallic and non-metallic properties.

13th Group (Boron Family)

General electronic configuration:

[Noble gas] ns ² np ¹

Possible Oxidation States: +3 is the most common (like Al ³⁺⁾ However, for heavier elements like Tl, the +1 state can also be significant due to the inert pair effect.

Atomic Radius

Trend: Generally increases as we move down a group.

Reason: With each succeeding element in a group, an additional electron shell is added. This increases the size of the atom.

Boron is the smallest, and Thallium is the largest.

Atomic Radius: B < Al < Ga < In < Tl

Electronegativity (Pauling Scale)

Trend: Generally decreases as we move down a group.

Reason: Increased atomic size results in the outermost electrons being farther from the nucleus, leading to a weaker pull on other atoms' electrons.

Boron has the highest electronegativity and thallium has the lowest in this group.

Electronegativity: Tl < In < Ga < Al < B

Ionization Energy

Trend: Generally decreases as we move down a group.

Reason: As the atomic size increases, outermost electrons are farther from the nucleus and are less tightly held. It thus requires less energy to remove them.

Group 13: Boron has the highest ionization energy, while thallium has the lowest.

Ionization Energy: Tl < In < Ga < Al < B

Chemical Properties

Reaction with Oxygen (Formation of Oxides):

2B+3O ₂ ​ →2B ₂ O ₃ ​

4Al+3O ₂ ​ →2Al ₂ O ₃ ​

Reaction with Acids: Aluminum reacts with dilute acids to release hydrogen gas.

2Al+6HCl→2AlCl ₃ +3H ₂ ​

Reaction with Alkalis: Aluminum reacts with alkalis to form aluminates and hydrogen.

2Al+2NaOH+6H ₂ O→ 2Na[Al(OH) ₄ ]+3H ₂ ​

Formation of Halides:

2B+3Cl ₂ ​ →2BCl ₃ ​

2Al+3Cl ₂ ​ →2AlCl ₃

Also Check – Tungstic Acid formula

14th Group (Carbon Family)

General electronic configuration:

[Noble gas] ns ² np ²

Possible Oxidation States: +4 is the most common (e.g., C in CO ₂ or Si in SiO ₂ )

+2 state becomes more stable for the heavier elements in the group, especially for Sn and Pb, again due to the inert pair effect.

For example, Pb ²⁺ in PbO or Sn ²⁺ in SnO.

Atomic Radius of Group 14

Trend: Generally increases as we move down a group.

Reason: With each succeeding element in a group, an additional electron shell is added. This increases the size of the atom.

Carbon is the smallest, and lead is the largest.

Atomic Radius: C < Si < Ge < Sn < Pb

Also Check – Charles Law Formula

Electronegativity (Pauling Scale) of Group 14

Trend: Generally decreases as we move down a group.

Reason: Increased atomic size results in the outermost electrons being farther from the nucleus, leading to a weaker pull on other atoms' electrons.

Carbon has the highest electronegativity, and lead has the lowest.

Electronegativity: Pb < Sn < Ge < Si < C

Ionization Energy of Group 14

Trend: Generally decreases as we move down a group.

Reason: As the atomic size increases, outermost electrons are farther from the nucleus and are less tightly held. It thus requires less energy to remove them.

Carbon has the highest ionization energy, and lead has the lowest.

Ionization Energy: Pb < Sn < Ge < Si < C

Download PDF P-Block Elements Formula

Chemical Properties of Group 14

Reaction with Oxygen: Carbon forms carbon dioxide upon complete combustion: C+O ₂ ​ →CO ₂ ​

Silicon burns in oxygen to form silicon dioxide:

Si+O ₂ ​→SiO ₂ ​

Reaction with Hydrogen: Carbon forms methane with hydrogen:

4C+2H ₂ ​ →CH ₄ ​

Germanium can react with hydrogen under specific conditions to form germane: 4 Ge+2H ₂ ​ →GeH ₄ ​

Reaction with Halogens: Carbon reacts with chlorine to form carbon tetrachloride: 4C+2Cl ₂ →CCl ₄ ​

Silicon reacts with chlorine to form silicon tetrachloride:

4Si+2Cl ₂ →SiCl ₄ ​

Formation of Alkynes: Carbon in the form of acetylene:

2C+H ₂ ​ →C ₂ H ₂

Also Check – Elevation of Boiling Point Formula

Halides of Group 14

Carbon: Tetrahalides:

CCl ₄ ​(Carbon tetrachloride), CBr ₄ ​(Carbon tetrabromide), CI ₄ ​(Carbon tetraiodide)

Silicon: Tetrahalides:

SiCl ₄ ​(Silicon tetrachloride), SiBr ₄ ​(Silicon tetrabromide), SiI ₄ ​ (Silicon tetraiodide)

Germanium: Tetrahalides:

GeCl ₄ ​ (Germanium tetrachloride), GeBr ₄ ​ (Germanium tetrabromide)

Dihalides:

GeCl ₂ ​ (Germanium dichloride), GeBr ₂ ​ (Germanium dibromide)

Tin (Sn): Tetrahalides:

SnCl ₄ ​ (Tin(IV) chloride or stannic chloride), SnBr ₄ ​(Tin(IV) bromide)

Dihalides:

SnCl ₂ ​ (Tin(II) chloride or stannous chloride), SnBr ₂ ​(Tin(II) bromide)

Lead (Pb): Tetrahalides:

PbCl ₄ ​ (Lead(IV) chloride), PbBr ₄ ​(Lead(IV) bromide)

Dihalides:

PbCl ₂ ​ (Lead(II) chloride), PbBr ₂ ​(Lead(II) bromide)

Oxides of Group 14

Carbon: CO (Carbon monoxide) - Neutral oxide

CO ₂ (Carbon dioxide) - Acidic oxide

Silicon: SiO (Silicon monoxide) - It's less stable.

SiO ₂ ​ (Silicon dioxide or silica) - Acidic oxide

Germanium: GeO (Germanium monoxide) - Neutral oxide

GeO ₂ ​(Germanium dioxide) - Amphoteric oxide

Tin (Sn): SnO (Tin(II) oxide or stannous oxide) - Amphoteric oxide

SnO ₂ ​(Tin(IV) oxide or stannic oxide) - Amphoteric oxide

Lead (Pb): PbO (Lead(II) oxide or litharge) - Amphoteric oxide

PbO ₂ ​(Lead(IV) oxide or plattnerite) - Amphoteric oxide

Pb ₃ O ₄ ​(Lead(II, IV) oxide or red lead) - Mixed oxide