Titanium (Ti): Atomic Structure & Chemical Properties

Atomic Model Details

Titanium (Ti) is a transition metal with the following fundamental atomic characteristics:

• Atomic Number (Z): 22
• Protons: 22 (Number of protons defines the element)
• Electrons: 22 (In a neutral Titanium atom)
• Neutrons: 26 (For the most abundant isotope, $^{48}$Ti, Mass Number A = 48)
• Atomic Mass: Approximately 47.867 u
• Atomic Size (Metallic Radius): 147 pm

Electronic Configuration & Shell Diagram

Titanium’s electronic configuration dictates its chemical behavior.

• Electronic Configuration: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d² 4s²
• Noble Gas Configuration: [Ar] 3d² 4s²
  • This configuration shows that Titanium has 2 electrons in its outermost 4s orbital and 2 electrons in the penultimate 3d orbital. The presence of partially filled d-orbitals is characteristic of transition metals.

Shell Diagram Representation (Textual)

A textual representation of electron distribution in shells for Ti (Z=22) is:

• K-shell (n=1): 2 electrons
• L-shell (n=2): 8 electrons
• M-shell (n=3): 10 electrons (2 from 3s, 6 from 3p, 2 from 3d)
• N-shell (n=4): 2 electrons (from 4s)

Periodic Trends

Ionization Enthalpy (IE)

Ionization enthalpy is the energy required to remove an electron from a gaseous atom.

• First Ionization Enthalpy (IE₁): 658 kJ/mol (Energy to remove the first 4s electron)
• Second Ionization Enthalpy (IE₂): 1310 kJ/mol (Energy to remove the second 4s electron)
• Third Ionization Enthalpy (IE₃): 2652 kJ/mol (Energy to remove the first 3d electron)
• Fourth Ionization Enthalpy (IE₄): 4175 kJ/mol (Energy to remove the second 3d electron)
• Trend: Ionization enthalpies generally increase across a period due to increasing effective nuclear charge and decrease down a group. For transition metals, the successive ionization enthalpies show a gradual increase as electrons are removed from 4s, then 3d orbitals.

Electronegativity

• Pauling Scale: 1.54
• Trend: Electronegativity generally increases across a period and decreases down a group. Titanium’s electronegativity is moderate, typical for a metal, indicating its tendency to lose electrons rather than gain them.

Electron Gain Enthalpy (ΔegH)

• Value: Small positive or near zero (~+7.6 kJ/mol)
• Trend: Electron gain enthalpy for metals, particularly transition metals, is typically positive or slightly negative, as they do not readily accept electrons to form stable anions. Titanium prefers to form cations by losing electrons.

Atomic Radius

• Metallic Radius: 147 pm
• Trend: Atomic radii generally decrease across a period due to increasing effective nuclear charge. For transition metals, there is an initial decrease, followed by a relatively constant range, and then a slight increase at the end of the series. Titanium, being at the beginning of the 3d series, has a relatively larger atomic radius compared to later 3d elements.

Key Physical Properties

Titanium is known for its excellent strength-to-weight ratio and corrosion resistance.

• Density: 4.506 g/cm³ (at 20 °C)
• State at Room Temperature (25 °C): Solid
• Color: Silvery-white metallic luster
• Melting Point: 1668 °C (1941 K)
• Boiling Point: 3287 °C (3560 K)
• Hardness: Relatively hard, scratchable by steel.
• Malleability/Ductility: Good malleability and ductility when pure, but becomes brittle with impurities like oxygen and nitrogen.