Nickel (Ni) Revision Guide

Atomic Model of Nickel (Ni)

Nickel (Ni) is a transition metal located in Group 10 and Period 4 of the periodic table.

Atomic Number (Z): 28
- Number of Protons: 28
- Number of Electrons: 28 (in a neutral atom)
Atomic Mass (A): Approximately 58.69 u (atomic mass units)
Number of Neutrons: The most abundant isotope, Nickel-58 (⁵⁸Ni), has 30 neutrons (58 - 28). The average atomic mass accounts for other isotopes like ⁶⁰Ni (32 neutrons).
Atomic Size (Metallic Radius): Approximately 124 picometers (pm).

The ground state electronic configuration of Nickel is: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁸ 4s²

This can also be written using the noble gas core notation: [Ar] 3d⁸ 4s²

The electrons are distributed in the principal energy shells (K, L, M, N) as follows:

This distribution ensures a total of 28 electrons for a neutral Nickel atom. The partially filled 3d subshell is characteristic of transition metals.

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

First Ionization Enthalpy (IE₁): 737 kJ/mol
Second Ionization Enthalpy (IE₂): 1753 kJ/mol
Trend: Nickel’s ionization enthalpies are moderate, typical for transition metals. IE₁ is lower than non-metals and higher than alkali metals in the same period. IE₂ is significantly higher due to increased effective nuclear charge on the remaining electrons.

Electronegativity is a measure of an atom’s ability to attract shared electrons in a chemical bond.

Pauling Scale Electronegativity: 1.91
Trend: Nickel has a moderate electronegativity, indicating its ability to form polar covalent bonds but also to readily participate in metallic bonding.

Electron gain enthalpy is the energy change when an electron is added to a neutral gaseous atom to form a negative ion.

Electron Gain Enthalpy (E_ea): -112 kJ/mol
Trend: Nickel has a negative electron gain enthalpy, meaning it releases energy when it gains an electron. However, this value is not as strongly negative as for halogens, indicating it does not readily form stable anions.

Atomic radius is the size of an atom. For metals, the metallic radius is typically considered.

Metallic Radius: 124 pm
Trend: Within a period, atomic radius generally decreases from left to right due to increasing effective nuclear charge. However, among transition metals, the trend is more complex, often showing a slight decrease followed by a slight increase or relative constancy. Nickel’s atomic radius is typical for the 3d series transition metals.

Density: 8.90 g/cm³ at 20 °C
State at Room Temperature (25 °C): Solid
Color: Silvery-white with a slight golden tinge, high luster.
Melting Point: 1455 °C
Boiling Point: 2913 °C
Magnetic Properties: Ferromagnetic (strong attraction to magnetic fields) at room temperature.
Malleability and Ductility: Highly malleable (can be hammered into sheets) and ductile (can be drawn into wires).
Conductivity: Good conductor of heat and electricity.