Atomic Structure of Gallium
Gallium (Ga) is an element with an atomic number of 31. The atomic number, denoted by ‘Z’, specifies the number of protons found in the nucleus of every atom of an element. Therefore, a neutral gallium atom contains 31 protons. In a neutral atom, the number of electrons is equal to the number of protons. Thus, a neutral gallium atom also possesses 31 electrons.
The most common isotope of gallium is Gallium-69. The number 69 represents its mass number, which is the total count of protons and neutrons in the nucleus.
To determine the number of neutrons in Gallium-69: Number of Neutrons = Mass Number - Atomic Number Number of Neutrons = 69 - 31 = 38 neutrons.
Electron Configuration
The arrangement of electrons in the different energy shells and subshells around the nucleus is known as the electron configuration. For gallium, with 31 electrons, the configuration follows the Aufbau principle, Pauli exclusion principle, and Hund’s rule:
- Shell 1 (K shell): Holds 2 electrons in the 1s subshell (1s²)
- Shell 2 (L shell): Holds 8 electrons – 2 in 2s (2s²) and 6 in 2p (2p⁶)
- Shell 3 (M shell): Holds 18 electrons – 2 in 3s (3s²), 6 in 3p (3p⁶), and 10 in 3d (3d¹⁰)
- Shell 4 (N shell): Holds 3 electrons – 2 in 4s (4s²) and 1 in 4p (4p¹)
The complete electron configuration for gallium is: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p¹
Alternatively, using the noble gas notation, which simplifies the representation by using the configuration of the preceding noble gas (Argon, [Ar]): [Ar] 3d¹⁰ 4s² 4p¹
Valence Electrons
Valence electrons are the electrons located in the outermost occupied energy shell of an atom. These electrons are primarily involved in chemical bonding and determine an element’s chemical properties.
For gallium, the outermost occupied principal energy level is the 4th shell (n=4). In this shell, there are:
- 2 electrons in the 4s subshell (4s²)
- 1 electron in the 4p subshell (4p¹)
Therefore, gallium possesses a total of 2 + 1 = 3 valence electrons. This explains why gallium typically forms +3 ions in chemical reactions.
Properties and Applications
Gallium is a soft, silvery metal with an unusually low melting point, approximately 29.76 °C. This means it can melt even with the warmth of a human hand. It is not found as a free element in nature but as a compound in trace amounts in zinc ores and bauxite, the primary ore for aluminium, which is mined in states like Odisha and Andhra Pradesh in India.
One of gallium’s most significant applications is in the semiconductor industry, particularly in the form of gallium arsenide (GaAs). This compound is crucial for manufacturing high-frequency integrated circuits, light-emitting diodes (LEDs) used in display screens and lighting, and solar cells. These components are integral to modern electronics, including smartphones and computers widely used across Indian households and industries.