Kîfa Dîtimîna Konfigurasyonê Elektronî ya Harkên Bigihînê
Electronic configuration of an atom is a way to describe how its electrons are arranged in different energy levels and sublevels around the nucleus. The electronic configuration of an atom determines many of its physical and chemical properties, such as how it reacts with other atoms, how it conducts electricity, and how it behaves in a magnetic field.
Electron çi ye?
Electron yek parçeyek subatomic e taybetandî ne ku ji navbera nukleyê tarî biceribin. Nukleyek di navber de protonên bi barzankî pozitîf û neutronan bi barzankî neutral da. Hejmarî protonan di nukleyê de hejmarî atomîk elementê belciyê, û hejmarî electronan di atomê neutral de hejmarê protonan bi tenê.
Electronan bi protonan û neutronan derbarê wateyên wekheviyên serbixwe yên di navber de hewce bike. Orbitan wekheviyên navendî yên ku electronan bi tevahî herî zafir dibînin. Navendan vê orbitan navendî yên din navendî yên orbitalan û subshellan dike, û wateyên û şeklên din dibe ku di rûni energy levelê de were.
Energy Level çi ye?
Energy level yek shell serekan û orbit e ku yek û du subshell û orbitalan da. Energy level î orbitala di navber de taybetandî ya wergera nukleyê: ji kêrher ku nêzîk be, energy yê vegirî; ji kêrher ku berd be, energy yê bikar.
Energy levels di navber de ji 1 derava 7 li ser navbera nukleyê tayin kirin. Yekêm energy level di navber de 2 electronan da, duyêm 8, sêyêm 18, û sija. Formula ji bo hesabkirina elektronên vegirîn di energy level de 2n^2 e, ku n energy level number e.
Subshell çi ye?
Subshell yek partî û energy level e ku yek û du orbitalan bi şekl û energy yekbûyî da. Subshellan bi hêrfên: s, p, d, f, g, û s., orbital quantum numbers 0, 1, 2, 3, 4, û s. Number of subshells in an energy level is equal to the energy level number: for example, the first energy level has one subshell (s), the second has two (s and p), the third has three (s, p, and d), and so on.
Maximum number of electrons that can fit in a subshell is given by the formula 2(2l + 1), where l is the orbital quantum number. For example, the s subshell can hold up to 2 electrons, the p subshell up to 6, the d subshell up to 10, and the f subshell up to 14.
Orbital çi ye?
Orbital yek region û space di subshell de ku electron bi tevahî herî zafir dibînin. Şekl û mezinahiya orbitalan di navber de energy level û subshell: for example, s orbitals are spherical, p orbitals are dumbbell-shaped, d orbitals are clover-shaped or complex-shaped, and f orbitals are even more complex.
Each orbital can hold up to 2 electrons with opposite spins: one spinning clockwise and one spinning counterclockwise. The spin is another property of electrons that affects their magnetic behavior.
How to Write the Electronic Configuration of an Atom?
The electronic configuration of an atom is written by listing all the occupied subshells with their number of electrons in superscript. For example, the electronic configuration of hydrogen (H) with one electron is 1s^1; the electronic configuration of helium (He) with two electrons is 1s^2; the electronic configuration of lithium (Li) with three electrons is 1s^2 2s^1; and so on.
The order in which the subshells are filled follows a rule called the Aufbau principle or building-up principle: electrons occupy the lowest-energy orbitals available first before moving to higher-energy ones.
How to Apply the Aufbau Principle?
To write the electronic configuration of an atom using the Aufbau principle, we need to follow these steps:
Start with the lowest-energy orbital, which is the 1s orbital, and fill it with up to two electrons.
Move to the next-lowest-energy orbital, which is the 2s orbital, and fill it with up to two electrons.
Move to the next-lowest-energy orbital, which is the 2p orbital, and fill it with up to six electrons.
Continue this process until all the electrons of the atom are assigned to orbitals.
To simplify the writing of electronic configurations, we can use a shorthand notation that uses the symbol of the previous noble gas in brackets to represent the inner electrons that are in a stable configuration. For example, instead of writing 1s^2 2s^2 2p^6 for neon (Ne), we can write [He] 2s^2 2p^6, where [He] represents the configuration of helium (He).
We can also use a diagram called an orbital diagram or an electron configuration diagram to show the distribution of electrons in orbitals using arrows or circles. The arrows represent the spin of the electrons, and they must be paired with opposite spins in each orbital. The circles represent the electrons without showing their spin.
What are the Exceptions to the Aufbau Principle?
The Aufbau principle works well for most elements, but there are some exceptions where electrons do not fill orbitals according to their energy levels. These exceptions occur because some atoms are more stable when they have half-filled or fully-filled subshells, especially in the d and f blocks.
For example, chromium (Cr) has an atomic number of 24, which means it has 24 electrons. According to the Aufbau principle, its electronic configuration should be [Ar] 4s^2 3d^4, where [Ar] represents the configuration of argon (Ar). However, this configuration is not very stable because the 3d subshell is only partially filled with four electrons. A more stable configuration is [Ar] 4s^1 3d^5, where both the 4s and 3d subshells are half-filled with one and five electrons, respectively.
Another example is copper (Cu), which has an atomic number of 29 and 29 electrons. According to the Aufbau principle, its electronic configuration should be [Ar] 4s^2 3d^9, where [Ar] represents the configuration of argon (Ar). However, this configuration is not very stable because the 3d subshell is only partially filled with nine electrons. A more stable configuration is [Ar] 4s^1 3d^10, where both the 4s and 3d subshells are fully filled with one and ten electrons, respectively.
There are other exceptions to the Aufbau principle in the transition metals (d block) and the lanthanides and actinides (f block). To identify these exceptions, we need to look at their observed electronic configurations and compare them with their predicted ones based on their energy levels.
Why is the Electronic Configuration of an Atom Important?
The electronic configuration of an atom is important because it determines many of its physical and chemical properties. For example:
The number of valence electrons, which are the electrons in the outermost shell or subshell, affects how an atom forms bonds with other atoms. Atoms tend to gain or lose electrons to achieve a stable configuration of eight valence electrons (or two for hydrogen and helium), which is called the octet rule. This rule explains why atoms form ions, covalent bonds, or metallic bonds.
The shape and orientation of orbitals affect how atoms form hybrid orbitals, which are combinations of orbitals that allow atoms to form bonds in different directions. For example, carbon can form four sp^3 hybrid orbitals that point toward the corners of a tetrahedron, or three sp^2 hybrid orbitals that point toward the corners of a triangle or two sp hybrid orbitals that point in opposite directions.
The type and number of hybrid orbitals depend on the number of valence electrons and the geometry of the molecule. For example, carbon can form four sp^3, three sp^2, or two sp hybrid orbitals depending on whether it is bonded to four, three, or two atoms, respectively.
The hybrid orbitals can overlap with other orbitals or hybrids on other atoms to form sigma bonds, which are strong covalent bonds that have cylindrical symmetry around the bond axis. For example, methane has four sigma bonds formed by the overlap of four sp^3 hybrids on carbon with four s orbitals on hydrogen.
The unhybridized p orbitals can overlap sideways with other p orbitals on adjacent atoms to form pi bonds, which are weaker covalent bonds
