Konfigurasi Elektron ION- kimia SMA kelas 10 semester 1

Summary

In this video, the presenter explains the concept of electron configurations for ions, covering both positive (cation) and negative (anion) ions. They discuss how certain elements tend to lose or gain electrons, forming positive or negative ions. The video highlights how to write electron configurations for these ions, with specific examples like sodium (Na⁺) and magnesium (Mg²⁺). It also covers the distinct methods for elements in groups A and B of the periodic table, emphasizing the importance of understanding electron loss or gain based on the element's position in the periodic table. The video aims to clarify key concepts for learning ion configurations in chemistry.

Takeaways

• 😀 Ion refers to an atom or molecule with a charge, which can be either positive or negative.
• 😀 Metals (found in groups 1A, 2A, 3A, and transition metals) tend to lose electrons and form positive ions (cations).
• 😀 Non-metals (groups 5A, 6A, and 7A) are more likely to gain electrons and form negative ions (anions).
• 😀 Positive ions (cations) are formed when an atom loses one or more electrons, leading to a decrease in electron count.
• 😀 Example of a positive ion: Na (atomic number 11) loses one electron to become Na+ with 10 electrons, leading to a configuration of 1s² 2s² 2p⁶.
• 😀 Another example: Mg (atomic number 12) loses two electrons to become Mg²⁺ with 10 electrons, resulting in a configuration of 1s² 2s² 2p⁶.
• 😀 For transition metals (group B), we cannot simply subtract the number of electrons lost; we must consider their electron configuration more carefully.
• 😀 In the case of Sc (atomic number 21), it loses two electrons, but these electrons are removed from the outer 4s orbital, not the 3d orbital.
• 😀 For negative ions (anions), the atom gains electrons, which increases the electron count.
• 😀 Example of a negative ion: Sulfur (atomic number 16) gains two electrons to become S²⁻ with 18 electrons, resulting in a configuration of 1s² 2s² 2p⁶ 3s² 3p⁶.
• 😀 The key difference between positive and negative ions is that positive ions result from the loss of electrons, while negative ions result from the gain of electrons.

Q & A

What is an ion, and how does it form?

An ion is an atom or molecule that has gained or lost one or more electrons, resulting in a net electrical charge. Ions form when atoms either lose electrons (forming positive ions or cations) or gain electrons (forming negative ions or anions).

How do metals and non-metals differ in terms of ion formation?

Metals, which are electropositive, tend to lose electrons and form positive ions (cations). Non-metals, which are electronegative, tend to gain electrons and form negative ions (anions).

What are the groups of elements that typically form positive ions?

Elements in groups 1A, 2A, 3A, and the transition metals (group B) are more likely to lose electrons and form positive ions.

What is the process for writing the electron configuration of a positive ion?

To write the electron configuration of a positive ion, you subtract the number of electrons the ion has lost from the electron configuration of the neutral atom. The electrons lost are usually the outermost electrons (valence electrons).

How would you write the electron configuration for a Na+ ion?

For Na (atomic number 11), its neutral electron configuration is 1s2 2s2 2p6 3s1. When it forms Na+, it loses one electron from the 3s orbital. The electron configuration for Na+ is 1s2 2s2 2p6.

How do you write the electron configuration of Mg2+?

For Mg (atomic number 12), its neutral electron configuration is 1s2 2s2 2p6 3s2. When it forms Mg2+, it loses two electrons from the 3s orbital. The electron configuration of Mg2+ is 1s2 2s2 2p6.

Why do we not subtract electrons from the electron configuration when dealing with transition metals (group B)?

For transition metals, the electron configuration is more complex, and simply subtracting the number of electrons would lead to an incorrect configuration. Transition metals tend to lose electrons from the highest energy orbital (often the 4s orbital) rather than following the simple subtraction method used for main group elements.

How do you determine which electrons are lost when a transition metal forms a positive ion?

In transition metals, the electrons lost are always from the orbital with the highest principal quantum number (n). For example, for Sc (Scandium, atomic number 21), when it forms Sc2+, it loses electrons from the 4s orbital rather than the 3d orbital, as the 4s orbital has the highest n value.

How do you write the electron configuration for an anion?

To write the electron configuration of an anion, you add the number of electrons the ion has gained to the configuration of the neutral atom. For example, for S (atomic number 16), its neutral configuration is 1s2 2s2 2p6 3s2 3p4. When it forms S2-, it gains two electrons, and the electron configuration becomes 1s2 2s2 2p6 3s2 3p6.

What happens to the number of electrons when an atom becomes an ion?

When an atom forms a positive ion (cation), it loses electrons, which decreases the total number of electrons. When it forms a negative ion (anion), it gains electrons, increasing the total number of electrons.