S1.3.5 Electron configurations of ions

Summary

This video explores the electron configurations of ions, focusing on cations like sodium, magnesium, and aluminum, which lose electrons to achieve noble gas configurations. It also covers transition elements like titanium, chromium, and nickel, which follow specific electron loss patterns. The script then shifts to anions, detailing how elements like chlorine, nitrogen, and oxygen gain electrons to form isoelectronic ions with full outer shells. The video concludes with the isoelectronic nature of phosphide, sulfide, and chloride ions.

Takeaways

• 🔬 Positive ions, or cations, are formed when atoms lose electrons, starting from the highest energy sublevel.
• 🧲 Sodium loses its 3s electron to form a sodium ion with the electron configuration of neon.
• 🌟 Magnesium loses two 3s electrons to form a 2+ ion, achieving the electron configuration of neon.
• 🛠 Aluminium loses one 3p and two 3s electrons to form a 3+ ion, also achieving neon's electron configuration.
• 🔄 Ions of sodium, magnesium, and aluminium are isoelectronic, meaning they have the same electron configuration as neon.
• 🌐 Transition elements, like titanium, lose their 4s electrons first when forming 2+ ions, followed by 3d electrons.
• 🚫 Chromium is an exception to the Aufbau principle, losing electrons differently when forming a 3+ ion.
• 💧 Negative ions, or anions, are formed when atoms gain electrons, achieving a full outer shell.
• ❄️ Chlorine gains one electron to form a chloride ion with a full outer shell, similar to the electron configuration of argon.
• 🌱 Nitrogen gains three electrons to form a nitrate ion, achieving the electron configuration of oxygen.
• 🍃 Oxygen gains two electrons to form an oxide ion, similar to the electron configuration of sulfur.
• 🌺 Fluorine gains one electron to form a fluoride ion, achieving the same electron configuration as the oxide and nitrite ions, making them isoelectronic.

Q & A

What is the electron configuration of a neutral sodium atom?

The electron configuration of a neutral sodium atom is 1s² 2s² 2p⁶ 3s¹.

How does a sodium atom form a cation?

A sodium atom forms a cation by losing its one electron in the 3s sublevel, resulting in the electron configuration of 1s² 2s² 2p⁶.

What is the electron configuration of a sodium ion?

The electron configuration of a sodium ion is 1s² 2s² 2p⁶, which is the same as that of a noble gas.

Why are electrons lost from the highest energy sublevel first?

Electrons are lost from the highest energy sublevel first because these electrons are at a higher energy state and are less tightly bound to the nucleus.

What is the electron configuration of a magnesium atom and how does it form a cation?

A magnesium atom has the electron configuration 1s² 2s² 2p⁶ 3s². It forms a cation by losing two electrons from the 3s sublevel, resulting in the electron configuration 1s² 2s² 2p⁶.

What is the electron configuration of an aluminium atom and how does it form a 3+ ion?

An aluminium atom has the electron configuration 1s² 2s² 2p⁶ 3s² 3p². It forms a 3+ ion by losing one electron from the 3p sublevel and two electrons from the 3s sublevel, resulting in the electron configuration 1s² 2s² 2p⁶.

Why are sodium, magnesium, and aluminium ions isoelectronic?

Sodium, magnesium, and aluminium ions are isoelectronic because they all achieve the same electron configuration as a noble gas, neon, when they form ions.

How does the electron configuration of titanium differ when it forms a 2+ ion?

When titanium forms a 2+ ion, it loses two electrons from the 4s sublevel, resulting in the electron configuration Ar 3d².

Why is chromium an exception to the Aufbau principle?

Chromium is an exception to the Aufbau principle because its electron configuration is Ar 4s¹ 3d⁵, and when it forms a 3+ ion, it loses one electron from the 4s sublevel and two from the 3d sublevel, resulting in the electron configuration Ar 3d³.

What is the electron configuration of a neutral chlorine atom and how does it form an anion?

A neutral chlorine atom has the electron configuration 1s² 2s² 2p⁶ 3s² 3p⁵. It forms an anion by gaining one electron, which is added to the 3p sublevel, resulting in a full outer shell of electrons.

What is the electron configuration of the nitrate ion and how is it formed?

The nitrate ion has the electron configuration Ar 2s² 2p⁶ and is formed by a nitrogen atom gaining three electrons to achieve a full 2p sublevel.

Why are the oxide, nitrite, and fluoride ions isoelectronic?

The oxide, nitrite, and fluoride ions are isoelectronic because they all have the same electron configuration, which is a full 2p sublevel, resulting in a total of eight valence electrons.

How do phosphorus, sulfur, and chlorine form their respective anions and achieve isoelectronic configurations?

Phosphorus gains three electrons to form the phosphide ion with a 3- charge, sulfur gains two electrons to form the sulfide ion with a 2- charge, and chlorine gains one electron to form the chloride ion with a 1- charge. All three achieve the same electron configuration as the noble gas argon, making them isoelectronic.