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.

Outlines

00:00

🔬 Formation of Positive Ions (Cations)

This paragraph discusses the electron configurations of positive ions, known as cations. It begins with the example of a sodium atom, which loses its 3s electron to form a sodium ion with the electron configuration of a noble gas. The paragraph then explains that electrons are lost from the highest energy sublevel first, a principle demonstrated with further examples of magnesium and aluminum, which form ions by losing electrons from the 3s and 3p sublevels, respectively. These ions are isoelectronic, meaning they share the same electron configuration as neon. The paragraph also introduces the concept of transition elements, such as titanium, chromium, and nickel, which follow a specific pattern when forming ions, losing electrons from the 4s sublevel before the 3d sublevel, except for chromium, which is an exception to the Aufbau principle.

05:00

🌀 Formation of Negative Ions (Anions) and Isoelectronic Species

The second paragraph delves into the formation of negative ions or anions, starting with chlorine gaining an electron to form a chloride ion with a full outer shell. It then discusses nitrogen, which gains three electrons to form the nitrate ion, oxygen gaining two electrons to become the oxide ion, and fluorine gaining one electron to form the fluoride ion. These ions are highlighted as isoelectronic, sharing the same electron configuration. The paragraph extends this concept to phosphorus, sulfur, and chlorine, which form ions by gaining electrons and achieve the same electron configuration, thus being isoelectronic with each other. The summary underscores the process of ion formation through electron gain and the resulting isoelectronic relationships among different ions.

Keywords

💡Electron Configuration

Electron configuration refers to the distribution of electrons in an atom or ion. It is a fundamental concept in chemistry that helps to understand chemical properties and behavior. In the video, electron configurations are used to describe how atoms form ions by losing or gaining electrons, such as the sodium atom with the configuration 1s² 2s² 2p⁶ 3s¹ losing an electron to become a sodium ion with the configuration 1s² 2s² 2p⁶.

💡Cations

Cations are positively charged ions formed when an atom loses one or more electrons. They are central to the video's discussion on how different atoms form ions. For instance, the sodium atom becomes a cation by losing its 3s electron, resulting in the electron configuration of a noble gas.

💡Ion Formation

Ion formation is the process by which atoms become ions through the loss or gain of electrons. The video explains this process for both cations and anions, such as magnesium losing two 3s electrons to form a 2+ ion, aligning with the theme of achieving noble gas electron configurations.

💡Noble Gas Configuration

A noble gas configuration is an electron configuration that matches that of the noble gases, which are stable due to having full outer electron shells. The video emphasizes how atoms form ions to achieve this stable configuration, as seen with sodium, magnesium, and aluminum ions all having the same electron configuration as neon.

💡Aufbau Principle

The Aufbau principle is a rule in chemistry that dictates the order in which electrons fill subshells in an atom. The video notes that this principle generally applies when transition elements form ions, such as titanium losing its 4s electrons first, but highlights chromium as an exception to this rule.

💡Transition Elements

Transition elements are a group of elements in the periodic table known for their ability to form multiple cation states due to their variable oxidation states. The video uses titanium, chromium, and nickel as examples to illustrate how these elements form ions, losing electrons from the 4s sublevel before the 3d.

💡Anions

Anions are negatively charged ions formed when an atom gains one or more electrons. The video discusses the formation of anions, such as the chlorine atom gaining an electron to form a chloride ion with a full outer shell, emphasizing the concept of achieving stability through full sublevels.

💡Isoelectronic

Isoelectronic species are ions or molecules with the same number of electrons and often similar electron configurations. The video uses the terms to describe how different ions, like the oxide ion and the fluoride ion, have the same electron configuration, despite being formed from different atoms.

💡Electron Sublevels

Electron sublevels are the different energy levels within a principal energy level where electrons reside. The video explains that electrons are lost from the highest energy sublevel first during ion formation, such as sodium losing its 3s electron.

💡Full Outer Shell

A full outer shell refers to an electron configuration where the outermost energy level or sublevel is completely filled with electrons. In the video, this concept is used to describe stable ions like the chloride ion, which has a full 3p sublevel after gaining an electron.

💡Chromium Exception

The chromium exception refers to the deviation of chromium from the typical Aufbau principle, where it is more stable with a half-filled d sublevel. The video points out that chromium forms a 3+ ion by losing its 4s electron first, then two from the 3d sublevel, resulting in a configuration of AR 3d³.

Highlights

Electron configurations of ions are discussed, focusing on positive ions or cations.

Sodium atom loses its 3s electron to form a sodium ion with a noble gas electron configuration.

Positive ions are formed by the loss of electrons from the highest energy sublevel.

Magnesium atom loses two 3s electrons to form a magnesium ion with the same electron configuration as sodium.

Aluminium atom loses electrons from 3p and 3s to form an ion with the same noble gas configuration as sodium and magnesium.

Ions of aluminium, magnesium, and sodium are isoelectronic, achieving neon's electron configuration.

Transition elements like titanium lose 4s electrons first when forming 2+ ions.

Chromium is an exception to the Aufbau principle, forming a 3+ ion with a different electron configuration.

Nickel, like other transition elements, loses 4s electrons first when forming 2+ ions.

Transition elements' ion formation involves the loss of 4s electrons before 3d electrons.

Negative ions or anions are formed by electron gain, starting with chlorine gaining an electron.

Nitrogen atom gains three electrons to form a nitrate ion with a full outer shell.

Oxygen atom gains two electrons to form an oxide ion with the same electron configuration as nitrite.

Fluorine atom gains one electron to form a fluoride ion, becoming isoelectronic with oxide and nitrite ions.

Phosphorus, sulfur, and chlorine form anions with increasing negative charges, achieving isoelectronic configurations.

The concept of isoelectronic ions is introduced, sharing the same electron configuration.

Transcripts

this is M sjcam in this video I'll be

looking at the electron configurations

of ions so we'll start by looking at

positive ions which are also known as

cations on the Left we have a sodium

atom which has the electron

configuration 1s2 2s2 2p6 3s1 the sodium

atom can lose the one electron in the 3s

sublevel to form a sodium ion which we

can see on the right the electron

configuration of the ion is 1s2 2s2 2p6

so there are two important points the

first is that positive ions are formed

when atoms lose electrons and the second

is that the electrons are lost from the

highest energy sublevel first so in the

case of the sodium atom the first

electron is taken from the 3 s sublevel

because it has the highest energy so

next we look at some more examples of

positive ions so we've already looked at

sodium which loses its one electron in

the 3s sublevel to form a 1 plus ion by

doing so it gains the electron

configuration of a noble gas next is

magnesium which has the electron

configuration any 3s to the magnesium

atom can lose these two electrons in the

3 s sublevel to form a 2 plus ion and if

we look at the electron configuration we

can see it's the same as that of the

sodium ion and next is aluminium which

has the electron configuration NE 3s2

3p2 our mininum atom can lose the one

electron in the 3p sublevel and the two

electrons in the 3 s sublevel to form a

3 plus ion and once again if we look at

the electron configuration of the

aluminium ion we can see it's the same

as that for the magnesium ion and the

sodium ion these three ions are ISO

electronic which means they have the

same electron configuration so when

aluminium magnesium and sodium form ions

they achieved the electron configuration

of a noble gas which is neon

the next three examples that we look at

are the transition elements titanium

chromium and nickel so if we start with

titanium which has the electron

configuration AR 4s 2 3 D 2 note that

this electron configuration can also be

written as AR 3 D 2 4 s 2

when titanium forms a 2 plus ion it

loses the two electrons in the 4 s

sublevel first this is true of all

transition elements so the electron

configuration of the titanium 2 plus ion

is a are 3 D 2 our next example is

chromium which is an exception to the

Aufbau principle its electron

configuration is AR 4 s 1 3 D 5

when chromium forms a 3 plus ion it

first loses the 1 electron in the 4 s

sublevel followed by 2 electrons in the

3d sublevel so the electron

configuration of the chromium 3 plus ion

is AR 3 D 3 and finally we have nickel

which has the electron configuration AR

4s2 3d8 so like all transition elements

when nickel forms a 2 plus ion it loses

the 2 electrons in the 4 s sublevel

first so the electron configuration of

the nickel 2 plus ion is AR 3 d 8 so the

important point here is that when they

form ions transition elements lose their

4s electrons first then followed by the

electrons in the 3d sublevel next we

look at the formation of negative ions

or anions on the Left we have a chlorine

atom which has the electron

configuration 1s2 2s2 2p6 3s2 3p5 the

chlorine atom can gain one electron to

form a one negative ion which we can see

on the right the electron has been added

to the 3p sublevel so the chloride ion

has a full outer shell of electrons next

we look at negative ions

so we'll start with nitrogen which has

the electron configuration a chi 2s2 2p3

the nitrogen atom gains three electrons

to form the nitrate ion which has a

three negative charge the electron

configuration is a chi 2s2 2p6 the next

example is oxygen which has the electron

configuration 2s2 2p4 the oxygen atom

can gain two electrons to form the oxide

ion which has a two negative charge the

two electrons go into the two p sub

level which gives it the same electron

configuration as the nitrite ion next is

fluorine which has the electron

configuration a chi 2s2 2p5 a flew in

atom can gain one electron to form the

fluoride ion which has a one negative

charge the one electron goes into the 2p

sub level which gives it the same

electron configuration as the oxide ion

and the nitrite ion which means that

these three ions are isoelectronic the

next three examples are phosphorus

sulfur and chlorine phosphorus gains

three electrons to form the phosphide

ion which has a three negative charge

sulfur gains two electrons to form the

sulfide ion which has a two negative

charge and chlorine gains one electron

to form the chloride ion which has a one

negative charge and once again we can

see that these three ions have the same

electron configuration

therefore they are isoelectronic