How To Find How Many Electrons An Element Has

Element atoms have a natural capability to bond with other chemical element atoms. A molecule is formed when 2 or more atoms of the same or different elements unite to form a stable structure. A molecule of sodium chloride is formed when an atom of sodium and a molecule of chlorine unite, while a molecule of hydrogen fluoride is formed when an atom of hydrogen and a molecule of fluorine combine. Each atom has some capability for mixing with other atoms. Valency refers to an chemical element'south power to combine its constituent atoms. Hydrogen and chlorine are believed to accept the same valency. The valency of other elements is determined past comparing them to hydrogen or chlorine.

Atoms are made up of electrons, protons and neutrons. By and large, protons and neutrons lie at the center of an cantlet called the nucleus and electrons circumduct effectually the nucleus in a fixed path called orbits or shells.

The shells are named 'M', 'Fifty', '1000', 'N' and then on. The innermost shell is the 'K' shell which contains upwardly to 2 electrons, followed by the 'L' shell which contains up to 8 electrons followed by the 'M' shell which contains up to 18 electrons and and then the 'Due north' crush which contains upwardly to 32 electrons. The different types of atoms come together and form elements.

structure of atom

Structure of Atom

What is Valence electrons?

The electrons in the outermost shell around an atomic nucleus are known as valence electrons. Valence electrons are important considering they provide detailed information on an chemical element's chemical characteristics, such every bit whether it is electronegative or electropositive in nature, or the bond lodge of a chemical compound, which indicates the number of bonds that may be formed between two atoms.

Thus, valence electrons are defined as,

The number of electrons present in the outermost shell of an element that takes part in chemical bonding is chosen valence electrons.

For example, Lithium (Li) has atomic number equal to iii. Its electronic configuration is Thousand = ii and L = one, this implies, G subshell is fully filled while L subshell i.due east. the outermost vanquish has only one electron, which is its valence electron as shown in the below diagram:

valence electrons

Valence Electron in a Lithium atom

Changes in the atomic structure are bars to the electrons in the outermost shell, i.due east. valence electrons, regardless of the blazon of chemical interaction between atoms, whether information technology an ionic, covalent, or metal bond.

A valence electron is an electron that is attached to an cantlet and may exist used to establish a chemic interaction; in a single covalent bond, both atoms contribute one valence electron to form a shared pair. The number of valence electrons tin can bear upon the chemical characteristics of an element also as its power to collaborate with other elements:

A valence electron in a main group element can only be in the outermost electron shell.
Chemically, an atom with a closed shell of valence electrons is inert. Because the additional valence electrons are quickly removed to create a positive ion, an atom with i or two valence electrons more than a closed shell is extremely reactive.
Because of a trend to either obtain the missing valence electrons (creating a negative ion) or share valence electrons, an atom with one or two valence electrons fewer than a closed shell is also extremely reactive (thereby forming a covalent bail).
A valence electron, similar an electron in an inner shell, may receive or release free energy in the course of a photon. Atomic excitation occurs when an electron gains plenty energy to migrate (jump) to an outer vanquish.
Ionization occurs when an electron breaks abroad from its associated atom'southward valence shell, resulting in the formation of a positive ion. When an electron loses energy (and so emits a photon), it might migrate to an inner shell that isn't completely occupied.

Determination of Valence Electrons in an Atom

Although the number of shells rises as we travel down a grouping, the number of valence electrons remains constant.

While the number of valence electrons increases by 1 over time, the number of shells remains abiding. The number of shells around an element'southward nucleus is indicated by the period number (row number).

What is Valency?

The valency of an cantlet is equal to the number of valence electrons that this atom can gain or lose during chemical reactions. Or in other words:

The corporeality of hydrogen atoms, chlorine atoms, or double the number of oxygen atoms that one atom of an element may combine with is referred to as its valency.

The valency of an element refers to the number of valence electrons in that element that participate in chemical processes. A chemic chemical compound is created when ii or more components are combined in a certain mass proportion. A stable chemical compound is formed when one cantlet of i element unites with a specific number of atoms of another element. All components have dissimilar capabilities for mixing.

Valency of Metals

A metal is an chemical element with i, two, or three electrons in its valence shell (except hydrogen and helium, which are not-metals). In chemic processes, metals tend to shed their valence electrons and complete their octet. Therefore,

Valency of metal element = Number of electrons in its valence beat

Elements from Group 1, 2 & 13 of the periodic table have valencies 1, 2, iii respectively which is similar to the electron configuration in their last shell.

For Example:

Sodium (Na)

The Electronic configuration of Na is 11 (K = ii; L = 8; Grand = one). They have 1 electron in their outermost crush. Then, the valency of Sodium is i as shown below:

valence electrons of sodium

Valency of Sodium

Magnesium (Mg)

The Electronic configuration of Mg is 12 (One thousand = two; 50 = 8; Thousand = ii). They have 2 electrons in their outermost beat. So, the valency of Magnesium is 2 as testify beneath:

valence electrons of magnesium

Valency of Magnesium

Aluminium (Al)

The Electronic configuration of Al is 13 (K = 2; L = viii; M= 3). They have 3 electrons in their outermost shell. So, the valency of Aluminium is iii every bit shown below:

valence electrons of aluminium

Valency of Aluminium

Valency of Non-Metals

If an chemical element's valence shell has 5 or 6 or 7 or 8 electrons, it is classified as a non-metal. To complete its octet, a not-metal requires iii or ii or one or 0 electrons. Every bit a result, a non-metallic chemical element's valency = viii – number of electrons in its outermost trounce.

Elements from Groups 15, sixteen & 17 of the periodic table have five, 6, 7 electrons respectively in their last shell so the valency of non-metals is decided past finding the number of electrons required to complete its octet configuration.

For case:

Nitrogen (N)

The Electronic configuration of N is seven (K = ii; Fifty = v; M= 0). They accept 5 electrons in their outermost trounce. And then, the valency of Nitrogen is: 8 – five = 3 every bit shown below:

valence electrons of nitrogen

Valency of Nitrogen

Oxygen (O)

The Electronic configuration of O is eight (K = 2; L = 6; M= 0), They accept half dozen electrons in their outermost vanquish. So, the valency of Oxygen is : 8 – 6 = 2 as shown below:

valence electrons of oxygen

Valency of Oxygen

Fluorine (F)

The Electronic configuration of F is 9 (K = 2; L = 7; M= 0). They take 7 electrons in their outermost shell. So, the valency of Fluorine is: 8 – 7 = i equally shown below:

valence electrons of fluorine

Valency of Fluorine

Valency of Nobel gases

Group 18 elements of the periodic table are called noble gases because they do not react at all equally they take the most stable electronic configuration due to having the maximum number of valence electrons in its outer shell. The valency is zero as every noble gas's outermost shell is filled hence they exercise not lose or gain any electron.

For Example:

Neon (Ne)

The electronic configuration of Ne is x (K = 2; L = 8; M= 0). They have 8 electrons in their outermost shell. And then, the valency of Neon is : eight – 8 = 0.

valence electrons of neon

Valency of Neon

Relation Betwixt Valency and Valence Electrons

Valency explains the bond germination of atoms. Whereas, valence electrons are related to elemental characters. Valency is merely a concept or idea and doesn't involve manual of electrons. Whereas, valence electron involves transmission of electrons in the germination of bonds. Both valency and valence electrons are practical for whatsoever element.

Since, only the valence electrons (outermost electrons) participate in chemical bonding, an element'southward valency is determined past the number of valence electrons (outermost electrons) in its cantlet. The corporeality of valence electrons in an element's cantlet or the number of electrons necessary to consummate eight electrons in the valence crush determines the element's valency. Sodium, for case, contains one valence electron and thus a valency of 1. As a result, the valency of sodium is equal to the amount of valence electrons in its atom. A metal element's valency is equal to the number of valence electrons in its atom in general.

Valency of a metal = Number of valence electrons in its atom

A valence electron, like an electron in an inner shell, may receive or release energy in the grade of a photon. Atomic excitation occurs when an electron gains enough energy to drift (jump) to an outer shell. Ionization occurs when an electron breaks away from its associated atom'due south valence trounce, resulting in the formation of a positive ion. When an electron loses energy (and and so emits a photon), information technology might migrate to an inner shell that isn't completely occupied.

Valency of a non-metal = eight – Number of valence electrons in its atom

The valency of hydrogen is the one exception to this rule. Hydrogen's valency is equal to the number of valence electrons, which is one (though hydrogen is a not-metal element).

valence electrons hydrogen

Valency of Hydrogen

Sample Questions

Question 1: Name the electrons of an atom that are involved in bond formation?

Reply:

Only valence electrons of an atom are involved in bail formation.

Question 2: What is the electron distribution of the Chlorine atom? How many electrons are at that place in the last shell?

Answer:

Since, the atomic number of a Chlorine atom (Cl) is 17.

Therefore, the electronic distribution of Cl: K = 2, Fifty = 8, M = 7

And the last vanquish has 7 electrons.

Question 3: What is the electronic configuration of a positively charged sodium ion (Na⁺)?

Reply:

Nosotros know that, Atomic number of Na is 11

Since, Diminutive number = Number of protons = eleven

Also, in a neutral atom the number of protons = number of electrons = 11

So, Number of electrons in (Na⁺) ion = 11 – 1 = 10

Thus, the electronic configuration of (Na⁺) ion is Thou = 2, L = eight.

Question 4: An element 'Eastward' contains seven electrons in the 'M' shell as valence electrons. What is the atomic number of 'E'? And as well cheque whether 'E' is a metal or non-metal.

Reply:

As 'East' has 7 electrons in the 'M' shell as valence electrons, the electronic configuration of 'E' is K = 2, L = 8, M = 7.

This implies, the diminutive number is 17.

Besides, we know that elements of groups 15, 16, 17 along with Hydrogen is non – metal.

Then, 'East' is a non – metal.

Question v: The atomic number of lithium is iii. Its mass number is vii. How many protons and neutrons are nowadays in a lithium cantlet?

Answer:

Nosotros know that,

Number of neutrons = Mass number – Atomic number

Then, Number of neutrons = 7 – three = 4

And, Number of protons = Atomic number

Hence, Number of protons = 3.

Question half-dozen: Why Helium, Neon and Argon take zero valency?

Answer:

The mentioned elements belong to the group 18 of the periodic table. According to that, the outermost shell of Helium, Neon and Argon is completely filled . They do not take any tendency to combine with other elements. Hence, they have zero valency.

Question seven: An electron is present in the outermost beat out of the cantlet of an element X. What would be the nature and value of charge on the ion formed if this electron is removed from the outermost shell?

Reply:

Just 1 electron is present in the instance of metals of group 1. According to that, element 'X' has only one electron in information technology'southward outermost beat i.e, valence electron. It will donate this electron inorder to course ion and achieve the octet state. The accuse volition be +one.