Ionic compounds Archives

What are the Two Types of Ions and how are they Different

Ion:
An ion is a positively or negatively charged atom (or group of atoms). An ion is formed by the loss or gain of electrons by an atom, so it contains an unequal number of electrons and protons.
Example: Sodium ion Na⁺, magnesium ion Mg²⁺, chloride ion Cl^–, and oxide ion O^2–.
There are two types of ions :

cations

anions.

1. Cation
A positively charged ion is known as cation. A cation is formed by the loss of one or more electrons by an atom.
Example: Sodium atom loses 1 electron to form a sodium ion, Na⁺, which is cation :
What are the Two Types of Ions and how are they Different 1

What are the Two Types of Ions and how are they Different 1

The ions of all the metal elements are cations.
2. Anion
A negatively charged ion is known as anion. An anion is formed by the gain of one or more electrons by an atom.
Example: A chlorine atom gains 1 electron to form a chloride ion, Cl^–, which is an anion.
What are the Two Types of Ions and how are they Different 3

An anion contains more electrons than a normal atom. A normal atom (or a neutral atom) contains an equal number of protons and electrons. Now, since an anion is formed by the addition of one or more electrons to an atom, therefore, an anion contains more electrons than protons. The ions of all the non metal elements are anions.
Simple ions
Those ions which are formed from single atoms are called simple ions.
Example: Sodium ion, Na⁺, is a simple ion because it is formed from a single sodium atom, Na.
Compound ions
Those ions which are formed from groups of joined atoms are called compound ions
Example: Ammonium ion NH₄⁺, is a compound ion which is made up of two types of atoms joined together, nitrogen and hydrogen.

Ionic compounds
The compounds which are made up of ions are known as ionic compounds. In an ionic compound, the positively charged ions (cations) and negatively charged ions (anions) are held together by the strong electrostatic forces of attraction. The forces which hold the ions together in an ionic compound are known as ionic bonds or electrovalent bonds. Since an ionic compound consists of an equal number of positive ions and negative ions, so the overall charge on an ionic compound is zero.
Example: Sodium chloride (NaCl) is an ionic compound which is made up of equal number of positively charged sodium ions (Na⁺) and negatively charged chloride ions (Cl^–).
Some ionic compound

S.No.

Name

Formula

Ions present

Sodium chloride

NaCl

Na⁺ and Cl^–

Potassium chloride

KCl

K⁺ and Cl^–

Ammonium chloride

NH₄Cl

NH₄⁺ and Cl^–

Magnesium chloride

MgCl₂

Mg²⁺ and Cl^–

Calcium chloride

CaCl₂

Ca²⁺ and Cl^–

Magnesium oxide

MgO

Mg²⁺ and O^2–

Calcium oxide

CaO

Ca²⁺ and O^2–

Aluminium oxide

Al₂O₃

Al³⁺ and O^2–

Sodium hydroxide

NaOH

Na⁺ and OH^–

Copper sulphate

CuSO₄

Cu²⁺ and SO₄^2–

Calcium nitrate

Ca(NO₃)₂

Ca²⁺ and NO₃^–

How do you write the formula for ionic compounds?

Method to deduce the formulae of ionic compounds:

Metals from Groups 1, 2 and 13 combine with non-metals from Groups 15, 16 and 17 to form ionic compounds.

Table shows how the metal atoms of Groups 1, 2 and 13 form positive ions with different charges.

Group	Number of valence electrons	Number of electrons donated to achieve a stable noble gas electron arrangement	Charge of positive ion	Example of ions
1	1	1	+ 1	Li⁺, Na⁺, K⁺
2	2	2	+2	Mg²⁺, Ca²⁺, Ba²⁺
3	3	3	+3	Al³⁺

Table shows how the non-metal atoms of Groups 15, 16 and 17 form negative ions with different charges.

Group	Number of valence electrons	Number of electrons accepted to achieve a stable noble gas electron arrangement	Charge of negative ion	Example of ions
15	5	3	-3	N^3-
16	6	2	-2	O^2-, S^2-
17	7	1	-1	F^–, Cl^–, Br^–, I^–

Table shows the formulae of ionic compounds obtained when a metal from Group 1, 2 or 13 combines with a non-metal from Group 15, 16 or 17.

Elements that combined		Formula of ionic compound	Example
Metal atom R from	Non-metal atom T from	Formula of ionic compound	Example
Group 1	Group 17	RT	Potassium chloride, KCl
Group 1	.Group 16	R₂T	Sodium oxide, Na₂O
Group 1	Group 15	R₃T	Lithium nitride, Li₃N
Group 2	Group 17	RT₂	Calcium fluoride, CaF₂
Group 2	Group 16	RT	Magnesium sulphide, MgS
Group 2	Group 15	R₃T₂	Calcium nitride, Ca₃N₂
Group 13	Group 17	RT₃	Aluminium chloride, AICI₃
Group 13	Group 16	R₂T₃	Aluminium oxide, Al₂O₃
Group 13	Group 15	RT	Aluminium nitride, AlN

The information in above Tables can be used to determine the formulae of ionic compounds as shown in the following examples.

People also ask

Writing formulas for ionic compounds examples

1. An atom of element D has 20 electrons. An atom of element E has 18 neutrons and a nucleon number of 35. Deduce the formula of the compound formed between elements D and E.
Solution:
How do you write the formula for ionic compounds 1
1 atom of element D combines with 2 atoms of element E to form a compound.
∴ Formula of the compound = DE₂

2. Element X has a proton number of 13. An ion of element Y has 16 protons and 18 electrons. Deduce the formula of the compound formed between elements X and Y.
Solution:
Electron arrangement of atom X = 2.8.3
Element X has 3 valence electrons.
During bond formation, atom X loses 3 electrons to form a X³⁺ ion in order to achieve a stable octet electron arrangement.
Charge of a Y ion = Charge of 18 electrons + Charge of 16 protons
= (-18) + (+16)
= -2
How do you write the formula for ionic compounds 2
2 atoms of element X combine with 3 atoms of element Y to form a compound.
∴ Formula of the compound = X₂Y₃

3. The following table shows the number of neutrons and the nucleon numbers of atoms of elements Q and R. Q and R are not the actual symbols of the elements.
How do you write the formula for ionic compounds 3
Element Q reacts with element R to form a compound. What is the molar mass of the compound formed?
Solution: