How Ions Form: Cations, Anions, and Ionic Compounds Explained
You have been hearing since childhood that there are ions in our body, where some are positive and some negative. Positively charged ions are called cations, while a negative ion is known as an anion.
An ion is an atom or a molecule that carries some charge either by losing or gaining an electron.
If we name the ions which are positively charged, then we have the following list:
K+
Na+
Ca2+
Mg2+
Negative ions are Cl-, O2-, S2-, Br-, etc.
This page will help you understand what is an ion with its types and the ion formation.
What Do You Mean by Ions?
Do you know what does ion mean and what type of ion forms when an atom loses electrons or what happens when an atom gains an electron?
An ion is a particle that possesses an electrical charge. It becomes a cation on losing an electron and becomes an anion when it gains an electron. Also, the negative charge or an electron an atom holds is always equal and opposite to the positive charge or protons of an atom.
What is a Charged Atom Called?
A charged atom is called an ion and what are ionic compounds made of; let’s understand this in detail:
What is an Ionic Compound?
From the above text, we understood what an ion is in Chemistry. Now, we will understand what is an ionic compound.
In Chemistry, we call ionic compounds chemical compounds that are formed of two or more ions held together by an electrostatic force of attraction; these electrostatic forces form bonds called ionic bonds. Here, these ionic bonds are formed between positively charged ions called cations and negatively charged ions called anions.
So, what is a cation?
What is a Cation?
Now, Let’s Understand what is a Cation with a Real-Life Example:
What do you find common among the battery, your heart, and fertile soil? The answer to this question is, it requires cations to work.
However, let’s think more specifically. Have you ever gulped down a protein shake after becoming dehydrated from vigorous physical activity? Maybe a trainer, your coach, gym teacher, or even a sports drink commercial might have told you that consuming the beverage would help you replace your electrolytes. An electrolyte is a solution that contains ions and in drinking the sports drink, you consume cations. But what is a cation?
A cation is a positively charged ion that gets attracted towards the cathode in electrolysis. As you know that an atom is electrically neutral. This is because the number of protons equals the number of electrons in an atom and the charges balance out. When an atom loses one or more electrons, it now has more protons, or positively charged particles, than electrons, or negatively charged particles.
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What Type of Ion Forms When An Atom Loses Electrons?
For example, when atoms like Na, Ca, Mg, K loses electrons, it becomes positively charged by losing electrons accordingly:
In the above, we can see that atoms on losing electron (s) become positively charged; however, the number of protons before and after the ion formation remains the same.
What is an Anion?
An anion carries a negative charge that gets attracted towards the anode in electrolysis. All non-metals gain two or more electrons and do not lose any proton. Therefore, these elements possess a net negative charge. Some examples of anions are Iodide ion (I- ), chlorine (Cl- ), hydroxide (OH-).
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Point To Ponder:
A trick to remember to distinguish between a cation and an anion is to say to yourself the following:
Cation - 'I positively love cats!', and
Anion - ‘I get annoyed with negative people.’
What Type of Ion Forms When an Atom Gains Electrons?
In the above table, we can see that non-metals like Cl, F, O, N when gains electron (s) becomes negatively charged or an anion with the increase in the number of electrons; however, the number of protons before and after the ion formation remains the same.
FAQs on What Is an Ion in Chemistry?
1. What is an ion in chemistry?
In chemistry, an ion is an atom or a molecule that has a net electrical charge due to the loss or gain of one or more electrons. A standard atom is electrically neutral because it has an equal number of protons (positive charge) and electrons (negative charge). When this balance is disrupted through an electron transfer, the resulting charged particle is called an ion.
2. How is an ion formed from a neutral atom?
An ion is formed through a process called ionisation, where a neutral atom either loses or gains electrons.
- If an atom loses one or more electrons, it has more protons than electrons, resulting in a net positive charge. This type of ion is called a cation.
- If an atom gains one or more electrons, it has more electrons than protons, resulting in a net negative charge. This type of ion is called an anion.
3. What is the fundamental difference between an atom and an ion?
The fundamental difference between an atom and an ion lies in their electrical charge and, consequently, their number of electrons.
- An atom is always electrically neutral, meaning it has an equal number of protons and electrons.
- An ion is an electrically charged particle, meaning it has an unequal number of protons and electrons because it has either lost or gained electrons.
4. What are the two main types of ions? Please provide examples.
The two primary types of ions are cations and anions, distinguished by their charge:
- Cations: These are positively charged ions formed when an atom loses one or more electrons. For example, a sodium atom (Na) loses one electron to become a sodium cation (Na⁺). Metals typically form cations.
- Anions: These are negatively charged ions formed when an atom gains one or more electrons. For example, a chlorine atom (Cl) gains one electron to become a chloride anion (Cl⁻). Non-metals typically form anions.
5. Why do atoms lose or gain electrons to form ions?
Atoms form ions primarily to achieve a more stable electron configuration, often resembling that of the noble gases. This drive for stability is explained by the octet rule, which states that atoms tend to have eight electrons in their outermost shell (valence shell). Atoms will lose, gain, or share electrons to satisfy this rule. For instance, a sodium atom with one valence electron will readily lose it to achieve a stable, full outer shell, becoming a Na⁺ ion.
6. How are ions represented using chemical symbols and formulas?
Ions are represented by writing the chemical symbol of the atom or molecule, followed by a superscript that indicates the net charge. The number of the charge is written before the sign (+ or -). If the charge is single (1+ or 1-), the number '1' is omitted. For example:
- A calcium atom that has lost two electrons is written as the cation Ca²⁺.
- An oxygen atom that has gained two electrons is written as the anion O²⁻.
- A potassium atom that has lost one electron is written as the cation K⁺.
7. What is the difference between monatomic and polyatomic ions?
The key difference is in their composition. A monatomic ion is formed from a single atom that has lost or gained electrons, such as the sodium ion (Na⁺) or the sulfide ion (S²⁻). In contrast, a polyatomic ion is composed of two or more atoms covalently bonded together that act as a single, charged unit. Examples include the sulfate ion (SO₄²⁻) and the ammonium ion (NH₄⁺).
8. How does forming an ion change a substance's properties, for example, in the case of table salt?
Forming an ion drastically alters a substance's properties. A classic example is sodium chloride (NaCl), or table salt.
- Sodium (Na) in its atomic form is a highly reactive metal that explodes in water.
- Chlorine (Cl) in its elemental form is a toxic, poisonous gas.
9. What happens when ionic compounds like salt dissolve in water?
When an ionic compound dissolves in water, it undergoes dissociation. This means the compound breaks apart into its individual, freely moving ions. The polar water molecules surround the ions, with the positive ends of water molecules attracting the anions and the negative ends attracting the cations. This separation of charges is why solutions of ionic compounds can conduct electricity, whereas pure water and the solid ionic compound cannot.
