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What is a Coordinate Bond (chemistry)?
Grade Level:
Class 8
Space Technology, EVs, Climate Change, Biotechnology, HealthTech, Robotics, Chemistry, Physics
Definition
What is it?
A coordinate bond, also called a dative bond, is a special type of covalent bond where both the shared electrons come from only one of the two atoms. It's like one friend bringing both samosas to share, instead of each bringing one.
Simple Example
Quick Example
Imagine you and your friend are sharing a mobile phone for a project. In a regular covalent bond, you both put in money to buy it. But in a coordinate bond, only one of you buys the phone, and then you both use it together for the project. The phone (electrons) comes from just one person (atom).
Worked Example
Step-by-Step
Let's look at the formation of the ammonium ion (NH4+):
1. First, a Nitrogen atom (N) has 5 valence electrons and needs 3 more to complete its octet.
---2. Three Hydrogen atoms (H) each have 1 valence electron. They form three regular covalent bonds with Nitrogen, sharing one electron each.
---3. Now, Nitrogen has 8 electrons (5 of its own + 3 shared from H) and each Hydrogen has 2 electrons. So, a stable Ammonia molecule (NH3) is formed. Nitrogen still has one lone pair (two unshared electrons).
---4. A Hydrogen ion (H+) is a Hydrogen atom that has lost its only electron, so it has an empty orbital and needs 2 electrons to be stable.
---5. The Nitrogen atom in NH3 'donates' its lone pair of electrons to the H+ ion. Both electrons for this new bond come from Nitrogen.
---6. This forms a coordinate bond between N and H+.
---7. The resulting molecule is the Ammonium ion (NH4+), which has a positive charge because the H+ was positively charged.
Why It Matters
Coordinate bonds are crucial in understanding how many important chemicals, like the ones used in medicines (HealthTech) or catalysts in industrial processes, are formed. Chemists and material scientists use this knowledge to design new materials and develop life-saving drugs.
Common Mistakes
MISTAKE: Thinking that in a coordinate bond, one atom gives away electrons completely. | CORRECTION: In a coordinate bond, electrons are shared, just like in a covalent bond. The difference is that both shared electrons come from a single atom, not one from each.
MISTAKE: Confusing a coordinate bond with an ionic bond. | CORRECTION: An ionic bond involves the complete transfer of electrons, creating ions. A coordinate bond is a type of covalent bond where electrons are shared, even if they originate from one atom.
MISTAKE: Believing that only one specific type of atom can form coordinate bonds. | CORRECTION: Many atoms with lone pairs of electrons (like Nitrogen, Oxygen, Sulfur) and atoms with empty orbitals (like Boron, or positive ions like H+) can participate in forming coordinate bonds.
Practice Questions
Try It Yourself
QUESTION: Which atom 'donates' the electron pair in a coordinate bond – the one with a lone pair or the one needing electrons? | ANSWER: The atom with a lone pair of electrons 'donates' the electron pair.
QUESTION: If a water molecule (H2O) reacts with a hydrogen ion (H+) to form a hydronium ion (H3O+), what type of bond is formed between oxygen and the new hydrogen? | ANSWER: A coordinate bond is formed, as the oxygen atom in H2O donates a lone pair of electrons to the H+ ion.
QUESTION: Explain why a coordinate bond is considered a special type of covalent bond, not an ionic bond, even though electrons come from one atom. | ANSWER: It's a special type of covalent bond because the electrons are still shared between the two atoms, forming a strong bond. It's not ionic because there is no complete transfer of electrons to form separate positive and negative ions.
MCQ
Quick Quiz
In a coordinate bond, where do the shared electrons come from?
One electron from each atom
Both electrons from one atom
Both electrons are transferred completely to one atom
Electrons are not shared at all
The Correct Answer Is:
B
In a coordinate bond, both electrons that form the shared pair come from only one of the two atoms involved in the bond. Options A describes a regular covalent bond, and C describes an ionic bond.
Real World Connection
In the Real World
Coordinate bonds are very important in 'complex ions' found in many biological systems. For example, the iron in your blood (haemoglobin) forms coordinate bonds with oxygen, allowing your body to transport oxygen from your lungs to all your cells. This process is vital for life and is studied in Biotechnology and HealthTech to develop new treatments.
Key Vocabulary
Key Terms
LONE PAIR: A pair of valence electrons that are not shared with another atom in a covalent bond. | COVALENT BOND: A chemical bond formed by the sharing of electron pairs between atoms. | VALENCE ELECTRONS: The outermost electrons of an atom that participate in chemical bonding. | OCTET RULE: The tendency of atoms to prefer to have eight electrons in their outermost shell.
What's Next
What to Learn Next
Now that you understand coordinate bonds, you can explore other types of chemical bonds like metallic bonds, which are crucial for understanding how metals conduct electricity. This will help you build a complete picture of how atoms join together to form everything around us!
