9.3.5 Coordinate Covalent Bond

Q1. Write some characteristics of metals.

1. Metals usually show metallic luster.
2. They have high melting and boiling points.
3. They are good conductors of heat and electricity.
4. They are usually hard and heavy.
5. They can be shaped into wires or sheets when pressure is applied.

Q2. Why is it relatively easy to remove electrons from metallic atoms?

Metals have low values of ionization energy. Which means their nuclei do not hold the outermost electrons tightly, making it easier to remove them.

Q3. Why is it relatively easy to convert a metallic atom into a cation?

Because of their low ionization energy, metal atoms do not strongly hold their outer electrons. This makes it easier to remove electrons and form positively charged ions (cations).

Q4. What do you mean by the “sea of electrons” in metals?

In metals, the outermost electrons leave their atoms and move freely in the empty spaces between the metal atoms. These free electrons are not attached to any specific nucleus, forming a “sea of electrons.”

Q5. What are mobile electrons in metals?

Mobile electrons are the outermost electrons in metal atoms that move freely in the spaces between atoms. Since they are not bound to any specific nucleus and can move throughout the metal.

Q6. What is a metallic bond?

A metallic bond is a type of chemical bond in which positively charged metal ions are held together by a sea of mobile electrons.

Q7. On what factors does the strength of a metallic bond depend?

The strength of a metallic bond depends on:

1. The positive charge on metallic ion
2. Number of mobile electrons released by each metal atom

Q8. Why is the metallic bond in magnesium metal stronger than that in sodium metal?

The strength of a metallic bond depends on the charge of the metallic cation and the number of electrons released by the metal atoms. Magnesium metal releases two electrons and forms a +2 cation, whereas sodium releases only one electron and forms a +1 cation. Therefore, magnesium has stronger metallic bonding than sodium.

Q9. Why is the metallic bond in magnesium stronger than that in sodium?

Magnesium atoms release two electrons and form +2 cations, while sodium atoms release only one electron to form +1 cations. More electrons and a higher positive charge make the metallic bond in magnesium stronger than in sodium.

Q10. Why is the melting point of magnesium higher than that of sodium?

Since magnesium forms stronger metallic bonds due to its +2 charge and release of two electrons, it requires more energy to break these bonds. This results in a higher melting point compared to sodium.

Q11. What makes metals good conductors of heat and electricity?

The presence of free moving (mobile) electrons allows metals to conduct heat and electricity

Q12. Why are metals hard and heavy?

Metals are hard and dense because their atoms are packed in tightly held layers. These closely stacked layers make metals strong and give them weight. Under pressure, these layers slip past each other without breaking.

Q13. Why are metals bendable (malleable and ductile)?

Metals consist of layers of atoms that can slide over one another when pressure is applied. This allows metals to be drawn into wires (ductility) or hammered into sheets (malleability).

Q14. What type of atoms form metallic bonds?

Only metal atoms form metallic bonds. They have low ionization energies and easily lose their outermost electrons to create a sea of free electrons.

Q15. Give a comparison of a metallic bond with an ionic bond.

Both metallic and ionic bonds involve the loss of one or more electrons. In an ionic bond, these electrons are accepted by non-metals, forming a bond between cations and anions. However, in metallic bonding, the electrons become mobile and move freely throughout the metal.

Q16. What are some uses of metals?

Metals are used in various fields such as industries, machinery, automobiles, railways, aircraft, rockets, construction, electronics, jewelry, and electric wiring.