Bonding, structure and properties of matter

Question 1

Ionic bonding

Answer 1

• When a metal and a non metal react together, the metal atom loses electrons to form a positively charged ion.
• When a non metal gains these electrons they form a negatively charged ion. These oppositely charged ions are strongly attracted to one another by electrostatic forces.

Question 2

Sodium chloride (ionic bonding)

Answer 2

• The sodium atom gives up its outer electron, becoming a Na+ ion. The chlorine atom picks up the electron, becoming a Cl- ion.

Question 3

Giant covalent structures

Answer 3

Definition:
- Macromolecules where all atoms are bonded to each other by strong covalent bonds.
Properties:
- High melting, boiling points due to strong covalent bonds.
- Do not conduct electricity(no charged particles) except in some cases like graphite.

Question 4

Examples of giant covalent structures

Answer 4

Diamond:
- Each carbon atom forms four covalent bonds in a very rigid structure.
- Very hard and has a high melting point.
Graphite:
- Each carbon atom forms three covalent bonds, creating layers of hexagons.
- Has one delocalised electron per atom, allowing it to conduct electricity.
Silicon Dioxide:
- Also known as silica, forms giant structures of silicon and oxygen.
- Commonly found in sand.

Question 5

Melting and boiling points- Giant covalent substances

Answer 5

• Require breaking strong covalent bonds to melt or boil, resulting in high/boiling points.

Question 6

Melting and boiling points- Simple molecular substances

Answer 6

• Require breaking weak intermolecular forces, leading to lower melting/boiling points.

Question 7

Comparison of Melting points- Diamond vs poly(ethene)

Answer 7

• Diamond: Has a higher melting point than poly(ethene) due to its strong covalent bonds compared to the weaker intermolecular forces in poly(ethene).

Question 8

What is one use of fullerenes in medicine?

Answer 8

• Drug delivery systems, where they encapsulate drugs to target specific cells.

Question 9

How do fullerenes function as catalysts?

Answer 9

Their large surface area allows them to enhance the efficiency of chemical reactions by providing more area for catalyst molecules to attach.

Question 10

Why are fullerenes effective as lubricants?

Answer 10

Their spherical shape allows them to slide past each other easily, reducing friction and wear in mechanical applications.

Question 11

Definition of metallic bonding

Answer 11

• Metallic bonding involves delocalised electrons that move freely between positive metal ions, creating a strong electrostatic attraction that holds the structure together.

Question 12

Structure of Metals

Answer 12

• Metals consists of giant structure with delocalised electrons in the outer shell of metal atoms.

Question 13

Properties of metals

Answer 13

• Most metals are solid at room temperature due to strong electrostatic forces requiring energy high energy to break.

Question 14

Conductivity

Answer 14

• Metals are good conductors of electricity and heat because delocalised electrons carry electrical charge and thermal energy through the structure.

Question 15

Malleability

Answer 15

• Metals are malleable, allowing layers of atoms to slide over each other, making them easy to bend, hammer, or roll into sheets.

Question 16

Alloys vs Pure metals

Answer 16

• Pure metals are often too soft for certain applications, so they are mixed with other metals to create alloys, which are generally harder and more useful.

Question 17

Effect of Alloying

Answer 17

• The introduction of different-sized atoms in alloys distorts the layers of atoms, making it more difficult for them to slide over each other, which increases hardness.