CHAP 4 CHEMICAL BONDING

Question 1

describe the formation of ions ( non-metals & metals )

Answer 1

non-metals usually gain electrons to form negative ions (anions) while metals usually lose electrons to form positive ions ( cations ) to attain stable electronic configuration or noble gas configuration

Question 2

describe the formation of ionic bonds between metals and non-metals

Answer 2

1) Ionic bonds take place between oppositely charged ions -> usually present in compound of metal & non-metal
2) formed by electron transfer where metal atoms donates electrons to non-metal atom
3) ions are arranged in an ionic lattice and are held together by electrostatic forces of attraction

Question 3

explain why ionic bonds are hard but brittle

Answer 3

1) when force is applied, repulsive forces between the ions of the same charge becomes larger than the attractive forces
2) lattice structure shatters -> brittle

Question 4

what is the structural properties of IONIC COMPOUND

Answer 4

1) have a giant ionic lattice structure
2) consist of alternating positive and negative ions
3) held together by electrostatic forces of attraction

Question 5

describe the physical properties of a ionic compound MVPSES

Answer 5

1) high melting point due to the strong electrostatic FOA between the ions of opposite charges, hence large amount of energy is needed to overcome/ break these forces -> hence, ionic compounds have high boiling & melting point.
* ionic compounds usually solid/ crystalline in room temperature
2) not volatile ( does not evaporate easily )
3) Do not conduct electricity in solid state but only in aqueous/ molten state due to the presence of mobile ions
4) usually soluble in water ; insoluble in organic solvents

Question 6

describe the formation of covalent bonding

Answer 6

formed between non-metal atoms and by sharing electrons between atoms and usually have electronic configuration of a noble gas
* can be found as simple molecules or large molecules
* only outermost electrons used for electron sharing
* can be also formed between atoms of the same elements

Question 7

describe the structural properties of simple covalent molecules

Answer 7

1) covalent molecules are held together by strong covalent bonds but weak intermolecular forces of attraction
2) only a small amount of energy is needed to overcome these weak intermolecular forces of attraction hence covalent bonds are usually gases or liquids at r.t.p

Question 8

describe the physical properties of covalent bonds MVPSES

Answer 8

1) usually liquids/ gases at r.t.p due to the weak intermolecular FOA, hence less energy is needed to overcome the forces
2) low boiling & melting points due to weak intermolecular FOA ( however covalent bonds are strong and are not broken during melting or boiling )
3) volatile (evaporate easily)
4) do not conduct electricity
5) usually insoluble in water; soluble in organic solvents