Bonding - HQ

Question 1

Metallic bonding

Answer 1

• The electrostatic attraction between a sea of delocalised valence electrons and metal cations
• Creates metallic substances

Question 2

Ionic bonding

Answer 2

• The electrostatic attraction between anions and cations
• Usually between a metal and a nonmetal (not always)
• I.e., a transfer of electrons

Question 3

Covalent bonding

Answer 3

• The sharing of electrons
• Creates covalent molecular OR covalent network substances

Question 4

Coordinate/dative covalent bond

Answer 4

A type of covalent bond in which both electrons which make up the bond are provided by the same atom.

Question 5

List

Metal (metallic substances) properties

Answer 5

• High electrical conductivity in solid and liquid states
• Malleable and ductile
• Shiny/reflective (high lustre)
• High melting and boiling points
• Hard materials
• Alloys are stronger

Question 6

Why are metals good conductors?

Answer 6

Due to charged mobile particles

Question 7

Why are metals malleable and ductile?

Answer 7

When metals are bent/stretched, layers of positive ions are forced to move relative to each other, but no matter where they go, electrons are free to move into the space between (positive) ions, keeping the structure together by ensuring electrostatic attractions (metallic bonds) are maximised.

If smn leaves, they find smn else to attract to

Question 8

Why are metals shiny/reflective? (high lustre)

Answer 8

The interaction between photons of light from an external light source and mobile electron sea on the surface of the metal lattice creates metallic reflection/shininess

If u throw smt at a moving object, bounces off

Question 9

Why do metals have high melting/boiling points?

Answer 9

Metallic, ionic, and covalent network substances exist as lattices. Lattices require a large amount of energy to overcome intermolecular bonding.

Question 10

Why are alloys stronger?

Answer 10

They incorporate impurity atoms which disrupt the orderly nature of the lattice, making it more difficult for layers of positive ions to slide over each other if the metal is bent, therefore stronger and harder than pure metal.

Question 11

Ionic substance properties

Answer 11

• Don’t conduct in a solid state
• Can conduct in molten (melted) state or in solution (aqueous)
• Hard and brittle
• High melting and boiling points

Question 12

Why are ionic substances non-conductors when solid?

Answer 12

Ions are not free to move within the rigid lattice.

Question 13

Why are ionic substances conductors when molten/aqueous?

Answer 13

When melted/dissolved, ions dissociate (bonds break), causing them to be charged and mobile.

Question 14

Why are ionic substances hard and brittle?

Answer 14

• If force is applied, ions of like charges move next to each other, causing them to repel, making the object shatter

+ves next to each other, -ves next to each other. uh oh.

Question 15

Why do ionic substances have high melting and boiling points?

Answer 15

They exist as lattices. Lattices require a large amount of energy to overcome intermolecular bonding.

Question 16

Covalent molecular substances properties

Answer 16

• Exist as discrete molecules (therefore easy to break apart)
• Low melting and boiling points (therefore exist usually as liquid/gas at room temperature
• Non-conductors in liquid or solid states
• Often soft

Question 17

Why do covalent molecular substances have low melting and boiling points? (and therefore exist as liquid/gas at room temperature)

Answer 17

Only a small amount of energy is required to overcome/disrupt the weak intermolecular forces between discrete molecules.

Question 18

Why are covalent molecular substances non-conductors in liquid or solid states?

Answer 18

Molecules are neutral and electrons and protons are localised within each molecule, therefore no free/mobile charged particles to carry/conduct electricity.

(hv mobility, no charge????)

Question 19

Why are covalent molecular substances soft?

Answer 19

Bonds between molecules (intermolecular) are weak, meaning little force is required to push molecules past each other in a solid state.