[ 1 & 2 ] 3.1.3 — Bonding

Question 2

What is an ionic bond?

Answer 2

Attraction between oppositely charged ions, formed by the transfer of electrons.

Question 3

What is a covalent bond?

Answer 3

A pair of shared electrons between two atoms.

Question 4

What is a dative covalent bond?

Answer 4

A shared pair of electrons provided by one atom.

Question 5

What is a metallic bond?

Answer 5

Attraction between cations and a sea of delocalised electrons.

Question 6

How does electronegativity vary across a period?

Answer 6

It increases due to increasing nuclear charge and constant shielding.

Question 7

How does electronegativity vary down a group?

Answer 7

It decreases due to increased electron shielding.

Question 8

What is the key determinant for bond type (ionic, covalent, metallic)?

Answer 8

The difference in electronegativity between atoms.

Question 9

What type of bond forms when the electronegativity difference is >2.1?

Answer 9

Ionic bond.

Question 10

What type of bond forms when the electronegativity difference is 0.5–2.1?

Answer 10

Polar covalent bond.

Question 11

What are the three states of matter?

Answer 11

Solid, liquid, gas.

Question 12

What is a lattice?

Answer 12

An ordered, repeating 3D arrangement of particles.

Question 13

Why do solids have fixed shapes?

Answer 13

Due to strong interparticle attractions holding a rigid structure.

Question 14

Why don’t ionic solids conduct electricity?

Answer 14

Ions are fixed in place and can’t move.

Question 15

Why do ionic compounds conduct electricity when molten?

Answer 15

Ions are free to move and carry charge.

Question 16

What type of bonding exists in metals?

Answer 16

Metallic bonding.

Question 17

Why are metals good electrical conductors?

Answer 17

They have delocalised electrons that move freely.

Question 18

What is a sigma (σ) bond?

Answer 18

A direct overlap of orbitals along the internuclear axis.

Question 19

What is a pi (π) bond?

Answer 19

An overlap of orbitals above and below the internuclear axis.

Question 20

How many bonds are in a triple bond?

Answer 20

One sigma and two pi bonds.

Question 21

What are the three types of intermolecular forces?

Answer 21

Van der Waals, dipole-dipole, hydrogen bonding.

Question 22

What causes Van der Waals forces?

Answer 22

Temporary dipoles due to shifting electron clouds.

Question 23

What increases Van der Waals force strength?

Answer 23

More electrons and greater surface area.

Question 24

What is a hydrogen bond?

Answer 24

An attraction between H covalently bonded to N, O, or F and a lone pair on a nearby molecule.

Question 25

What is the VSEPR theory?

Answer 25

Valence Shell Electron Pair Repulsion theory—used to predict molecular shapes.

Question 26

What shape results from 4 bonding pairs and 0 lone pairs?

Answer 26

Tetrahedral, bond angle ~109.5°.

Question 27

What shape results from 3 bonding pairs and 1 lone pair?

Answer 27

Trigonal pyramidal, bond angle ~107°.

Question 28

What shape results from 2 bonding pairs and 2 lone pairs?

Answer 28

Bent, bond angle ~104.5°.

Question 29

What is a giant covalent structure?

Answer 29

A substance with a 3D lattice of atoms held by covalent bonds (e.g. diamond, SiO₂).

Question 30

Why is diamond so hard?

Answer 30

Each carbon forms 4 strong covalent bonds in a tetrahedral structure.

Question 31

What allows graphite to conduct electricity?

Answer 31

Delocalised electrons between layers.

Question 32

Why is graphite soft?

Answer 32

Layers can slide over each other due to weak intermolecular forces.

Question 33

What type of structure does NaCl have?

Answer 33

Ionic lattice with high coordination number (6).

Question 34

Why does MgO have a higher melting point than NaCl?

Answer 34

Mg²⁺ and O²⁻ have higher charges, leading to stronger attraction.

Question 35

Why don't molecular substances conduct electricity?

Answer 35

They lack ions or delocalised electrons.

Question 36

What determines boiling points of Period 3 elements?

Answer 36

Bonding type and molecular size.

Question 37

Which Period 3 element has the highest boiling point?

Answer 37

Silicon (Si) due to its giant covalent structure.

Question 38

What is the trend in electrical conductivity across Period 3 metals?

Answer 38

Increases from Na to Al due to more delocalised electrons.

Question 39

What explains the low density of ice?

Answer 39

Open hexagonal hydrogen-bonded structure.

Question 40

What gives DNA its helical shape?

Answer 40

Intramolecular hydrogen bonding between N-H and C=O groups.