Covalent Bonding_Key Questions

Question 1

What are Molecules?

Answer 1

• discrete groups of atoms of known formula bonded together

Question 2

What are the 2 types of bonds in molecular compounds?

Answer 2

1. Intramolecular bonds 2. intermolecular bonds

Question 3

What are intramolecular bonds?

Answer 3

bonds within the molecules

Question 4

What are intermolecular bonds?

Answer 4

bonds between the molecules

Question 5

Why do non-metals not conduct Electricity?

Answer 5

Non-metals do not conduct electricity because they do not contain free-moving charged particles (neither delocalised electrons nor ions).

Question 6

Why do non-metals have low melting and boiing points?

Answer 6

Non-metals have low melting and boiling temperatures because they have weak intermolecular bonds between molecules.

Question 7

How is a Covalent Bond Formed?

Answer 7

When non-metallic atoms share electrons

Question 8

What is a single Covalent Bond?

Answer 8

• share two electrons, one from each atom
• eg: Hydrogen and Chlorine

Question 9

What is a double Covalent Bond?

Answer 9

• share two pairs of electrons (four in total), two from each atom
• eg: Oxygen 2,6

Question 10

What is a Triple Covalent Bond?

Answer 10

• share three pairs of electrons (Eight in total), two from each atom
• eg: Nitrogen 2,5

Question 11

What do Electron Dot Diagrams show?

Answer 11

• Simplifies the drawing of molecules
• Show the valence shell electrons of an atom
• Can distinguish between bonding and non-bonding electrons

Question 12

What do Valence Structures show?

Answer 12

• Simplifies the drawing of molecules
• lines are used to represent the two electrons in a covalent bond. One line =’s one pair of electrons

Question 13

What are other types of diagrams that show the shape of a Molecule?

Answer 13

• Other types include a Ball and Stick Model and a Space Filling Model
• Ball and Stick – Atoms are represented as Spheres connected by Rods.
• Space Filling – Whole Atoms are represented as spheres. Different colours are used to identify different elements

Question 14

What are the limitations of the Different Models?

Answer 14

1. Electron Dot – Does not show the relative size of atoms or shape of the molecule
2. Valence – Does not show the relative size of atoms or shape of the molecule
3. Ball-and-Stick – Shows the shape not the relative sizes of the atoms
4. Space-Filling – Shows the relative size and position of the atoms but does not show bond angles or types of bonds

Question 15

Draw electron dot and valence structures for the following molecules - fluorine (F2)

Answer 15

Question 16

Draw electron dot and valence structures for the following molecules - hydrogen fluoride (HF)

Answer 16

Question 17

Draw electron dot and valence structures for the following molecules - water (H2O)

Answer 17

Question 18

Draw electron dot and valence structures for the following molecules - tetrachloromethane (CCl4)

Answer 18

Question 19

Draw electron dot and valence structures for the following molecules - phosphine (PH3)

Answer 19

Question 20

Draw electron dot and valence structures for the following molecules - butane (C4H10)

Answer 20

Question 21

Draw electron dot and valence structures for the following molecules - carbon dioxide (CO2)

Answer 21