Chemical bonding

Question 1

Intramolecular bond

Answer 1

Bond which occurs between atoms within the molecules

Question 2

Covalent bond

Answer 2

Sharing of at least one pair or electrons by two non-metal atoms

Question 3

Electronegativity

Answer 3

The measure of the tendency of an atom to attract a bonding pair of electrons

Question 4

Electronegativity values

Answer 4

Decrease down a group (size of atoms and number of energy levels increases) and increase across a period (non-metals have greater tendency to attract electrons than metals)

Question 5

Difference in electronegativity

Answer 5

Difference = 0 then bonding electrons are equally shared between the two atoms involved

Difference = not zero then the bonding electrons will be closer to the atom with the higher electronegativity

Question 6

Pure (non-polar) covalent bonds

Answer 6

Equal sharing of electrons. Formed between two identical atoms or two atoms of different elements with identical electronegativity

Question 7

Polar covalent bonds

Answer 7

Unequal sharing of electrons leading to a dipole forming. Occurs within molecules in which elements have different electronegativities

Question 8

Simple molecules

Answer 8

• weak intramolecular forces
• usually gases at room temperature
• form molecular lattice in solid phase
• solids have low melting and boiling points
• do not conduct as they have no free electrons

Question 9

Diamond (giant covalent structure)

Answer 9

• each carbon atom is covalently bonded to four other carbon atoms
• stronger bonds than intramolecular forces
• high melting point and boiling point
• no delocalised electricity so doesn’t conduct elec

Question 10

Graphite

Answer 10

• each carbon is covalently bonded to three other carbon atoms
• layers can slide over each other due to weak intramolecular forces holding together
• softer than diamond
• has one delocalised electron so can conduct elec

Question 11

Silica

Answer 11

• lots of covalent bonds
• high boiling point and melting point

Question 12

Ionic bonding

Answer 12

Transfer of electrons and subsequent electrostatic attraction

Question 13

Ionic compounds properties

Answer 13

• do not form molecules but form giant ionic lattice structures
• particles have high melting and boiling points
• brittle
• can only conduct elec when ions are free to move (molten or dissolved in water)

Question 14

Metallic bonding

Answer 14

Occurs between a positive kernel and a sea of delocalised electrons

Question 15

Metallic bonding properties

Answer 15

• metals have high melting and boiling points
• good conductors of elec and heat as free electrons can carry a charge or heat energy through metal
• are malleable and ductile as free electrons allow metal atoms to slide over each other