Bonding

Question 1

ionic bond

Answer 1

positive and negative ions are attracted to each other to form an ionic lattice

Question 2

mpt/bpt of ionic compounds

Answer 2

• high mpt/bpt
• many strong electrostatic attractions to be broken

Question 3

conductivity of ionic compounds

Answer 3

• conductors only when molten or in solution
• ions carry out the charge when they are free to move

Question 4

hardness of ionic compounds

Answer 4

• hard
• brittle
• ions are held rigidly in the lattice
• stress brings ions of the same charge closr to proximity and structure breaks

Question 5

solubility of ionic compounds

Answer 5

• mostly soluble
• charged ions are carried off by polar water molecules unless electrostatic attraction is too large

Question 6

structure of ionic compounds

Answer 6

• giant lattice of repeating ions in 3D
• electrostatic attraction between oppositely charged ions causes -ve to surround the +ve

Question 7

covalent bond

Answer 7

• where two atoms each donate 1 electron to form a pair held between the two atoms
• non-metal + metal

Question 8

mpt/bpt of covalent compounds

Answer 8

• low mpt/bpt

Question 9

polarity of covalent compounds

Answer 9

• Δ of electronegativity between the two bonded atoms causes the bon to be polar
• electron pair will be closer to the more electronegative atom

Question 10

what does the polarity of a molecule depend on?

Answer 10

(1) no polar bonds = non-polar
(2) polar bonds non-symmetric = polar
(3) polar bonds symmetric = non-polar

Question 11

solubility of non-polar molecules

Answer 11

• generally soluble in non-polar solvents

Question 12

solubility of polar molecules

Answer 12

• generally soluble in polar solvents

Question 13

relationship between forces of attraction in liquids + forces of attraction in solid

Answer 13

• if the force of attraction of the liquid particles for the solid particles is greater than the force of attractions felt by the solid particles for eachother, the solid dissolves

Question 14

coordinate bond

Answer 14

• a coordinate bond is a covalent bond (a shared pair of electrons) in which btoh electrons come from the same electron

Question 15

examples of coordinate bonds

Answer 15

H3O+, NH4+, CO, Al2Cl6

Question 16

metallic bonding

Answer 16

• metal atoms ‘lose’ their outer electrons and become delocalised
• atoms are free to move throughout the entire metal
• delocalised electrons hold the cations strongly

Question 17

conductivity of metallic compounds

Answer 17

• electrons can flow, high electrical conductivity

Question 18

why are metallic compounds ductile (stretched into wires) and malleable (formed into shapes)?

Answer 18

• distorting the atoms does not cause repulsion

Question 19

mpt/bpt of metallic compounds

Answer 19

• high mpt/bpt

Question 20

thermal conducticiy of metallic compounds

Answer 20

• free moving electrons allow for high thermal conductivity

Question 21

common alloys

Answer 21

• bronze (copper + tin)
• brass (copper + zinc)
• steel (iron +carbon)