properties of ionic compound and covalent substances

Question 1

structure of ionic compounds

Answer 1

giant ionic crystal lattice structure consisting of alternating positive and negative ions held by strong electrostatic forces of attraction

Question 2

properties of ionic compounds

Answer 2

1. high mp and bp
2. soluble in water and insoluble in organic solvents
3. conduct electricity in molten/aqueous state only
4. hard but brittle

Question 3

structure of covalent substances

Answer 3

exist as simple covalent molecules with weak intermolecular forces of attraction

Question 4

properties of covalent substances

Answer 4

1. low mp and bp
2. insoluble in water and soluble in organic solvents
3. do not conduct electricity

Question 5

why are ionic compounds soluble in water and not organic solvents

Answer 5

there are water molecules present in water which attracts ions and pulls it away from its structure. it then dissolves and form an aqueous solution.
In organic : there is no water present, so no water molecules to attract ions away from its lattice structure, hence ions stay in place in its lattice structure

Question 6

why does ionic compound have high mp and bp

Answer 6

structure + very large amount of energy is required to overcome the strong electrostatic forces of attraction between oppositely charged ions

Question 7

why does ionic compound conduct electricity only in molten

Answer 7

in molten state, there are mobile ions to act as charge carriers to conduct electricity

in other states, there are no mobile ions to act as charge carriers and held in its lattice structure

Question 8

why are ionic compounds hard and brittle

Answer 8

hard : structure + makes it resistant to deforming

brittle : when enough force is applied, ions move away from its lattice structure and repulsive force is stronger than attractive forces and causes the lattice structure to shatter

Question 9

why do covalent substances have low bp and mp

Answer 9

structure + little energy required to overcome the weak intermolecular forces of attraction between molcules

Question 10

why do covalent substances not conduct electricity at any state

Answer 10

there are no mobile ions in covalent substances to carry charges to conduct electricity

Question 11

what are alloys

Answer 11

alloy is a mixture of a metal and one or two other element

Question 12

what causes the difference in properties between alloys and metals

Answer 12

irregular lattice arrangement

Question 13

physical properties of metal

Answer 13

malleable and ductile

metals are arranged in a regular lattice arrangement but when enough force is applied, layers of atoms can slide past each other

Question 14

physical properties of alloys

Answer 14

harder and stronger than metals

alloys are made up of different sizes of atoms and has an irregular lattice arrangement which is disrupted. so a larger force is needed to make the layers slide over each other

Question 15

similarities of alloys and metals

Answer 15

high mp and bp

can conduct electricity
mobile valence electrons are present and can act as charge carriers to conduct electricity.