chemical bonding

Question 1

atom

Answer 1

-smallest particle of an element that has the chemical properties of that element

Question 2

molecule

Answer 2

-two or more atoms covalently bonded together

Question 3

element

Answer 3

-pure substance that cannot be split into two or more simpler substances by physical or chemical processes

Question 4

compound

Answer 4

-substance which contains two or more elements chemically combined in a fixed composition
-physical and chemical properties of a compound are different from its constituent elements

Question 5

mixture

Answer 5

-two or more substances physically mixed in any proportion
-the chemical properties of a mixture are the same as those of its components

Question 6

definition of ionic bonds

Answer 6

-strong electrostatic forces of attraction between oppositely charged ions

Question 7

structure of ionic compounds

Answer 7

-ionic compounds exist in a giant ionic lattice structure

Question 8

ionic compounds have high melting and boiling point, and are hard

Answer 8

-it has giant ionic structure
-large amount of energy needed to overcome strong electrostatic forces of attraction between the oppositely-charged ions

Question 9

ionic compounds are unable to conduct electricity in solid state

Answer 9

-it has giant ionic structure
-in solid state, the oppositely charged ions can only vibrate about their fixed positions due to the strong electrostatic forces of attraction. hence, there are no free-moving ions to conduct electricity

Question 10

ionic compounds are able to conduct electricity in molten and aqueous state

Answer 10

-in the aqueous/ molten state, the electrostatic forces of attraction between oppositely charged ions are weakened. hence, there are free-moving ions to conduct electricity.

Question 11

solubility of ionic compounds

Answer 11

-most ionic compounds are soluble in water
-usually insoluble in organic solvents

Question 12

definition of covalent bonds

Answer 12

-strong electrostatic forces of attraction between the positively-charged nuclei and shared pair of electrons

Question 13

simple covalent molecules have low melting and boiling point

Answer 13

-it has simple covalent structure
-only small amount of energy needed to overcome the weak intermolecular forces

Question 14

simple covalent molecules are generally unable to conduct electricity in any state

Answer 14

-it has simple covalent structure
-there are no free-moving ions or electrons to conduct electricity

Question 15

solubility of simple covalent molecules

Answer 15

-most simple covalent substances are insoluble in water
-ammonia, hydrogen chloride and sulfur dioxide are exceptions
-usually soluble in organic solvents

Question 16

giant covalent molecules have very high melting and boiling point

Answer 16

-it has a giant covalent structure
-large amount of energy needed to overcome strong covalent bonds between carbon atoms

Question 17

diamond is unable to conduct electricity

Answer 17

-it has a giant covalent structure
-each carbon atom uses up all four of its valence electrons to form covalent bonds with four other carbon atoms
-it does not have any delocalised electrons to conduct electricity

Question 18

graphite is able to conduct electricity

Answer 18

-it has a giant covalent structure
-each carbon atoms uses 3 out of its 4 valence electrons to form covalent bonds with 3 other atoms
-each carbon atom has one valence electron not used in bonding. it is delocalised and is able to conduct electricity.

Question 19

diamond is very hard

Answer 19

-it has giant covalent structure
-large amount of energy needed to overcome strong covalent bonds between carbon atoms
-used as cutting tool or drill bit to cut hard objects like glass and rocks

Question 20

graphite is soft and slippery

Answer 20

-it has a giant covalent structure
-soft and slippery because the layers of carbon atoms are held by weak intermolecular forces and can slide over each other easily
-used as a lubricant and in pencil lead

Question 21

solubility of giant covalent molecule

Answer 21

-insoluble in water

Question 22

definition of metallic bonding

Answer 22

-strong electrostatic forces of attraction between metallic cations and ‘sea’ of delocalised electrons

Question 23

structure of metals

Answer 23

-giant metallic structure
-each metal atom contributes its valence electrons to a ‘sea’ of delocalised electrons which are free-moving and can move throughout the metal

Question 24

metals have high melting and boiling point (group 1 metals are exceptions)

Answer 24

-it has a giant metallic structure
-large amount of energy needed to overcome the strong electrostatic forces of attraction between the metallic cations and ‘sea’ of delocalised electrons

Question 25

metals are able to conduct electricity

Answer 25

-it has giant metallic structure
-the sea of delocalised electrons are free-moving and therefore metals can conduct electricity

Question 26

pure metals are malleable and ductile

Answer 26

-pure metals consist of layers of atoms of the same size
-when a force is applied, these layers of atoms can slide over each other easily

Question 27

solubility of metals

Answer 27

-insoluble in water