chem bonding and structure (eya)

Question 1

what is electronegativity

Answer 1

a measure of an atom’s ability to attract the electrons in a covalent bond to itself

Question 2

how does electronegativity affect bonding

Answer 2

high electronegativity difference forms ionic bonds (metals have low electronegativity)
low electronegativity difference forms covalent bonds (non-metals have high electronegativity)

Question 3

more electronegative atom acquires a partial _______

less electronegative atom acquires a partial _____

Answer 3

negative charge; positive charge

Question 4

how do dipole moments work

Answer 4

show the movement of an electron cloud toward the more electronegative atom (because it attracts the electrons toward itself)

Question 5

how to identify a polar compound

Answer 5

• electronegativity difference ≥0.5
• dipole moment arrows do not cancel each other out

Question 6

why dont noble gases have electronegativity

Answer 6

they are inert and have no tendency to gain or share electrons

Question 7

definition of ionic bonding

Answer 7

the strong electrostatic forces of attraction between oppositely charged ions

Question 8

definition of covalent bonding

Answer 8

strong electrostatic forces of attraction between a shared pair of electrons and the nuclei of both atoms

Question 9

definition of metallic bonding

Answer 9

strong electrostatic forces of attraction between positively charged ions and the ‘sea’ of delocalised electrons

Question 10

why do metals have free electrons

Answer 10

due to close packing of metal atoms, they ‘lose’ their valence electrons to become positively charged ions. electrons no longer belong to a particular metal atom and are said to be delocalised

Question 11

what is an alloy

Answer 11

a mixture of a metal with one or more other elements

Question 12

types of bonding structures

Answer 12

ionic bonding: giant ionic lattice structure
covalent bonding: simple molecular structure; giant covalent structure; macromolecular structure
metallic bonding: giant metallic lattice structure

Question 13

physical properties

Answer 13

hardness, solubility, electrical conductivity, melting and boiling point

Question 14

hardness of giant ionic lattice structures

Answer 14

hard: strong electrostatic forces of attraction between oppositely charged ions causes ions to resist motion and be resistant to deforming

brittle: when a strong enough force is applied, ions are displaced from their lattice positions. when ions of the same charge from adjacent layers face each other, strong repulsive forces between them causes lattice structure to cleave evenly

Question 15

hardness of simple molecular structures

Answer 15

soft: only a small amount of force is required to overcome weak intermolecular forces of attraction

Question 16

hardness of giant covalent structures

Answer 16

diamond, silicon dioxide — hard: large amount of force is needed to break the numerous covalent bonds between atoms present throughout the entire structure

graphite — soft: layers of carbon atoms are held loosely by intermolecular forces of attraction, little force is needed to overcome them

Question 17

hardness of giant metallic lattice structures

Answer 17

malleable and ductile: when sufficient force is applied, layers of ions can slide over one another easily without disrupting metallic bonding

Question 18

definition of malleability and ductility

Answer 18

ability of a metal to be hammered into thin sheets; ability of a metal to be drawn into a thin wire

Question 19

hardness of alloys

Answer 19

not malleable and ductile: different sizes of atoms present disrupt the regular lattice arrangement, hence layers of atoms cannot slide over one another easily

Question 20

types of solvents

Answer 20

aqueous solvents; organic solvents

Question 21

aqueous solvents vs organic solvents

Answer 21

aqueous solvents: water-based, used to dissolve polar substances
organic solvents: carbon-based, used to dissolve non-polar substances

Question 22

solubility of giant ionic lattice structures

Answer 22

soluble in aqueous solvents, insoluble in organic solvents

Question 23

solubility of simple molecular structures

Answer 23

insoluble in aqueous solvents (EXCEPT iodine, sugar, hcl, ammonia etc), soluble in organic solvents

Question 24

solubility of giant molecular structures

Answer 24

insoluble in both aqueous and organic solvents

Question 25

solubility of macromolecular structures

Answer 25

insoluble in aqueous solvents MAY be soluble in organic solvents

Question 26

solubility of giant metallic lattice structures

Answer 26

insoluble in aqueous and organic solvents

Question 27

electrical conductivity of giant ionic lattice structures

Answer 27

conduct electricity in aqueous state: ionic compounds dissolve in water and dissociate to form mobile ions that can conduct electricity conduct electricity in molten state: large amount of energy can overcome strong electrostatic forces of attraction between oppositely charged ions, making them mobile

Question 28

electrical conductivity of simple molecular structures

Answer 28

do not conduct electricity: no mobile charge carriers to conduct electricity

Question 29

electrical conductivity of giant covalent structures

Answer 29

normal — do not conduct electricity: no mobile charge carriers to conduct electricity graphite — can conduct electricity: 1 unbonded valence electron per carbon atom that is mobile within the layer to conduct electricity

Question 30

electrical conductivity of macromolecular structures

Answer 30

do not conduct electricity: no mobile charge carriers to conduct electricity

Question 31

electrical conductivity of giant metallic lattice structures

Answer 31

conduct electricity in solid and molten states: mobile electrons present to conduct electricity

Question 32

electrical conductivity of alloys

Answer 32

conduct electricity: presence of sea of delocalised electrons to act as mobile charge carriers

Question 33

melting and boiling points of giant ionic lattice structures

Answer 33

high melting and boiling points: large amount of energy required to overcome the strong electrostatic forces of attraction between oppositely charged ions

Question 34

melting and boiling points of simple molecular structure

Answer 34

low melting and boiling point: small amount of energy required to overcome weak intermolecular forces of attraction between molecules

Question 35

melting and boiling points of giant molecular structures

Answer 35

high melting and boiling points: large amount of energy required to overcome the strong covalent bonds between atoms present throughout the structure

Question 36

melting and boiling points of macromolecules

Answer 36

low melting and boiling points: small amount of energy required to overcome weak intermolecular forces of attraction between molecules

Question 37

melting and boiling points of giant metallic lattice structures

Answer 37

high melting and boiling points: large amount of energy required to overcome strong electrostatic forces of attraction between positive ions and ‘sea’ of delocalised electrons

Question 38

melting and boiling points of alloys

Answer 38

high but not as high as ionic compounds: presence of other elements act as impurities that lower the melting and boiling points compared to a pure metal different sizes of atoms in an alloy disrupt the regular arrangement of atoms, making bonds between them weaker which lowers melting and boiling points.