Chemical bonding (chem)

Question 1

What is ionic bonding?

Answer 1

Strong electrostatic forces of attraction between oppositely-charged ions.

Question 2

What is the structure of ionic compounds?

Answer 2

Lattice → regular three-dimensional arrangement of atoms, molecules, or ions.

Question 3

How are ions arranged in the lattice of ionic compounds?

Answer 3

Ions in the lattice are closely packed and arranged in an orderly manner.

Question 4

What holds ions in fixed positions within the lattice?

Answer 4

Strong electrostatic forces of attraction between oppositely charged ions.

Question 5

explain why this misconception is wrong: ionic bonding is the transfer of electrons between atoms

Answer 5

transfer of electrons is the process by which ions are formed from atoms. ionic bonding occurs after ions are formed and refers to the electrostatic attraction between the ions

Question 6

explain why this misconception is wrong: metals and non-metals always form ionic bonds

Answer 6

general trend but does not apply universally (e.g. aluminnum chloride)

Question 7

define lattice

Answer 7

regular three-dimensional arrangement of atoms, molecules, or ions

Question 8

what are all the physical properties of ionic compounds

Answer 8

• high melting point
• solid cnn conduct electricity, aqueous/molten state can
• generally soluble in water but insoluble in organic solvents

Question 9

explain why ionic compounds have high melting points

Answer 9

• ____ has a giant ionic structure
• large amt of energy is required to overcome the strong electrostatic forces of attraction between oppositely-charged ions

Question 10

Suggest why magnesium oxide has a much higher melting point than sodium chloride although both substances have giant ionic structures

Answer 10

The charges of magnesium ions and oxide ions are Mg2+ and O2- respectively while the charged of sodium ions and chloride ions are Na+ and Cl-
Due to the greater charges, more energy is required to overcome the stronger electrostatic forces of attraction between magnesium ions and oxide ions compared to those between sodium ions and chloride ions

Question 11

explain why tonic compounds can only conduct electricity in molten or aqueous state

Answer 11

• Ionic compounds have a giant ionic structure
• Solid state: oppositely-charged ion are held in fixed positions by strong electrostatic forces of attraction
• Thus, ions not free-moving and hence the compound cnn conduct electricity
• molten or aqueous stae: strong electrostatic forces of attraction between oppositely-charged ions are overcome
• ions become free-moving, enabling compound to conduct electricity

Question 12

what do the shared electrons in covalent bonding use to hold the atoms together

Answer 12

electrostatic attraction between negatively charged electrons and positively charged nuclei of bonded atoms

Question 13

what is electronegativity

Answer 13

ability of an atom to attract a shared paired of electrons towards itself in a covalent bond

Question 14

what are the trends in electronegativity

Answer 14

across a period: increases
down a group: decreases

Question 15

what do simple molecular substances consist of

Answer 15

many small, discrete molecules

Question 16

what are the properties of simple molecular structures

Answer 16

• low melting and boiling point
• do not conduct electricity in any state
• generally insoluble in water but soluble in organic solvents

Question 17

why do simple molecular structures have low melting/boiling points

Answer 17

• ____ has a simple molecular structure
• a small amt of energy is required to overcome the weak intermolecular forces of attraction between methane molecules

Question 18

why do simple molecular substances generally not conduct electricity in any state

Answer 18

• ____ has a simple molecular structure
• there are no free-moving valence electrons or ions available to conduct electricity

Question 19

what is a giant covalent structure

Answer 19

atoms that formed a network of covalent bonds that extend throughout a structure

Question 20

what do ionic compounds consist of

Answer 20

continuously repeating 3D lattice with an uncountably large number of formula units of positive and negative ions

Question 21

define allotrope

Answer 21

different forms of the same element in the same physical state with atoms arranged differently

Question 22

what is the structure of a diamond

Answer 22

• giant covalent structure
• in a structure of a diamond, each carbon atom is covalently bonded to four other carbon atoms in a tetrahedral arrangement

Question 23

does a diamond have a high or low melting point and explain why

Answer 23

• very high melting point
• large amount of energy is required to break strong covalent bonds between barbon atoms

Question 24

does diamond conduct electricity and explain why

Answer 24

• does not conduct electricity in any state
• has a giant covalent structure
• all the four valence electrons of each carbon atom are used for covalent bonding, ao there are no free-moving valence electrons present to conduct electricity

Question 25

what is the solubility of diamond

Answer 25

insoluble in water and organic solvents

Question 26

what the hardness of a diamond and explain why

Answer 26

- very hard - all carbon atoms are hekd by strong covalent bonds throughout the structure - due to hardness, diamond often used to coat drill bits and cutting tools

Question 27

explain the structure of graphite

Answer 27

- has a goant covalent layered structure - made up of many rings of hexagonal rings of carbon atoms - each carbon atom forms strong covalent bonds with three other carbon atoms in hexagonal arrangement in layers - carbon atoms are held together by strong covalent bonds but the layers are held together by weak intermolecular forces of attraction

Question 28

does a graphite have a high or low melting point and explain why

Answer 28

- very high melting point - giant covalent layered structure - large amount of energy required to break the strong covalent bonds between the carbon atoms

Question 29

does graphite conduct electricity and explain why

Answer 29

- conducts electricity - each carbon atom uses only three out of four valence electrons in bonding - the valence electrons not used in bonding are free-moving to conduct electricity

Question 30

what is the solubility of graphite

Answer 30

insoluble in water and organic solvents

Question 31

what is the hardness of graphite and explain why also give one application of graphite

Answer 31

- soft and slippery - graphite has a giant covalent layered structure - the layers of carbon atoms in graphite are held tgt by weak intermolecualr forces of attraction. - layers are able to slide over one another when a force is applied - used as a solid lubricant to reduce friction in machinery

Question 32

what are metallic bonds

Answer 32

strong electrostatic forces of attraction between positive metal ions and 'sea' of free-moving electrons

Question 33

what are the properties of metallic bonds

Answer 33

- high melting point - good conductors of electricity - insoluble in water and organic solvents - ductile and malleable

Question 34

do metals have a high or low meting point and why

Answer 34

- high melting point - ___ has a giant metallic structure - Large amt of energy is needed to overcome the strong electrostatic forces of attraction between positive metal ions and 'sea' of free-moving valence electrons

Question 35

are metals a good or poor conductor of electricity and explain why

Answer 35

- good conductor - _____ has a giant metallic structure - 'sea' of free-moving valence electrons present to conduct electricity

Question 36

are metals ductile and malleable and why

Answer 36

- yes - metals have a giant metallic structure - when force applied, orderly layers of metal ions can slide over one another easily without breaking metallic bond

Question 37

how is ionic bonding formed

Answer 37

electrons transfer from metallic atoms to non-metallic atoms to form positively charged ions and negatively charged ions respectively

Question 38

how is covalent bonding formed

Answer 38

electrons shared between non-metallic atoms to form molecules

Question 39

how is metallic bonding formed

Answer 39

metal atoms lose their valence electrons, forming positively charged ions valence electrons become delocalised and free-moving, forming a lattoce of positive ions surrounded by a 'sea' of free-moving electrons

Question 40

what are polymers

Answer 40

consist of long-chain molecules formed when many small molecules called monomers join tgt

Question 41

what are the properties of macromolecules

Answer 41

- solids at room temp - not able to conduct electricity in any state

Question 42

what is the melting point of macromolecules and explain why

Answer 42

- solids at room temp - large molecular size - vz simple molecular substances, more energy needed to overcome the stronger intermolecular forces of attraction - consists of a mixture of molecules with various chain lengths --> does not have a fixed melting point - typically softens over a range of tem

Question 43

are macromolecules able to conduct electricity and why

Answer 43

- not able to conduct electricity in any state - do not have mobile ions or electrons