topic 2: bonding and structure

Question 1

define ionic bonding

Answer 1

the strong electrostatic attractionbetween oppositely charged ions

Question 2

explain how ionic radius effects ionic bonds

Answer 2

smaller radius = stronger bond. electrostatic attraction decreses with distance

Question 3

explain the increase in ionic radius down group 1

Answer 3

same charged ion but increasing number of shells

Question 4

explain the decrease in ionic radius across a period with isoelectronic ions

Answer 4

same structure of electrons but more protons further to the right

Question 5

why do ionic solids only dissolve in polar solvents

Answer 5

because the ions are charged they can be separated if the new bonds formed with the solvent are stronger

Question 6

why cant ionic solids be shaped

Answer 6

when the layers slide over one another, like charged repel and the solid breaks apart

Question 7

define covalent bonding

Answer 7

the strong electrostatic attraction between two positive nuclei and the shared pairs of electrons in the bond

Question 8

what effects bond length and bond enthalpy in a covalent bond

Answer 8

the higher the electron density between the atoms, the greater the attraction. greater attraction reduces bond length and increase bond enthalpy. (more electrons in bond)

Question 9

define electronegativity

Answer 9

the ability of an atom to attract the bonding electrons in a covalent bond

Question 10

how does electronegativity change across the periodic table

Answer 10

increases across period

decreases down the group

Question 11

what increases electronegativity. 2

Answer 11

higher nuclear charge

smaller atomic radii

Question 12

why can covalent bonds be polar

Answer 12

uneven electronegativities so charge of shared electrons are ditributed towards one of the atoms causing partial charges in the mollecule

Question 13

describe london forces

Answer 13

electrons move randomly around atoms and cause instantaneous dipoles. this dipoles interact with other attoms causign a week force of attraction

Question 14

what effects the strength of london forces

Answer 14

larger electron clouds = stronger forces

greater surface area = stronger forces

Question 15

how do the shapes of organic mollecules effect the strengh of london forces

Answer 15

longer chains = more contact = stronger

more branches = cant pack closely together = weaker

Question 16

describe permenant dipole permenant dipole interactions

Answer 16

weak electrostatic forces of attraction between 𝛿+ and 𝛿- of different polar mollecules.

Question 17

explain how hydrogen bonding works

Answer 17

due to the electronegativity of oxygen, nitrogen and fluorine, they draw the bonding electrons away from the hydrogen atom. the hydrogen has such a high charge density that its form weak bonds with lone pairs on the other atom (NOF)

Question 18

why does ice float on water

Answer 18

ice is less dense because lattice structure has a lot of empty space

Question 19

why are alcohols less volitile than similar alkanes

Answer 19

the polar hydroxyl group allows hydrogen bonding between adjacent oxygens and hydrogens

Question 20

when do solvents work

Answer 20

when the bonds that form between the solvent and the substance are the same or stonger the substance will dissolve