Bonding

Question 1

Define metallic bonding

Answer 1

strong electrostatic attraction of positive metal ions surrounded by a sea of delocalised electrons
Structure: giant lattice
Bonding: strong metallic bonds

Question 2

why is the bonding in magnesium stronger than in sodium

Answer 2

mg has a greater charge of 2+
mg has twice as many electrons in the sea of delocalised electrons
mg are smaller meaning there is a greater charge density
therefore the attraction between the mg2+ ions and delocalised electrons is stronger

Question 3

Define covalent bonding

Answer 3

shared pair of electrons between two non metals
Structure: macromolecular or simple molecular
Bonding: strong covalent

Question 4

what are macromolecular structures

Answer 4

SiO2 - silicon oxide/dioxide
carbon and silicon
e.g. diamond and graphite

Question 5

diamond

Answer 5

each carbon has 4 covalent bonds
tetrahedral structure
very high melting point
very hard
non conductor as no free delocalised electrons

Question 6

graphite

Answer 6

layers with 3 covalent bonds to each carbon
each carbon has delocalised electrons
layers held together by weak intermolecular forces
soft layers slide over each other
conductor has delocalised electrons
melting point is high still has strong covalent bonds between atoms

Question 7

Define ionic bonding

Answer 7

strong electrostatic attraction between oppositely charged ions
Structure: giant lattice
Bonding : strong ionic

Question 8

coordinate bond

Answer 8

shared pair of electrons which have both been donated from the same atom

Question 9

electronegativity

Answer 9

the power of an atom to attract the pair of electrons in a covalent bond

Question 10

2 bonding pairs 0 lone pairs

Answer 10

Linear - 180°
e.g. BeCl2

Question 11

3 bonding pairs 0 lone pairs

Answer 11

Trigonal planar - 120°
e.g. BF3

Question 12

4 bonding pairs 0 lone pairs

Answer 12

Tetrahedral - 109.5°
e.g.CH4`

Question 13

5 bonding pairs 0 lone pairs

Answer 13

Trigonal bipyramidal - 120° and 90°
e.g.PCl5

Question 14

6 bonding pairs and 0 lone pairs

Answer 14

octahedral - 90°
e.g.SF6

Question 15

3 bonding pairs 1 lone pair

Answer 15

pyramidal - 107°

Question 16

2 bonding pairs 2 lone pairs

Answer 16

v-shaped - 104.5°

Question 17

4 bonding pairs 1 lone pair

Answer 17

seesaw - 119° and 89°

Question 18

3 bonding pairs 2 lone pairs

Answer 18

trigonal planar - 120°

Question 19

2 bonding pairs 3 lone pairs

Answer 19

linear - 180°

Question 20

5 bonding pairs 1 lone pair

Answer 20

square pyramidal - 89°

Question 21

4 bonding pairs 2 lone pairs

Answer 21

square planar - 90°

Question 22

when does hydrogen bonding occur

Answer 22

Strongest IMF
Occurs between H atom bonded to O/N/F

Question 23

How does Hydrogen bonding arise?

Answer 23

• there is a large difference in electronegativity between O atom and the H atom in the OH bond
• this polarises the OH bond
  there is a strong attraction between the lone pair of O atom
• lone pair of O atom and partially positive H atom on another molecule

Question 24

when does permanent dipole dipole occur

Answer 24

Generally weaker than hydrogen bonding between polar molecules

Question 25

How does permanent dipole dipole arise

Answer 25

• there is a difference in electronegativity between the chlorine atom and hydrogen atom
• this polarises the H-Cl bond forming a dipole.
• Dipoles do not cancel out as the molecule is asymmetrical
• there is an attraction between the partial positive H atom and partial negative chlorine on another molecule

Question 26

when does van der waals forces occur

Answer 26

the weakest but can be the stronger than H bonding or P.D.D if molecule is larger
occurs between all simple molecules
is the most important IMF for non polar molecules that cannot form H bonds/P.D.D

Question 27

How does van der waals arise?

Answer 27

• Random movement of electrons in a molecule causes uneven distribution of electrons
• this forms a temporary dipole
  this induces