m2 - shapes of molecules and ions, electronegativity

Question 1

the shape of a molecule is determined by…

Answer 1

the number of e- PAIRS in the outer shell of the CENTRAL ATOM

Question 2

shape and bond angles of: 2 pairs e-

Answer 2

linear - 180°

Question 3

shape and bond angles of: 3 pairs e-

Answer 3

trigonal planar - 120°

Question 4

shape and bond angles of: 4 pairs e-

Answer 4

tetrahedral - 109.5°

Question 5

shape and bond angles of: 5 pairs e-

Answer 5

trigonal bipyramidal - 90°

Question 6

shape and bond angles of: 6 pairs e-

Answer 6

octahedral - 90°

Question 7

how lone pairs affect shape and bond angles

Answer 7

lone pairs have more energy than bond pairs so push elements closer to each other, making the angle smaller by 2.5°

Question 8

lone pair example - H2O

Answer 8

shape is now non-linear, angle is 104.5 (4 pairs so tetrahedral (109.5) but 2 pairs are lone pairs so you minus 5°)

Question 9

NH3 has 4 pairs in outer shell so would be tetrahedral, but one pair is a lone pair, so angle and shape become

Answer 9

107° (109-2.5) and becomes pyramidal

Question 10

electronegativity is

Answer 10

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

Question 11

purely ionic and purely covalent compound

Answer 11

ionic - FrF (highest difference in electronegativity)
covalent - diatomic eg H-H (same electronegativity)

Question 12

permanent dipole is

Answer 12

a small charge difference across a bond that results from a difference in the electronegativities of the bonded atoms

Question 13

polar covalent bond

Answer 13

has a permanent dipole

Question 14

a polar molecule has

Answer 14

an overall dipole when all permanent dipoles and molecular shape are considered

Question 15

δ+ and δ-

Answer 15

δ+ = element with smaller electronegative value, so will lose e-
δ- = element with larger electronegative value, so will pull e- toward it and gain them