4: Chemical bonding

Question 1

What shape of molecule has 2 pairs of electrons?

Answer 1

linear

Question 2

What shape of molecule has 3 pairs of electrons?

Answer 2

trigonal planar

Question 3

What shape of molecule has 4 pairs of electrons?

Answer 3

tetrahedral

Question 4

What shape of molecule has 5 pairs of electrons?

Answer 4

trigonal bipyramidal

Question 5

What shape of molecule has 6 pairs of electrons?

Answer 5

octahedral

Question 6

what combination of lone/bonding pairs repel each other the strongest?

Answer 6

lone pair - lone pair

Question 7

what combination of lone/bonding pairs repel each other the weakest?

Answer 7

bonding pair - bonding pair

Question 8

What is the formula to calculate bond order?

Answer 8

bond order = 0.5 x ( no. of bonding electrons - no. of antibonding electrons)

Question 9

What is a covalent molecule consisting of two atoms of the same element called?

Answer 9

homonuclear diatomic molecule

Question 10

what is the opposite of a homonuclear diatomic molecule

Answer 10

heteronuclear diatomic molecule

Question 11

what is the symbol for electronegativity?

Answer 11

χ (chi)

Question 12

how does covalent character in an ionic bond arise?

Answer 12

Ionic bonds acquire covalent character if the positive ion can attract electron density from the negative ion towards itself and into the internuclear region. The valence electrons are then partially shared giving some covalency to the bonding.

Question 13

The polarising power of the positive ion depends on what?

Answer 13

charge and size

Question 14

what is the relationship between charge density and the polarising power of the cation

Answer 14

greater charge density = more polarising

Question 15

what increases the polarisability of an anion

Answer 15

Polarisability increases as the negative charge on the anion increases, and as the number of electrons (in other words the anion’s size) increases.