Bonding

Question 1

Ionic bonding

Answer 1

Involves electrostatic attraction between oppositely charged ions in a lattice

Question 2

Formula of sulfate ion

Answer 2

SO4^2-

Question 3

Formula of hydroxide ion

Answer 3

OH-

Question 4

Formula of nitrate ion

Answer 4

NO3^2-

Question 5

Carbonate ion formula

Answer 5

CO3^2-

Question 6

Ammonium ion formula

Answer 6

NH4+

Question 7

Single Covalent bond vs multiple bonds

Answer 7

A single covalent bond contains a shared pair of electrons. Multiple bonds contain multiple pairs of electrons.

Question 8

Co-ordinate bond (dative covalent)

Answer 8

A co-ordinate bond contains a shared pair of electrons with both electrons supplied by one atom.

Question 9

Metallic bonding

Answer 9

Involves attraction between delocalised electrons and positive ions arranged in a lattice

Question 10

What are the four types of crystal structure?

Answer 10

Ionic, metallic, macromolecular (giant covalent), molecular

Question 11

Explain the energy changes associated with changes of state

Answer 11

SOLID —> MELTING = the particles vibrate and gain kinetic energy and the temp rises

MELTING —> LIQUID = all the energy goes into breaking bonds - there is no increase in kinetic energy or temperature

LIQUID —> BOILING = particles moving around, gaining kinetic energy

BOILING —> GAS = bonds are breaking, no increase in kinetic energy or temperature

BOILING —> GAS = particles moving around rapidly & increasing kinetic energy

Question 12

Which repulsion is greater: lone-pair lone-pair, lone-pair bond-pair, bond-pair bond-pair?

Answer 12

BP-BP < LP-BP < LP-LP

Question 13

What is the effect of electron pair repulsion on bond angles?

Answer 13

The greater the repulsion force between two pairs of electrons, the more far apart the two pairs of electrons will be and hence the larger the bond angle between them.

Question 14

Electronegativity

Answer 14

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

Question 15

Explain why some molecules with polar bonds do not have a permanent dipole

Question 16

Explain the electron distribution in a covalent bond between elements with different electronegativities

Answer 16

The electron distribution in a covalent bond between elements with different electronegativities will be UNSYMMETRICAL. This produces a polar covalent bond, and may cause a molecule to have a permanent dipole.

Question 17

Name three forces between molecules

Answer 17

• permanent dipole-dipole forces
  -induced dipole-dipole (van der Waals, dispersion, London) forces
  -hydrogen bonding

The MP and BP of these molecular substances are influenced by the strength of these IMFs.

Question 18

What is the importance of Hydrogen bonding in the low density of ice?

Answer 18

When water freezes, the water molecules are no longer free to move about and and the hydrogen bonds hold the molecules in fixed positions. In order to fit into this structure, the molecules are slightly less closely packed than in liquid water. This means ice is less dense than water.

Question 19

How do lone pairs affect bond angles?

Answer 19

Lone pairs are more repulsive than bonding pairs as a result of being closer to the nucleus of the atom. This distorts the basic shape and reduces the bond angle by 2.5 degrees

Question 20

Importance of hydrogen bonding in the anomalous boiling points of compounds

Answer 20

The boiling points of NH3, H2O and HF are all higher than those of the hydrides of the other elements in their group. This is because hydrogen bonding is present in NH3, H2O and HF, and it is stronger than dipole-dipole forces.

Question 21

Examples of ionic crystal structures