Molecular shape and bonding

Question 1

Describe ionic bonding

Answer 1

• Electrons transferred between a metal and a non-metal
• Electrostatic attraction holds ions together

Question 2

Describe metallic bonding

Answer 2

Electrons pooled between a metal and another metal

Question 3

Describe pure covalent bonding

Answer 3

Electrons shared equally between two non-metals

Question 4

Describe polar covalent

Answer 4

Electrons shared unequally between two non-metals

Question 5

Properties of ionic compounds.

Answer 5

• Larger ion, weaker attraction and hence
  lower lattice energy.
• Larger charge, stronger attraction and
  hence higher lattice energy.
• Ionic compounds have high melting points
  (and boiling points).
• All ionic compounds are solids at room temperature.
• Hard and brittle crystalline solids – many are soluble in water.

Question 6

How do you calculate formal charge?

Answer 6

Number of valence electrons - (number of lone pair of electrons + 0.5 x number of bonding electrons)

Question 7

What is a free radical?

Answer 7

Species where one atom has a single unpaired electron

Question 8

How can bonds be polar?

Answer 8

The electrons are shared unequally due one atom being more electronegative than the other

Question 9

What is meant by electronegativity?

Answer 9

The ability of an atom to pull bonding electrons towards itself

Question 10

What is the most and least electronegative element.

Answer 10

Fluorine - most
Cesium - least

Question 11

Describe p-orbitals.

Answer 11

• Dumbbell shaped
• A nodal plane that ‘cuts’ the dumbbell into two lobes

Question 12

Describe the three 2p orbitals.

Answer 12

• x, y and z
• each one is perpendicular to the other 2

Question 13

Compare the energy of 2p and 2s.

Answer 13

energy of 2p > energy of 2s because 2p atomic orbital is farther away from the nucleus

Question 14

Describe MO theory.

Answer 14

• Nuclei are held together by molecular orbitals
• A MO is an electron distribution with electron density over the whole molecule

Question 15

Compare anti-bonding orbital to a bonding orbital.

Answer 15

• Anti-bonding orbital has a node of electrons likely to be found anywhere but between the nuclei WHEREAS in bonding orbital it is most likely to be found between the nuclei
• Energy of electrons in bonding orbitals < energy of electrons in the anitbonding orbitals