5)Electrons, Bonding and Structure

• What is an orbital?

  A region of space that can hold up to 2 electrons with opposite spins.
• How many electrons occupy each of the first 3 shells?

  1st shell : 2 electrons

  2nd shell : 8 electrons

  3rd shell : 18 electrons
• How many electrons can occupy the p-subshell?

  6 electrons (have 3 atomic orbitals - the shape of p-orbitals are dumbbell shaped).
• How many electrons can occupy the s-subshell?

  2 electrons (have 1 atomic orbital - the shape of s-orbital is a spherical shape)
• What subshells make up the third shell?

  s, p and d sub shells
• How many electrons can an orbital hold?

  An orbital can hold up to 2 electrons with opposite spin
• How are atomic orbitals arranged into subshells and shells?

  • Atomic orbital with the same energy are grouped together into subshells.
  • Subshells of similar energy are grouped together into shells.
• Why do the electrons in an atomic orbital have opposite spins?

  Electrons in an atomic orbital have opposite spin to minimise the repulsion between electrons.
• The order that electrons are added to and removed from the 3d and 4s subshells:

  • Electrons are added to the 4s subshell before they are added to the 3d sub shell.
  • Electron are removed from the 4s sub shell before they are removed from the 3d sub shell.
• The order of removing electron from the 4s and 3d subshells when forming a positive ion:

  When forming a positive ion, the 4s orbital empties before the 3d orbitals.
• Name the four types of subshells:

  s, p, d and f subshells
• What is an ionic bod?

  An ionic bond is the strong electrostatic force of attraction between oppositely charged ions.
• Why do atoms form ions?

  Atoms forms ions so that they can gains a full outer shell of electrons, which make them more stable.
• What is an ionic dot and cross diagram?

  A diagram that shows the ionic bonding by showing how the electrons are transferred to form ions.
• What is an ion?

  An ion is a charged atom or molecule.
• Why don't group 0 element form ions?

  Group 0 elements do not form ions because they already have a full outer shell of electrons.
• Physical properties of ionic compounds:

  • High melting and boiling point
  • Conduct electricity only in the liquid molten (l) or aqueous states, but not when solid.
  • Soluble in water.
• Structure and bonding of an ionic compound:

  • Ionic compounds have a giant ionic lattice structure, which has strong electrostatic forces of attraction between oppositely charged ions.
• Why are ionic compounds non-volatile.


  The strong ionic bonds (electrostatic force of attraction between oppositely charged ions) require a lot of energy (and therefore a high temperature) to break.
• When do ionic compounds conduct electricity, and why?

  • Ionic compounds only conduct electricity when molten or aqueous, but not when solid.
  • This is because, in these state, the ions are free to move and carry the charge - need charged particles that are free to move in order to conduct electricity.
• What is a compound ion?

  A compound ion is an ion containing atoms of more than one element bonded together.
• Why do ionic compounds have no overall electrical charge?

  • Ionic compounds are made up of oppositely charged ions,
  • Where the sum of the positive charge = the sum of the negative charge.
• What is an anion?

  A negatively charged ion.
• What is a cation?

  A positively charged ion.
• What is a covalent bond?

  A covalent bond is the electrostatic attraction between a shared pair of electrons and the nuclei of the 2 bonded atoms.
• Why do simple molecular substances have a low melting and boiling point?

  The intermolecular forces between the molecules are weak, so only a small amount of energy is required to overcome it.
• Are covalent bonds or intermolecular forces stronger?

  Covalent bonds are much stronger.
• • Covalent bonds form between 2 non-metal atoms.
• What is a dative covalent bond?

  A dative covalent bond is a covalent bond in which the electrons in the bond comes from one of the atoms in the bond.
• Requirement for the formation of a dative covalent bond between 2 atoms:

  1. One atom must have a lone pair of electrons that is used in the bond.
  2. The other atom must have an incomplete electron shell.
• How are dative covalent bonds represented.

  A dative covalent bond is represented by an arrow, pointing towards the atom that is accepting the electron pair.
• Why do simple molecular substances not conduct electricity in any state?

  Molecules cannot conduct electricity because they do not have an overall electrical charge.
• Why do simple molecular substances have a low melting point?

  They have weak intermolecular forces between molecules which require little energy to overcome.
• Describe the structure of metals:

  • Metals have a giant metallic lattice structure consisting of metal cations, arranged in a regular pattern.
  • The outer electrons of each metal atoms leave to become delocalised, therefore they are able to move freely between the cations in the lattice structure.
• What is a metallic bond?

  A metallic bond is the strong electrostatic force of attraction between the metal cations and the delocalised electrons.
• Explain the factors that determine the strength of the metallic bond:

  • Number of delocalised electrons per atom - leads to a stronger metallic bond due to stronger electrostatic attraction between metal cation and the delocalised electrons.
  • Charge of the metal cation - greater the charge of the metal cation, the stronger the electrostatic attraction between cations and delocalised electrons.
  • Size of the metal cation - the smaller the metal cation, the closer the delocalised electrons are to the positive nucleus, therefore the stronger the metallic bond.
• Why do metals have a high melting and boiling points?

  High temperature are required to provide a lot of energy that is needed to overcome the strong electrostatic force of attraction between the metal cation and the sea of delocalised electrons.
• Why are metals good at conducting electricity?

  They have delocalised electrons that can move through the structure, carrying the charge when a voltage is applied (,and heat energy).
• Why are metals malleable/ ductile?

  The layers of metal cations can slide over each other when an external force is applied.
• Are metal soluble?

  • Do not dissolve
  • But interaction would lead to a reaction ( a metal hydroxide is formed, which then dissolves in the water)