Module 2.2 Electrons, Bonding and Structure

The shell that the electrons occupy

The further the shell is from the nucleus and the higher the energy level

2

8

18

32

Hold a max. of 2 electrons with opposite spins An orbital is a region of space where electrons are most likely to be found

s p d f

Spherical shape Can hold 2 electrons

3D dumbbell shape Can hold 6 electrons

1s 2s 2p 3s 3p 4s 3d 4p 4d 4f

The lowest energy level is filled first Each energy level must be full before the next higher energy level starts to fill Each orbital is filled singly before pairing starts The 4s orbital is at a slightly lower energy level than the 3d orbital. Therefore, 4s fills before 3d

Electrons in the highest energy levels are lost first

Metal + non-metal Electrons are transferred from the metal atom to the non-metal atom Oppositely charged ions formed that attract each other

Two non-metals Electrons are shared between the atoms and are attracted to the nuclei of both bonded atoms

Occurs in metals Electrons are shared between all atoms

Electrons are transferred from the metal atom to the non-metal atom Oppositely charged ions form, which are bonded together by electrostatic attraction The metal ion is positive (cation) The non-metal ion is negative (anion)

Each ion is surrounded by oppositely charged ions These ions attract each other from all directions, forming a 3D giant ionic lattice All ionic compounds exist as giant ionic lattices in the solid state but when aqueous, the ions are free to move so they can conduct when aqueous or molten

Ionic compounds are solids at room temperature- a large amount of energy is needed to break the strong electrostatic bonds that hold the oppositely charged ions together in the lattice. Therefore, ionic compounds have high melting and boiling points. The greater the charge, the stronger the electrostatic forces between the ions so more energy is required to break up the ionic lattice during melting

In a solid ionic lattice: The ions can’t move - can’t conduct When aqueous or molten: The solid lattice breaks down - the ions are free to move Can conduct

The slight charges within the polar substances are able to attract the charged ions in the giant ionic lattice. This means that the lattice is disrupted and the ions are pulled out of it.

The negatively charged shared pair of electrons is attracted to the positive charges of both nuclei This attraction overcomes the repulsion between the two positively charged nuclei Electrons are shared

4 covalent bonds

3 covalent bonds