ELECTRONS AND BONDING Flashcards
As the shell number increases, the energy…
also increases
What is meant by the principle quantum number
The shell number
n
What is the atomic orbital?
The region around the nucleus that can hold up to 2 electrons with opposite spins
What shape is a S orbital?
Spherical
What shape is a P orbital?
Dumbell
What do two electrons in the same orbital do?
Have opposite spins
repulsion
Why is the 4s subshell filled before the 3d subshell?
4s subshell at a lower energy that 3s
So it is filled first
Once filled, energy 3d falls below 4s
So it empties before
What is meant by ionic bonding
The electrostatic attraction between positive and negative ions
The melting point of ionic compounds
High melting and boiling point
High temp needed to provide large quantity of energy which is needed to overcome strong electrostatic attraction between the ions
Why is the melting point higher for lattices with greater charge on the ions?
Because of stronger attraction between ions
Are ionic compounds soluble?
Many dissolve in polar solvents e.g. water
They break down the lattice + surround each ion in solution.
If made of ions with strong charges, attraction too strong to be broken down
What does the solubility of ionic compounds depend on?
Solubility depends on relative strengths attractions within lattice and the attraction between ions and water molecules
Do ionic compounds conduct electricity in a solid state?
No
Ions in fixed position
No mobile charge carriers so doesn’t conduct electricity
Do ionic compounds conduct electricity in a liquid / molten state?
Yes
Solid lattice breaks down
So ions are free to move as mobile charge carriers, so can conduct electricity
Ions in tooth enamel
Ions in tooth enamel are removed in acid conditions.
Gaps can allow toothy decay to develop
Saliva helps neutralize acidic food and replace ions but not always enough so toothpaste contains fluoride ions.
