L7: Ionic Bonding Flashcards
What is the octet rule?
Most atoms show a tendency to adjust their valence shells to 8 e- by losing, gaining, or sharing electrons
What is the most notable exception to the octet rule?
Transition metals using d-orbitals obey the 18 electron rule instead
What is the most electronegative element?
Fluorine - small, high nuclear charge
True or false: Electronegativity increases across a period, and decreases down a group
True
True or false: Ionic bonding involves the sharing of electrons between atoms
False. In ionic bonding one or more electron is fully transferred between atoms
True or false: Ionic bonding takes place between metals and non-metals
True
True or false: Forming an ionic bond involves a decrease in energy compared to the two isolated atoms
True
True or false: Ionic bonds are directional
False
True or false: Ionic compounds disassociate in polar solvents, such as water
True
True or false: Ionic compounds have an overall charge
False. Ionic compounds are neutral
True or false: Ionic bonds are broken when the compound is melted
True
True or false: Ionic compounds form crystalline solids with low melting temperatures
False. They form crystalline solids with HIGH melting temperatures
True or false: Ionic compounds conduct electricity when molten and/or in solution
True
What is ‘lattice energy’?
The enthalpy of forming one mole of the ionic solid from its gaseous ions
True or false: Ionic compounds form giant lattice structures
True
In order to favour ionic bond formation, what electronegativity difference is needed between the cation and the anion?
The larger the better
True or false: To form an anion, a metal should have a low ionisation energy
False. Metals don’t form the anion, they form the cation. And for cation formation, a low ionisation energy is favourable.
True or false: To form an anion, a non-metal should have a high electron affinity
True
When is an ionic compound likely to have some covalent character?
When (a) the cation is small and/or has a high charge; or, (b) the anion is large and/or has a high charge
How do ionic compounds gain some covalent character?
By polarisation - instead of being spherical, the anion loses it’s shape and is pulled towards the cation
What are the five important cations in the body?
1) Sodium
2) Potassium
3) Calcium
4) Hydrogen
5) Magnesium
What are the five important anions in the body?
1) Chloride
2) Bicarbonate
3) Hydrogenphosphate
4) Sulphate
5) Phosphate
