C2 Ionic Compounds Flashcards
What do dot and cross diagrams show?
The arrangement of electrons in an atom or ion.
They can also show what happens to the electrons when atoms react with each other.
What do the dots or crosses represent in a dot and cross diagram?
Each dot or cross represents and electron.
See page 28 for examples of dot and cross diagrams
Example of sodium chloride and magnesium chloride
What kind of diagram shows you how ionic compounds are formed?
Dot and cross diagrams
How do you work out the formula of a compound from a dot and cross diagram?
Write the chemical symbol for each of the different ions (with positive ion first) and show how many of each ion there are.
(See p28 for an example)
What kind of structure do ionic compounds have?
A giant ionic lattice structure.
The ions form a closely packed regular lattice.
Why do the ions form a closely packed regular lattice in an ionic compound?
Because there are very strong electrostatic forces of attraction between oppositely charged ions, in all directions.
What does a ball and stick model show?
How the ions are arranged
What are the short comings of a ball and stick diagram? (What doesn’t it show you?)
The scale is wrong - in reality there aren’t gaps between ions and the ions are different sizes.
What are the short comings of dot and cross diagrams? (What doesn’t it show you?)
They don’t show the structure of the compound.
What properties do all ionic compounds have?
High melting and boiling points.
Solid ionic compounds don’t conduct electricity.
When ionic compounds melt they will carry an electric current.
Many dissolve easily in water.
Why do all ionic compounds have high melting and boiling points?
Because of the strong attraction between the ions.
It takes a large amount of energy to overcome this attraction.
Why don’t solid ionic compounds conduct electricity?
Because the ions are fixed in place and can’t move.
When an ionic compounds melts it will carry an electric current. Explain why.
The ions are free to move and will carry an electric current.
Why do many ionic compounds dissolve in water?
Because their charges allow them to interact with the water molecules.
The ions separate and are all free to move in the solution.
