Chemistry #2 Flashcards
Cations
Ions which are positively charged
Anions
Ions which are negatively charged
What are ionic compounds?
Ionic compounds form crystal lattices
What are crystal lattices?
Crystal lattices are a repeated arrangement of ions in 3d
What charge are ionic compounds?
Ionic compounds are neutral charge, the + charge of the cations and - charge of the anions cancel out
Ionic bonds
They are very strong
What are the properties of ionic compounds
They are hard, brittle and also have higher melting points
How do ionic compound form?
When cations and anions come together, the metal atom will need to lose a electron whilst the non-metal will need to gain an electron so they share their electrons. When the electron is transferred, they both form into ions, and are pulled together by electrostatic attraction.
Naming ionic compounds
First you would put the positive ion and then the negative ion like calcium fluoride, not fluoride calcium
How to write it
In the name you would not put the ion’s charge,
For example, calcium ions have a charge of +2, while fluoride ions have a charge of −1. If there was only one Ca
2+
ion and one F
−
ion, the overall charge would be +1. There must be two F
−
ions and one Ca
2+
ion in calcium fluoride to balance the charge.
The ionic formula for calcium fluoride is CaF
2
. The subscript 2 tells you that there are 2 fluoride ions. If there is no subscript number it tells you that there is only one of these ions.
Naming
To figure out what the chemical formula for an ionic compound will be, you first need to determine the charge on the ions that make it up.
You then need to determine how many of each type of ion are needed to make the overall compound neutral.
More naming
The swap and drop method is where you swap the numbers from the charges on the ions, then drop these numbers to give you the number of each type of ion in the compound. Putting these together then gives you the ionic formula.
For example, the ionic compound aluminium oxide is made up of Al 3+ and O 2− ions. Its ionic formula is Al 2 O . This gives 6 positive charges and 6 negative charges to make the overall compound neutral.
