EL - Ionic bonding Flashcards
What is a compound?
Atoms of different elements bonded together.
What do you get when different elements join or bond together?
A compound.
What are the 2 types of bonding compounds?
Ionic and covalent.
What is ionic bonding?
When ions are stuck together by electrostatic attractions.
How are ions formed?
When electrons are transferred from one atom to another.
What are the simplest ions?
Single atoms which have either lost or gained 1, 2 or 3 electrons so that they’ve got a full outer shell.
If elements in the same group have the same number of outer electrons, what does this mean about the ions they form?
They have to lose or gain the same number to get a full outer shell meaning that they form ions with the same charges.
What ions do group 1 elements form?
1+ ions
What ions do group 2 elements form?
2+ ions
What ions do group 6 elements form?
2- ions
What ions do group 7 elements form?
1- ions
Generally the charge on a metal ion is equal to what?
Its group number.
The charge on a non-metal ion is equal to what?
Its group number minus 8.
What are electrostatic attractions?
The forces that hold positive and negative ions together.
What forces hold positive and negative ions together?
Electrostatic.
How strong are electrostatic forces?
Very strong.
What is it called when electrons are held together by electrostatic forces?
Ionic bonding.
What type of compound are sodium chloride and magnesium oxide?
Ionic compounds.
What is the formula for sodium chloride?
NaCl.
What does the formula of sodium chloride (NaCl) tell you?
It is made up from Na+ ions and Cl- ions in a 1:1 ratio.
What diagrams show how ionic bonding works?
Dot-and-cross diagrams.
What is the overall charge of an ionic compound?
Zero.
Why is the overall charge of an ionic compound 0?
The positive charges in the compound balance the negative charges exactly.
What type of structure does sodium chloride have?
A giant ionic lattice structure.
What are ionic crystals?
Giant lattices of ions.
What is a lattice?
A regular, repeating structure.
Why are giant ionic lattices ‘giant’?
Because it is made up of the same basic unit repeated over and over again.
What do the ions within a lattice do?
Ions with different charges attract each other and the ions with the same charge repel each other.
How do ions within a lattice arrange themselves?
They arrange themselves to maximise the attractions and minimise the repulsions.
What is the overall attraction in the lattice known as?
Ionic bonding.
How do the structures of different ionic compounds differ?
Different ionic compounds have different shaped structures, but they are all still giant lattices.
What decides the physical properties of an ionic compound?
The structure of them.
Do ionic compounds conduct electricity?
When they’re molten or dissolved - but not when they’re solid.
Why do ionic compounds conduct electricity when they’re molten or dissolved - but not when they’re solid?
The ions in a liquid or a solution are free to move (and when they move, their charges move with them). In a solid they’re in a fixed position by the strong ionic bonds.
What is the melting point of ionic compounds like?
High.
Why do ionic compounds have high melting points?
The giant ionic lattices are held together by strong electrostatic forces. It takes lots of energy to overcome these forces, so melting points are very high (e.g. 801 degrees celsius for sodium chloride).
Are ionic compound soluble?
They are often soluble in water.
Why are ionic compounds often soluble in water?
Water molecules are polar - part of the molecule has a small negative charge and the other bits have small positive charges. The water molecules pull the ions away from the lattice and cause it to dissolve.
What are 3 physical properties of ionic compounds?
Conduct electricity when molten or dissolved - but not when they’re solid.
High melting points.
Often soluble in water.
What does ionic structure explain?
The behaviours of ionic compounds.
What does ionic bonding happen between?
A non-metal and a metal.
