Ionic Bonding Flashcards
What is ionic bonding
The transfer of electrons from a metal atom to a non-metal atom to form positive metal ions and negative non-metal ions. This results in strong electrostatic forces between oppositely charged ions in a lattice
Which model is used to show ionic bonding
Dot-and-cross diagrams
What is a lattice
Regular 3D repeating arrangement of ions in a crystal
Which ions produce the strongest electrostatic attractions
Ions with high charges and small ionic radii(those with a high charge density)
Which ions produce the weakest electrostatic attractions
Those with low charges and big ionic radii(low charge density)
Do compounds with stronger or weaker ionic bonds have a greater solubility in water
Compounds with weaker ionic bonds-weaker force of electrostatic attraction between ions means these are easier to break apart
Properties of ionic compounds
-hard and brittle
-high melting and boiling temperatures
-soluble in water and other polar solvents,insoluble in non-polar solvents
When do ionic compounds conduct electricity and why
When melted or dissolved in water because charged ions are then free to move, when solid their ions cannot move away from fixed positions in the giant lattice
What is electrolysis
The decomposition of a compound by electricity
What is an electrolyte
The compound which is being decomposed by electrolysis, described as being electrolysed
Which ions move towards the cathode and what happens there
Cations(positive ions) move towards the cathode(negative electrode) where they gain electrons to form their element
Which ions move towards the anode and what happens there
Anions(negative ions) move towards the anode(positive electrode) where they lose electrons to form their element
What evidence is there for ionic bonding
Can look at electron density maps (show likelihood of finding electrons in a region). Show electrons are discrete(separate) as electron density falls to zero between ions and ions are arranged in regular patterns (lattice structure)
What does isoelectronic mean
When atoms/ions have the same number of electrons and so same electronic configuration
How does the size of radius change when atoms form positive ions
Ionic radius for positive atoms is smaller than atomic radius as electrons are lost from its outer shell
How does size of radius change when atoms form negative ions
Ionic radius of negative ions is greater than atomic radius as electrons are added to its outer shell
How does ionic radius change down a group
Ionic radius increases as there are more electron shells meaning more shielding which decreases the attraction between nucleus and outer electrons and the outer electrons are not pulled in as much and more electron shells so ion bigger
How does ionic radius change across period
Ionic radius decreases in size as number of protons increases while shielding does not increase significantly as electrons are added to the same shell meaning electron shells are pulled closer
Why are ionic compounds soluble in water
Water molecules are polar meaning they can attract both positive and negative ions and break down the structure
Why are ionic compounds brittle
When struck the layers slide so get positive ions aligned with positive ions and negative ions aligned with negative ions which repel each other meaning the structure breaks apart
Why does a smaller ionic radii increase melting point
Stronger electrostatic attractions between ions as they can be packed together more closely meaning more energy is required to overcome stronger forces
Evidence for ions from coloured ionic compounds
Electrolysis of coloured ionic compound on wet filter paper, ions will move towards electrode with opposite charge showing evidence for charged particles
