S2.1: The Ionic Model Flashcards
What is ionic bonding?
One definition:
The force of attraction between oppositely charged ions
Involves transfer of electrons
Electrostatic attractions are formed
Very strong, need a lot of energy to overcome
Form regular lattice
Metal + nonmetal
What is electronegativity?
The ability of an atom to attract a pair of electrons towards itself in a covalent bond
Why do ionic bonds form?
Due to a large difference in electronegativity (>1.8)
Result of positive nucleus ability to attract negative electrons in the outer shell towards itself
Metal -> low electronegativity
Nonmetal -> high electronegativity
Properties of ionic compounds
Strong -> electrostatic forces
High mp and bp -> electrostatic forces, increase with charge density
Not volatile
Solid at room temp
Brittle (shatter when force is applied) -> ionic crystal structure
Do not conduct in solid state
Conduct in molten/dissolved state -> ions/electrons are free
Soluble in water
How does the structure of ionic compounds affect solubility?
Affected by:
strength of ionic bond
interactions with solvent
Charge density -> less charge (weaker forces) more soluble
Size of ion -> 2 big ions bonded are more soluble bc not as nicely packed than big and small ion
What happens in a single replacement reaction?
One element replaces another in a compound
Metals replace metals,
Nonmetals replace nonmetals
Reactivity series -> determines if reaction occurs
Ex:
2 K + 2 H2O -> 2 KOH + H2
What happens in a double replacement reaction?
Two compounds exchange ions to form two new compounds
Often results in formation of a precipitate
NaCl + AgNO3 -> AgCl + NaNO3
What is a net ionic equation?
Équation of a reaction that shows only the ions involved in the reaction
Spectator ions eliminated
Helps focus on key chemical change
Reactivity series of metals
Potassium
Sodium
Lithium
Calcium
Magnesium
Aluminum
—————
Carbon
—————
Zinc
Iron
—————
Hydrogen
—————
Copper
Silver
Gold
More reactive elements replace less reactive ones in a replacement reaction
What is an ionic bond?
Electrostatic attraction between cation and anion
The sum of the electrostatic attraction and repulsive forces between all ions the lattice
What is lattice enthalpy?
Lattice dissociation enthalpy (ΔH_latt^llllll (but horizontal)):
The standard enthalpy change that occurs on the formation of 1 mol of gaseous ions from the solid lattice
Lattice enthalpy in ionic -> high -> responsible from many of ionic compound properties
Always endothermic:
Energy needed to break bonds -> energy in -> enthalpy change is positive
How does ionic radius and charge effect lattice enthalpy?
Smaller ion -> greater lattice enthalpy
Greater charge -> greater lattice enthalpy
