Structure 2.1 - Ionic Flashcards
Why do atoms bond together?
to decrease their potential energy, into a lower, more stable energetic state
this done by attaining a full outer electron shell
What is the electronegativity in ionic bonding?
Low electronegativity interacting with high electronegativity
What is the electronegativity in covalent bonding?
both atoms have middle-to-high
What is the electronegativity in metallic bonding?
both atoms have low electronegativity
What is the electronegativity of metals and non-metals?
metals - low
non-metals - high/middle to high
What is the Pauling scale and what does it tell us?
rule of thumb to predict a type of bond
if electronegativity difference is over 1.7, it is ionic
if it is under 1.7, it is covalent
What is electronegativity?
a relative measure of the attraction of an atom for a pair of electrons (in a covalent bond)
What determines electronegativity?
effective nuclear charge
What determines 1st ionisation energy?
effective nuclear charge
How is a giant ionic lattice formed?
the electrostatic force of attraction between oppositely charged ions causes them to pack into the ionic lattice with every cation surrounded by anions/vice verse
Why are cations smaller than anions?
because it has formed through the loss of its valence shell
Why are anions larger than cations?
it has gained electrons, which means increased electron-electron repulsion and the expansion of the outer energy level
Which type of ion is smaller?
cation smaller than anion
What is similar about anions ending in -ate?
covalent groups of oxygen and another non-metal
Name 4 properties of ionic substances.
- conduct when molten or in solution, ions feee to move and pass to electrodes in electrolysis
- high m.p and b.p
- hard and brittle
- more soluble in polar than non-polar solvents
What is the lattice enthalpy and what does it measure?
- the energy required to break up 1 mole of an ionic lattice into gaseous ions under standard conditions
- measures stability and strength of an ionic lattice
Is the enthalphy change endothermic or exothermic?
endothermic - positive
What affects the stability of an ionic lattice?
size of the ions - the smaller they are, the more closely they can pack together and attract each other
charge on the ion - the ore charged it is, the stronger the electrostatic force of attraction
Lattice enthalpy is directly proportional to
charge on cation x charge on anion/sum of ionic radii
