ionic bonding Flashcards
define ionic bonding
an electrostatic force of attraction between th oppositely charged ions
how is an ionic bond formed?
. when electrons are transferred from a metal to a non-metal forming oppositely charged ions
. metals loose and become positive non-metals gain and become negative
describe the structure of NaCl
. giant ionic lattice
.has oppositely charged ions in a giant lattice network
held together by a strong electrostatic forces of attraction between oppositely charged ions
what are the properties of ionic compounds
high MP + BP
how does ionic charge affect the MP and BP of init compounds?
IONIC CHARGE
-the greater the charge on the ions the stronger the electrostatic forces of attraction between oppositely charged ions
-the greater the energy required to overcome these forces
greater the charge on ions the higher the MP and BP
EG; MgCl>NaCl - Mg2+ 2CL- vs Na+ Cl-
what factors affect the melting point of ionic compounds
IONIC CHARGE - greater the charge on ions the higher the MP and BP
IONIC RADIUS - The smaller the ionic radius, the stronger the electrostatic forces of
attraction between the oppositely charged ions, and the higher the melting points.
what is an ionic lattice
. in ionic compound millions and millions of ions are packed together in a regular cubic arrangement, joined by ionic bonds
. this from the 3D structure known as an ionic lattice
. the attractive electrostatic forces between the oppositely charged ions are very strong and hold the lattice together.
how does ionic radius affect the MP and BP of in it compounds?
The smaller the ionic radius, the stronger the electrostatic forces of attraction between the oppositely charged ions, and the higher the melting points.
compare the melting points of the following ionic compounds and arrange them in order of increasing melting points (4 marks)
Na2O, K2O, Rb2O
- all three have the same anion O2-
- they all contain cations from the same group and therefore they all have the same charge 1+
- when going down the group the atomic radius increases
- so as you go down the group the electrostatic forces of attraction between the group 1 cations and the anion would decrease
- therefore less energy is needed to overcome the forces as you move down group one
ion radius Na2O > K2O > Rb2O
Na2O - highest MP Rb2O - lowest MP
compare the melting points of the following ionic compounds and arrange them in order of increasing melting points (4 marks)
NaCl, MgCl2, AlCl3
- they share the same anion with the charge 1-
- the cations are in different groups but same period 3
- as you go across period 3 the ionic radius decreases and the charge increases
- there is a strong electrostatic force of
attraction between the cations of period 3 and the negative chloride ion increases. - Therefore, more energy is needed to overcome the strong electrostatic forces of
attraction as you go across the period.
Ionic charge: Na+ < Mg2+ < Al3+
Ionic radius: Na+ > Mg2+ > Al3+
Melting point: NaCl < MgCl2 < AlCl3
Lowest melting point highest melting point