2.2.2 Bonding and Structure Flashcards
What is ionic bonding present in?
in compounds usually consisting of a metal and a non metal
Definition of ionic bonding
its the electrostatic attraction between positive and negative ions
dot and cross diagram for of Na2O (ionic bonding)
draw it
how is a giant ionic lattice formed?
Each ion is surrounded by oppositely charged ions. These ions attract each other from all directions, forming a three dimensional giant ionic lattice.
3 properties of ionic compounds
> high melting and boiling points
cannot conduct electricity
is soluble in polar substances
why do ionic compounds have high melting and boiling points?
large amount of energy is needed to break the strong electrostatic bonds that hold the oppositely charged ions together in the solid lattice.
how does the charge affect the melting point?
the greater the charge, the stronger the electrostatic forces between the ions therefore more energy is required to break up the ionic lattice
Why do solid ionic lattice not conduct electricity?
because the ions are held in fixed positions and no ions can move
describe an ionic lattice as been soluble
it can dissolve in polar substances such as water as polar substances have polar bonds.
What are polar bonds?
they occur between atoms that do not share electrons equally, and it results in the atom having very small charge on them
How does an ionic lattice break down in water
> Polar water molecules break down an ionic lattice by surrounding each ion to form a solution.
The slight charges within the polar substances are able to attract the charged ions in the giant ionic lattice.
This means the lattice is disrupted and ions are pulled out of it
What is covalent bonding?
Its the strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms
what is one double bond
when two pairs of electrons are shared between two atoms
what is one triple bond?
when three pairs of electrons are shared between two atoms
what is 2 double bond?
when 2 pairs of electrons are spread between three atoms
what is average bond enthalpy
it allow you to measure the strength of covalent bond
The larger the value of the average bond enthalpy…
… the stronger the covalent bond
What is a dative covalent bond
its when one of the atom supplies both the shared electrons to the covalent bond
what are the types of covalent structures
> A simple molecular lattice
> A giant molecular lattice
what are simple molecular structures made up from?
from small, simple molecules
What are atoms and molecules held together by in simple molecular structures
> Atoms are held together by strong covalent bonds
> Different molecules are held together by weak intermolecular forces (such as van der waals)
properties of simple molecular structures
> Low melting and boiling point
Non conductor of electricity
Soluble
why does simple molecular structures has a low melting and boiling point
because the intermolecular forces are weak so small amount of energy is needed to break them
why is a simple molecular structures a non conductor of electricity
because there are no charged particles free to move
why is a simple molecular structures soluble
its soluble in non polar solvents, such as hexane as the weak van der waals forces are able to form between covalent molecules which helps the molecular to break down and dissolve
properties of giant covalent structures
> High melting and boiling point
non conductor of electricity
insoluble in both polar and non polar
why does a giant covalent structures have a high melting and boiling point
as high temperature is needed to break the strong covalent bonds within the lattice
why is a giant covalent structures a non conductor of electricity
because there are no free particles
why is a giant covalent structures insoluble
because the covalent bonds in the lattice are too strong to be broken
