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Bonding- the basics
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What is ionic bonding between?
A metal and a non-metal
Do metal ions become positive or negative?
Positive
Do non-metal ions become positive or negative?
Negative
What is the name for a positive ion?
Cation
What is the name for a negative ion?
Anion
Do metal atoms become smaller or larger after ionic bonding? Why?
Smaller
Loses electron(s) and becomes cation
Nucleus same charge
Electrostatic force to each electron is greater
Electrons pulled closer so radius is reduced
Do non-metal atoms become smaller or larger after ionic bonding? Why?
Larger
Gains electron(s) and becomes anion
Nucleus same charge
Electrostatic force to each electron is smaller
Electrons drift futher so radius is increased
Give the definition for
electron affinity
.
The
energy change
when one mole of
gaseous atoms
acquires
one mole of
electrons
to form one mole of
gaseous negative ions
(anions).
Give the name of the structure that ionic compounds form.
Giant ionic crystal lattice
Give four properties of ionic compounds.
Very high melting points
Strong but brittle
Only conduct electrivity when aqeous or molten
Insoluble in non-polar solvents (water is polar)
Do ionic compounds have high or low melting points? Why?
Very high melting points.
Because:
Very strong ionic bonds
Very strong electrostatic forces
Forms giant ionic crystal lattice
Lots of energy needed to separte ions
Are ionic compounds weak or strong? Brittle or malleable? Why?
Strong and brittle.
Brittle:
Dislocate one layer
Layer moves
Similar ions become adjacent
Electromagnetic replusion between similar ions
Crystal splits
Can ionic compounds conduct electricity?
Only when aqueous (dissolved) or molten (liquid state).
Ionis able to move
So able to carry current
Are ionic compounds soluble? If so in what solvents? Why?
Only soluble in non-polar solvents (water is polar).
Lots of energy needed to overcome electrostatic attraction
Polar molcules surrond ions
Separate ions
What is metallic bonding between?
Two metals
Draw a metallic compound
Give four properties of metallic compounds.
Malleable (and ductile)
High melting point
Conduct electricity
Lustre
Are
metallic compounds brittle or malleable? Why?
Malleable.
Cations in 'sea' of delocalised electrons
Shift cation layers
Electrons still there
Electrostatic forces still there
Do metallic compounds have a high or low melting point? Why?
High melting point.
Cations in 'sea' of delocalised electrons
Strong electrostatic forces
Lots of energy needed to seperate cations
In metallic compounds, what factors make a difference to the boiling point of the compound? And why?
Radius of the ions:
Smaller means cations closer together
Stronger electrostatic forces
Number of electrons 'donated' from each atom:
More means stronger electrostatic force
Do metallic compounds conduct electricity? Why?
Yes.
Conduction of electicity needs freedom of movement for charged particles
Delocatlised electrons can move
What is the name for when a metal shines?
Lustre
Are metallic compounds lustrous? Why?
Yes.
Cations in 'sea' of delocalised electrons
Electrons easily absorb and re-emit photons of visable light
Smoother the surface=more lustrous
What is covalent bonding between?
Two non-metals
What is a covalent bond?
A shared pair of electrons between two atoms.
What is a intramolecular bond?
A bond between atoms.
What is an intermolecular bond?
A bond between molecules.
How do you show a lone pair of electrons on a stick diagram?
As two dots.
Do covalent compounds have a high or low boiling point? Why?
Low.
Strong intramolecular bonds
Weak intermolecular bonds
Not much energy needed to seperate molecules for each other
Do covalent compounds conduct electricity? Why?
No.
Molecules neutral overall
No charged particles to carry the current
Author
algebrageek
ID
184628
Card Set
Bonding- the basics
Description
AQA AS Chemistry
Updated
2012-11-27T21:00:36Z
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