bonding, structure and the properties of matter Flashcards
Which bonding occurs between a metal and a non metal?
Ionic bonding.
What happens to the metal in ionic bonding?
Electrons in the outer shell are lost making it a positive ion.
What happens to the non-metal in ionic bonding?
Gains electrons and becomes a negative ion.
What is an ion?
An atom that has lost or gained electrons.
What are ionic compounds held together by?
Electrostatic, attractive forces between the oppositely charged ions.
Why do forces act in every direction in an ionic compound?
Because it is a 3D structure.
What is covalent bonding?
When atoms share one or more pairs of electrons.
What does metallic bonding consist of?
Positive ions and delocalised electrons arranged in a regular pattern.
Why are delocalised electrons shared in metallic bonding?
To make the metallic bonds strong.
Why do ionic compounds have high melting and boiling points?
As lots of energy is required to break the many strong bonds.
Why can ionic compounds conduct electricity when melted or dissolved in water?
As ions are free to move and can carry current.
Why do small molecules not conduct electricity?
As they don’t have an overall electric charge.
What is broken when boiling/melting small molecules?
The weak intermolecular forces.
Why are polymers solid at room temperature?
As they have relatively strong intermolecular forces.
What is the particle theory?
The amount of energy needed to change state depends on the strength of the forces between the particles.
The stronger the force between particles…
The higher the melting and boiling points of the substance.
Why can metals be bent and shaped?
As layers of atoms can slide over eachother.
What are alloys made from?
2 or more different types of metals.
Why are alloys harder than pure metals?
Different sized atoms distort the structure making it harder for them to slide over eachother.
Why is graphite soft and slippery?
As it has weak intermolecular forces.
How many electrons from each carbon in graphite is delocalised?
1.
What is each carbon in graphite bonded to?
3 other carbon atoms covalently.
What is each carbon in diamond bonded to?
4 other carbon atoms covalently.
What are 3 properties of diamond?
~It is hard
~It has a high melting point
~It doesn’t conduct electricity
What was the first fullerene to be discovered?
Buckminsterfullerene (C60) (with a spherical shape).
What are carbon nanotubes?
Cylindrical fullerenes with high length to diameter ratios.
What can carbon nanotubes be used for?
~Lubricants to deliver drugs in the body
~Reinforcing materials
What is graphene?
A single layer of graphite that is strong but elastic.
How many atoms do nanoparticles contain?
A few hundred.
Why are nanoparticles good catalysts?
They have a high surface area to volume ratio.
Why may nanoparticles be toxic?
As they can enter the brain through the bloodstream.
What are the 5 uses of nanoparticles?
~Used to produce sensors
~Can conduct electricity
~Make stronger and lighter building materials
~Used in cosmetics so they leave no white marks eg. deodorant
~Lubricant coatings
What is a nanoparticle’s size?
1-100nm
What is a fine particle’s size?
100-2500nm
