Bonding, Structure and Properties of matter Flashcards
What are ions?
charged particles
What is made when electrons are transferred?
ions
What happens when metals form ions?
They lose electrons from their outer shells to form positive ions.
What happens when non-metals form ions?
They gain electrons into their outer shells to form negative ions.
What charged ions do metals form?
positive
What charged ions do non-metals form?
negative
What is ionic bonding?
When a metal and non-metal react together. The metal loses electrons and the non-metal gains these electrons.
What are oppositely charged ions strongly attracted to one another by?
electrostatic forces of attraction
What is the attraction between oppositely charger ions called?
An ionic bond
What groups are most likely to form ions?
1&2 and 6&7
What are positive ions called?
cations
What are negative ions called?
Anions
Draw a dot and cross diagram for sodium chloride.
Your diagram should show:
Sodium loses 1 electron from its outer shell, forming a +1 charged ion.
Chlorine gains the electron into its outer shell, forming a -1 charged ion.
Draw a dot and cross diagram for magnesium chloride.
Your diagram should show:
Magnesium loses two electrons from its outer shell, forming a +2 charged ion. Each chlorine atom gains one electron into its outer shell forming a -1 charged ion.
What structures are ionic compounds?
Regular lattice structure/ giant ionic lattice
What are the properties of ionic compounds?
High melting and boiling points
(strong bonds means lots of energy needed to break them)
Can’t conduct electricity when solid
When melted, can carry electric current
Some dissolve easily in water
What two ways can ionic compounds conduct electricity?
When melted/molten
When dissolved in water
What is covalent bonding?
When non-metal atoms bond together, they share electrons.
True or false: Covalent bonds are weak.
False- covalent bonds are strong as the positively charged nuclei of the bonded atoms are attracted to the shared pair of electrons by electrostatic forces.
Complete the sentence: Each single covalent bond provides _______ extra shared ______ for each atom.
one, electron
True or false : Covalent bonds fill up the atom’s outer shell making it very stable.
True
What are the different ways of drawing covalent bonds?
- Dot and cross diagrams
- Displayed formulas
- 3D Models
What are the factors of a giant covalent structure?
- High melting and boiling points
- Don’t conduct electricity (no charged particles) except graphite
What type of structures do covalent bonds usually have?
simple molecular structures
In simple molecular structures, what are the atoms held together by?
very strong covalent bonds
How strong are the forces of attraction in simple molecular structures?
very weak
What are the properties of simple molecular structures?
- Low melting and boiling points due to weak forces of attraction
- mostly gases or liquids at room temp
- As molecules get bigger, forces increase so melting and boiling points increase
- Don’t conduct electricity
Give two examples of giant covalent structures.
Diamond and Graphite
What are the properties of diamond?
- Strong covalent bonds so high melting and boiling point
- Doesn’t conduct electricity
- Very hard as each carbon atom forms 4 covalent bonds
How many covalent bonds does each carbon atom in diamond form?
4
Why does diamond not conduct electricity?
There are no free electrons (delocalised) or ions
How many covalent bonds does each carbon atom in graphite form?
3
What are the properties of graphite?
- Soft & slippery
- high melting point
- good conductor of heat and electricity
Why can graphite conduct electricity?
Each carbon atom only forms three covalent bonds, so each atom has one delocalised electron that is free to move. Therefore charge can flow so it conducts heat and electricity.
Why is graphite slippery?
There aren’t any covalent bonds between the layers so they are weakly held together meaning they can move over each other.
What is graphene?
A sheet of carbon atoms joined together in hexagons.
What is a polymer?
Long chains of repeating units
What are atoms in a polymer joined by?
Strong covalent bonds
Do polymers have higher or lower boiling points than ionic compounds?
Low - weak intermolecular forces
What state are most polymers at room temperature?
Solid- larger intermolecular forces than simple covalent molecules
What are giant covalent structures?
All atoms are bonded to each other by strong covalent bonds.
What are giant covalent structures also known as?
Macromolecules
What are the properties of giant covalent structures?
- Very high melting and boiling points
- Don’t conduct electricity, except graphite
What are allotropes?
Different structural forms of the same element in the same physical state.
Give 3 examples of carbon allotropes.
Diamond, Graphite, Graphene
What are fullerenes?
Molecules of carbon, shaped like closed tubes or hollow balls.
In fullerenes, what are the carbon atoms typically arranged in?
hexagons but can contain pentagons or heptagons
What was the first fullerene to be discovered?
Buckminsterfullerene
Why can fullerenes be used in medicine?
They can be used to cage other molecules, this can be used to deliver a drug into the body.
Why do fullerenes help to make good catalysts?
They have a huge surface area, individual catalyst molecules could be attached to them.
Complete the sentence : Fullerenes make good l___________.
lubricants
What can fullerenes form (tiny carbon cylinders)?
nanotubes
What are nanotubes?
Tiny carbon cylinders
What are the properties of nanotubes?
- Conduct electricity and heat
- High tensile strength
- High ratio of length and diameter
How can nanotubes be used in technology?
They can strengthen materials without adding much weight.
What is the name of the technology involving nanotubes?
nanotechnology
What is metallic bonding?
Bonding between two metals
Electrons in the outershell are delocalised
What are the forces of attraction in metallic bonding?
Strong forces of electrostatic attraction between positive ions and negative electrons
What are the properties of metals?
- Solid at room temp
- High melting and boiling points
- Good conductors of electricity and heat
- Malleable
Why are most metals malleable?
The layers of atoms slide over each other.
Why are alloys harder than pure metals?
Pure metals are often too soft. When pure metals are mixed with other elements, the layers of metal atoms are distorted making it more difficult for them to slide over each other.
What is an alloy?
A mixture of two or more metals or a metal and another element.
What are the three states of matter?
Solid, Liquid, Gas
What does the state of something depend on?
How strong the forces of attraction are between the particles of the material.
What does the strength of forces in an atom depend on?
- The material (structure & bonds)
- The temperature
- The pressure
Describe the structure of a solid.
- Strong forces of attraction between particles
- Fixed position forms a regular lattice arrangement
- Definite shape and volume
- Vibrate about their positions
Describe the structure of liquids.
- Weak forces of attraction
- Randomly arranged and free to move
- Definite volume but not definite shape
- Constantly moving with random motion
Describe the structure of gases.
- Very weak forces of attraction
- No definite shape or volume
- Constantly moving with random motion
Describe the change from a solid to a liquid.
Melting:
- Solid is heated, particles gain more energy
- Particles vibrate more, weakening the forces of attraction
- At the melting point, particles break free and form a liquid
Describe the change from a liquid to a gas.
Boiling:
- Liquid is heated, particles gain more energy
- Particles move faster, weakens and breaks the bonds holding the liquid together
- At boiling point, particles break bonds forming a gas
Describe the change from a gas to a liquid.
Condensing:
- As gas cools, particles lose energy so don’t have enough to overcome forces of attraction
- Bonds form between particles
- At boiling point, so many bonds have formed causing the particles to become a liquid
Describe the change from a liquid to a solid.
Freezing:
- Particles have less energy so move around less
- Not enough energy to overcome forces of attraction
- At melting point, bonds have formed and are held in place, particles become a solid
What are coarse particles?
Particles with a diameter between 2500nm and 10,000nm.
Also called dust.
What are fine particles?
Particles with a diameter between 100nm and 2500nm.
What are nanoparticles?
Particles with a diameter between 1nm and 100nm.
List coarse particles, nanoparticles and fine particles in order of size. Start with the smallest.
Nanoparticles (1x10^-9m), Fine particles (1x10^-7m), Coarse particles (1x10^-5m)
What do nanoparticles have?
A large surface area to volume ratio.
What is the equation for surface area to volume ratio?
Surface area/ volume
Give 5 uses of nanoparticles.
- Catalysts
- Nanomedicine
- Electric circuits
- Added to polymer fibres to make surgical masks, wound dressings and deodrants
- Cosmetics
True or false: Nanoparticles can conduct electricity.
True
Why are some people against nanoparticles in health/medicine?
The effects aren’t fully understood yet.
