Separate Chemistry - 5.2 Flashcards
What type of bond exists between metals and non-metals in a compound?
Ionic Bond
What type of bond exists in non-metal elements and compounds?
Covalent Bond
What type of bonding exists in metallic elements and alloys?
Metallic bonding
What is the name for the electrons that are free to flow in metallic bonding?
Delocalised electrons
What is the name for the forces that exist between ions in an ionic bond?
Electrostatic forces
Q. In which type of bond are electrons shared?
Q. In which type of bond are electrons transferred?
- Covalent bond (electrons shared)
- Ionic bond (electrons transferred)
When atoms gain or lose electrons to become ions, they will have the electron structure of what group of elements?
Noble gases
Q. What charge do metal ions have?
Q What charge do non-metal ions (except Hydrogen) have?
- Metal ions are positive
- Non-metal ions are negative
Describe how sodium and chlorine bond to form sodium chloride.
*this is just an example, you should be able to do this for any metal and non-metal.
- The sodium atom loses one electron to become a sodium ion
- The chlorine atom gains one electron to become a chloride ion
- The positive sodium ion is attracted to the negative chloride ion to form sodium chloride.
Draw dot and cross diagrams for the atoms and ions of the following elements:
a) Magnesium
b) Fluorine
*this is just an example, you should be able to do this for any element in Groups 1, 2, 6 & 7.
What charge do the ions of elements in the following groups have?
a) Group 1
b) Group 2
c) Group 6
d) Group 7
a) Group 1: +
b) Group 2: 2+
c) Group 6: 2-
d) Group 7: -
Describe the structure and bonding of an ionic compound.
- Ionic bonding
- Giant structure of ions
- Lattice structure
- Oppositely charged ions held together by electrostatic forces acting in all directions
What type of bonding is represented by the diagrams below?
Ionic bonding
What are the limitations of the following diagrams to represent ionic structures?
- Dot and Cross
- Ball and Stick
- Dot and cross: Doesn’t show the structure of the ionic compound, the size or arrangement of ions.
- Ball and stick: Suggests gap between ions which aren’t in fact there.
Use the diagram to work out the empirical formula of the sodium chloride.
*this is just an example, you should be able to do this when given a diagram of any ionic compound.
By looking at the ratio of ions in the compound:
• Ratio of ions in compound 1:1
Or, to calculate using charges on ions
- Charge on sodium ion +
- Charge on chloride ion –
Answer: Formula of sodium chloride: NaCl
Small molecules contain what type of bonds?
Covalent bonds
What type of bonds exist in large molecules, such as polymers?
Covalent bonds
Give three examples of giant covalent structures.
- Diamond
- Graphite
- Silicon dioxide
What type of bonding is represented by the following diagrams?
Covalent bonding
What do the lines in the following molecule represent?
Single covalent bonds
Draw dot and cross diagrams for the following molecules:
a) Hydrogen chloride
b) Methane
*these are examples, you should be able to also do this for nitrogen, hydrogen, chlorine, oxygen, water and ammonia
What type of molecule is represented below?
Polymer
Describe the structure and bonding in a metal.
- Metallic bonding
- Strong metallic bonds
- Giant structure of metal atoms in regular pattern
- Outer shell electrons are delocalised
What type of bonding is represented by the diagram below?
Metallic bonding
Name the changes of state represented by the letters a,b,c & d below:
a) Melting
b) Freezing
c) Boiling
d) Condensing
Draw a particle model to represent the following states:
a) Solid
b) Liquid
c) Gas
What is the relationship between the forces between particles and a substance’s melting and boiling points?
The stronger the forces between particles, the higher the melting and boiling points (or vice versa)
What do the following state symbols represent?
a) s
b) l
c) g
d) aq
a) Solid
b) Liquid
c) Gas
d) Aqueous
Why do ionic compounds have high melting and boiling points?
Because a lot of energy is needed to break the many strong bonds.
Why do molten or aqueous solutions of ionic compounds conduct electricity?
Ions are free to move so charge can flow
Why do small molecules usually have relatively low melting and boiling points?
- They have weak forces between molecules (intermolecular forces)
- It is the intermolecular forces that are overcome, not the covalent bonds, when the substance boils.
What happens to the size of intermolecular forces as the size of molecules increase?
The size of intermolecular forces increase (hence higher melting and boiling points for larger molecules)
Can molecules conduct electricity? Give a reason for your answer.
No, because they have no overall electric charge.
What state are most polymers at room temperature? Why?
- Solid
- Because they are large molecules, with strong intermolecular forces, hence relatively high melting and boiling points (compared with small molecules).
What bonds must be overcome in order to melt or boil giant covalent structures?
The strong covalent bonds between the atoms
Name the structures represented by the diagrams below:
a) diamond
b) graphite
c) silicon dioxide (silica)
Diamond and graphite are made out of a single element. Name this element.
Carbon
Do metals have high or low melting points and boiling points?
High melting and boiling points
Describe how the arrangement of atoms makes pure metals soft.
- Atoms arranged in layers
- Layers slide easily over each other
Describe how the arrangement of atoms in an alloy makes alloys harder than pure metal.
- Different sized atoms
- Layers distorted
- Atoms can’t easily slide over each other
Why are metals good conductors of heat and electricity?
They have delocalised electrons that can carry the charge (in terms of conducting electricity) or transfer energy (in terms of conducting heat)
Describe the structure and bonding of Diamond.
- Giant Covalent Structure
- Each carbon forms four covalent bonds with other carbon atoms
Describe the properties of Diamond
- Hard
- Very high melting point
- Doesn’t conduct electricity
Describe the structure and bonding of Graphite.
- Giant covalent structure
- Each carbon forms three covalent bonds with other carbon atoms
- Forms layers of hexagonal rings
- No covalent bonds between layers
- One electron from each carbon atom is delocalised
Q. What is graphene?
Q. Name two uses of graphene.
- A single layer of graphite
- Used in electronics and composites
Q. What is the chemical formula of Buckminsterfullerene?
Q. What element are all fullerenes made from?
Q. Describe the structure of fullerenes.
- C60
- Carbon
- Mostly hexagonal rings of carbon (will also have rings with 5 or 7 carbon atoms). Can be spherical or cylindrical in shape.
What are cylindrical fullerenes called and why are they useful?
- Nanotubes
- They have a high length to diameter ratio making them useful for nanotechnology, electronics and materials.
Separate Q. Approximately what size are nanoparticles?
1-100 nm, or a few hundred atoms
Separate Q. Approximately what size are fine particles (PM2.5)?
100 to 2500 nm
(1 x 10-7 m to 2.5 x 10-6 m)
Separate Q. Approximately what size are coarse particles (PM10)?
2500 nm to 10000 nm
(2.5 x 10-6 m to 1 x 10-5 m
Separate Q. What type of particles are dust?
Coarse Particles
Separate Q. As the side of a cube decreases by a factor of 10, what happens to the surface area:volume ratio of the cube?
Increases by a factor of 10
Separate Q. Suggest some applications of nanoparticles.
- Medicine
- Electronics
- Cosmetics
- Sun creams
- Deodorants
- Catalysts
Separate Q. How does the surface area to volume ratio of a nanoparticle compare to a normal sized particle?
Nanoparticles have higher surface area to volume ratios (or vice versa).
Separate Q. What are some of the risks associated with using nanoparticles?
- Some people worried that nanoparticles will be in use before any effects on human health are fully understood.
- Though not confirmed, could cause cell damage, or damage to the environment if washed away.
