C3 - Structure and Bonding Flashcards
Where do ionic bonds form?
- Compounds formed from metals + non-metals
- Oppositely charged ions
What is ionic bonding?
- Metal donates electrons to a non-metal
- Metal loses electrons to form positive ion
- Non metal gains electrons to form negative ion and full outer shell
What is an ionic compound?
- Giant structure of ions
- Held together by strong electrostatic forces of attraction between oppositely charged ions
Describe the structure of a crystal of sodium chloride, 3 POINTS
- Giant ionic lattice
- The positive sodium and negative chlorine ions form a closely packed regular arrangement
- Very strong electrostatic forces of attraction between the oppositely charged ions
What are the main properties of ionic compounds?
- High melting + boiling points - strong bonds between molecules
- No electricity conducted when solid - ions not able to move freely in fixed position
- Conduct electricity when molten/dissolved - ions free + able to move
What is an ion?
- Number of protons different from number of electrons
What is the ion for group 1?
+1
What is the ion for group 2?
+2
What is the ion for group 3?
+3
What is the ion for group 5?
3-
What is the ion for group 6?
2-
What is the ion for group 7?
1-
What is the ion for hydroxide?
OH-
What is the ion for sulfate?
SO4(-2)
What is the ion for nitrate?
NO3(1-)
What is the ion for carbonate?
CO3(2-)
What is the ion for ammonium?
NH4(+1)
Where do covalent bonds form?
- In most non-metallic elements
- In compounds of non-metals
What is covalent bonding?
- Electrons are shared between non-metal atoms
- Number of electrons depends on how many electrons an atom need to make full outer shell
What are the 2 properites of small covalent molecules?
- Low melting + boiling points - weak bonds between molecules so little energy needed
- Poor conductors - no delocalised electrons/ions to carry charge
What are giant covalent structures?
- Many billions of atoms, each with a strong covalent bond
What are the properties and structure of diamond? (3)
- Each carbon atom covalently bonded to 4 others
- High melting + boiling points - strong covalent bonds between atoms which take lots of energy to overcome
What is the structure and properties of graphite?(4)
- Giant covalent structure
- Each carbon atom bonded to 3 others in hexagonal rings in layers
- High melting + boiling points - strong bonds
- Can conduct electricity - free electrons
What are the properties and structure of graphene?
- Single layer of graphite
- Conducts electricty
- Very strong
- Used in high tech
What are fullerenes?
- Molecules of carbon atoms with hollow shapes
What is the structure and uses of buckminsterfullerene? (4)
- 60 carbon atoms
- Weak, intermolecular forces
- Can slide over each other
- Used for lubricants or drug delivery
What is metallic bonding?
- The electrons in the outer shell of metal atoms are delocalised and so are free to move through the whole structure
- The sharing of delocalised electrons
Explain the properties of carbon nanotubes? (3)
- High tensile strength
- High melting point as each atom is joined covalently to 3 others
- Sea of delocalised electrons, free to move - electricity conducted
What are the problems with the simple particle model? (3)
- No forces shown
- Assumes they are all spheres
- Assumes they are all solid
How are atoms arranged in pure metals?
- atoms are arranged in layers, which allows metals to be bent and shaped
How and why are alloys made?
- Mix multiple pure metals as they are too soft for many uses
- Alloys are harder
Why are alloys harder than pure metals?
- Alloys contain atoms of different sizes, which distort the regular arrangements of atoms
- Harder to slide over each other
What is nanoscience?
The study of structures that are between 1 and 100 nanometres (nm) in size
Why are properties of nanoparticulate materials different to same material in bulk?
- the tiny size of nanoparticles compared to the same material in bulk
- the large surface area to volume ratios of nanoparticulate materials compared to the same material in bulk
What are the uses of nanoparticles?
- Suncream, deodorant
- Electronics
- Catalysts
What are two risks of nanoparticles?
- Could catalyse harmful reactions in the body
- Organ damage
