C2 - Elements, compounds and mixtures Flashcards
What is in the periodic table?
Group number: columns + the number of electrons in the outer most shell
Period number: Rows + the number of shells the atom has
Left = metals
Right = Non metal
Group 0 = Noble gases (outer shells are full)
What is the electron distributions?
1st shell - 2 electrons
2nd shell - 8 electrons
3rd shell - 8 electrons
What is the Relative atomic mass (R.A.M)?
The relative abundance –> To find out how much of an element there is from its isotopes.
(percentage / 100 x mass number) + (percentage / 100 x mass number)
Eg: Chlorine has two naturally forming isotopes (Cl-35 and Cl-37). 75% of the chlorine atoms are Cl-35. Find the relative atomic mass of chlorine?
(75/100 x 35) + (25/100 x 37) = 35.5
What is Relative formula mass (R.F.M)?
Relative formula mass is all the mass numbers of the compound’s elements added up.
Eg: What is the Relative formula mass of H2SO4? H = 1 S = 32 0 = 16 (1 x 2) + 32 + (16 x 4) = 98
What is ionic bonding?
Ionic bonding is bonding between a metal and a non metal.
Metals lose electrons to form positive ions and non metals gain electrons to form negative ions.
Ionic compounds
They have a giant ionic lattice structure
PROPERTIES:
- High melting and boiling point : lots of energy is required to break the strong electrostatic forces of attraction between oppositely charged ions.
- They don’t conduct electricity in the solid state but they do in the liquid state: in the solid state the ions are restricted in the giant ionic lattice and cannot conduct electricity. In the liquid state the ions are mobile are can conduct electricity.
Simple covalent molecules
This has bonding with two non metal elements and bond by sharing electrons.
PROPERTIES
- Low melting and boiling points: Although there are strong covalent bonds between the non metals, there is weak intermolecular bonds between molecules which can break easily at low temperatures.
- Don’t conduct electricity as there are no delocalised electrons
Diamond:
Hard and lustrous
- -> Doesn’t conduct electricity as each carbon atom bonds to 4 other carbon atoms leaving no delocalised electrons
- -> High melting and boiling points as a lot of energy is required to break the strong covalent bonds
Graphite and graphene:
Slippery and conducts electricity
–> Slippery: Weak intermolecular bonds between layers allow layers to slip over each other
–> conducts electricity as each carbon atom bonds to 3 other carbon atoms leaving one delocalised electron per carbon atom.
Graphene is one layer of graphite
What are fullerenes?
Covalent structure
- shaped like a hollow ball
- Conducts electricity as each carbon atom bonds to 3 other carbon atoms leaving one mobile electron per carbon atom.
What is a nanoparticle? + uses
- It is between 1 -100 nanometers
- Has high surface area to volume ratio
Lubricants
Sun creams
deodorants
What is metallic bonding?
- Positive metal cations within a sea of delocalised electrons
Properties of metals:
1) Malleable - they have layers of cations which can slide over each other.
2) Conducts electricity - sea of delocalised electrons can conduct
3) high melting/boiling points as lots of energy is required to break the strong electrostatic force of attraction between metal ions and delocalised electrons.
Structures and melting/ boiling points:
Simple covalent bonding - low melting/ boiling points. Although they have strong covalent bonds the intermolecular bonds are weak and break easily
Giant covalent structures: High melting and boiling points as high amounts of energy required to break strong covalent bonds.
Ionic lattice structure: High melting / boiling points as large amounts of energy required to break strong forces of attraction between positive and negative ions.
Metallic: High melting and boiling points as high amounts of energy required to break electrostatic forces of attraction between metal cations and sea of delocalised electrons.
What is a pure and impure substance?
Pure: contains one element or molecule
Impure: Contains more than one element or molecule
