C1 Atomic Structures

C1 Atomic Structures

1. C1.8 Electronic Structures

   • Electrons orbit the nucleus in shells
   • Electron Shell Diagrams
     • the first shell can hold 2 electrons, the rest can hold 8. / the 'electronic structure' is the shorthand, you just write the number of electrons in each shell (e.g. 2,8,1 for Sodium)

2. C1.7 Ions, Atoms and Isotopes

   • Isotopes
     • Atoms of the same element always have the same number of protons, neutrons can change between atoms of the same element. these are isotopes. / isotopes have the same atomic number, but different mass number. / the extra neutrons will sometimes make the isotope unstable, radioactive. / different isotopes can have different physical properties, some may be denser or radioactive.
   • The Size of Atoms
     • 7000000000000000000000000000, the number of atoms in the average human body. / however, they can't be seen. each atom is about a billionth of a metre across.
   • Representing the Atomic Number and Mass Number
     • 12       Mass Number     C     6         Atomic Number / protons = atomic number = 6 electrons = atomic number = 6 neutrons = mass number - atomic number = 6
   • What is an Ion
     • an ion is an atom with extra electrons /an ion is negatively charged as the electrons outnumber the protons.

3. C1.6 Structure of the Atom

   • Atom: Nucleus, Electrons Nucleus: Protons, Neutrons / mass: proton = 1 = neutron electron = 0 / charge: proton = 1 neutron = 0 electron = -1
   • Mass Number
     • the number of protons and neutrons are the mass number
   • Atomic Number
     • the number of protons in an atom is the atomic number, this is equal to the number of electrons. / this is what the elements are ordered in.

4. C1.5 History of the Atom

   • Evidence for Neutrons in the Nucleus
     • 1932, James Chadwick carries out an experiment that proves the existence of neutrons. / scientists had speculated that there was a second sub-atomic particle in the nucleus of atoms, to explain the missing mass from the protons.
   • Evidence for Electrons in Shells
     • 1914, Niels Bohr revised the atomic model again. / he did this through the light given off when atoms were heated, it was given in levels, so he suggested that the electrons are in levels (shells) to match this.
   • Evidence for the Nucleus
     • 10 years after the electron discovery, Gieger and Marsden were doing and experiment with radioactive particles. / the results suggested a different model for the atom.
   • Evidence for Electrons in Atoms
     • at the end of the 1800's, a scientist (J.J. Thomson) discovered the electron. A tiny negatively charged particle with a mass 2000x smaller than the lightest atom.
   • Early Ideas about Atoms
     • The ancient Greeks were the first to have the idea of atoms and particles, however, it wasn't til the early 1800's that these ideas became linked. / reactions suggested that atoms re-arranged themselves and combined with other atoms in new ways.

5. C1.4 Fractional Distillation and Paper Chromatography

   • paper chromatography
     • used to identify substances from mixtures in a solution. / utilises their attraction to the paper and solvent
   • Fractional Distillation
     • the same as distillation, but for separating a mixture of liquids. / E.G. Crude Oil /

6. C1.3 Separating Mixtures

   • a mixture is made up of two or more substances that are not chemically joined. / mixtures need to be separated to be analysed.
   • Distillation
     • used to collect a solvent, such as water, from a mixture. / this is done by evaporating the solvent and putting it through a condenser.
   • crystallisation
     • used to separate a soluble in a solvent, such as salt and water. / this is done by evaporating away the solvent, leaving the soluble behind. 
   • Filtration
     • used to separate an insoluble in a particular solvent, such as a mixture of sand, salt and water.

7. C1.2 Chemical Equations

   • chemical equations show the reactants(starting substances) and the products(ending substances) / word equation for hydrogen gas test: Hydrogen + Oxygen -> Water. / Symbol equation,always balanced(same amount on each side), for carbonate decomposition: CaCO3 -> CaO + CO2 / Law of conservation of mass: the total mass of the products formed in a reaction is equal to the total mass of the reactants.
   • Making an equation balance
     • H2 + O2 -> H2O reactants: 2 H, 2 O products: 2H, 1 O / H2 + O2 -> 2H2O reactants: 2 H, 2 O products: 4 H, 2 O / 2H2 + O2 -> 2H2O reactants: 4 H, 2 O products: 4 H, 2 O
   • Adding State Symbols
     • state symbols can be added to a balanced symbol equation to put in extra information. / (s) for solids, (l) for liquids, (g) for gases and (aq) for aqueous solutions: CaCO3(s) -> CaO(s) + CO2(g)

8. C1.1 Atoms

   • All substances made of atoms. / a group of the same atoms is an element. / elements can have very different properties.
   • Atoms, Elements and Compounds
     • compounds are mixtures of elements bonded together. / E.G. H2O=2Hydrogens, 1Oxygen / some compounds are just two different types atoms, others can be more. / All atoms are made up of a tiny central nucleus with electrons orbiting around.
   • Chemical Symbols
     • Chemical Symbols are important as they allow for all nationalities to understand which element people are talking about. / E.G. O=Oxygen, Na=Sodium / arranged in columns, groups, and rows, periods, on the periodic table.