• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Evolution and development of the periodic table.

Extracts from this document...


Evolution and development of the periodic table: First efforts to classify elements came in the publication 'Trait� El�mentaire de Chimie' (Treatise on the Chemical Elements), published in 1789 by Antoine Lavoisier3. The 33 known Elements were separated as gases, metals, non-metals and earths. In the 19th century elemental discovery led to further efforts, with valency being a favoured sorting method. However, D�bereiner was first to sort elements by their weight/mass. He arranged elements to fit triads of similar properties, but also mass - each middle element had a weight equal to the average of the first and third. British chemist, Newlands, in 1863 formed the 'law of octaves' - every eighth element had similar properties. Newlands table, hindered by the noble gases remaining elusive - lacked organisation with elements sharing spaces, due also to inaccurate mass measurement1. The next major effort came from Dimitri Mendeleev helped by Stanislao Canizzaro, who, in 1958 clarified mass numbers for 65 known elements, allowing Mendeleev to arrange them into rows according to mass and columns of similar valency. ...read more.


Figure 2: (B) Gallium unusually forms multiple chlorides, which involve dative covalent bonds, rarely seen in metallic compounds (they are normally ionic). Also, Gallium's reactivity in both acids and alkalis is also characteristic of non-metals. This occurs as Gallium forms amphoteric hydroxides, which is a rare property1: 2Ga(s) + 6H+(aq) 2Ga3+(aq) + 3H2(g) 2Ga(s) + 2OH-(aq) + 6H2O(l) 2[Ga(OH)4]-(aq) + 3H2(g) Furthering our knowledge of atomic structure using spectroscopy and the UNILAC particle accelerator: In 1899, Ernest Rutherford proved the existence of sub-atomic particles when he proved a dense nucleus existed at the centre of atoms. He proved that this nucleus, in opposition to electrons, was dense and had a positive charge2. Chemists, such as Bohr, quickly capitalised on this discovery and in 1913, he published his theories regarding atomic spectra, refining Rutherford's idea of orbitals about a nucleus and proposing defined energy levels for electrons. Emission spectra are produced by exciting electrons with an electrical arc, then allowing electrons to drop to lower energy levels and emit additional energy in the form of photons. ...read more.


It is therefore believed that synthesising element 114 will contribute greatly to knowledge of the sub-atomic particles and their relation to isotopic/nuclear stability. From discovery to synthesis: Previously, chemists worked to discover elements as it was the most active area for chemical breakthroughs This was due to initiatives that allowed chemists to recognise properties, such as spectroscopy3. The likes of Mendeleev, in ordering the elements and predicting new ones, also promoted new discovery. Yet, recently, emphasis has been on the purpose of elements. Scientists have abandoned the discovery of natural materials and begun searching for synthesised alternatives. As elemental properties become more predictable, they become increasingly desirable and thus their synthesis more urgent. This was shown in the Cold War, where American and Russian scientists competed to produce more radioactive isotopes for use in weapons. Particle accelerators, such as the UNILAC have been pivotal in the formation of heavier elements and are seen as vital in achieving what is often referred to as 'the holy grail of elements' - element 114, which would lead to breakthroughs in knowledge about atomic structure and stability2. Such efforts to create new elements have labelled particle chemists: 'the new alchemists'(H). NAME: COWLIN, Robert CANDIDATE NUMBER: 8118 1 ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our GCSE Classifying Materials section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related GCSE Classifying Materials essays

  1. Marked by a teacher

    Chemistry revision notes. Atomic Structure and Bonding, Electrolysis, Acids and Alkalis.

    5 star(s)

    could be compared. Also, the rate of a reaction changes as it proceeds. When the reaction starts, the reactants are quite concentrated, but as it goes on, the reactants become less concentrated, and the reaction slows down and eventually stops. Energy changes in reactions (F) Reactions which give out energy are called Exothermic.

  2. Marked by a teacher

    Chemistry Revision Notes on atomic structure, nuclear power and the periodic table

    4 star(s)

    Although Bohr's model explained why electrons did not spiral in towards the nucleus, it did not explain all the known properties of atoms. > 1930: Schrodinger modified Bohr's model of the atom, viewing electrons as continuous clouds. > 1932: Sir James Chadwick discovered that the nucleus contained particles called neutrons, as well as positively charged protons.

  1. Peer reviewed

    Revision notes on elements, the periodic table and compounds.

    4 star(s)

    The zig-zag line divides the metals from non-metals - Metallic elements are arranged on the Right of the periodic table - Non-metalic elements are arranged on the Left of the periodic table SIMPLE FORMAT (of the first 20 elements) 1 H 2 He 3 Li 4 Be 5 B 6

  2. Peer reviewed

    The Sub-atomic particles

    4 star(s)

    This may make a big difference to the average mass of the atoms of the element and therefore to the relative atomic mass. Isotopes of carbon Carbon has three isotopes but the element consists mainly of carbone-12. The abundance gives the percentage of a given isotope in a sample of carbon.

  1. Free essay

    Periodic table

    - The valency of an element is equal to the number of electrons that atom needs to gain, lose or share to fill its outer shell. If electrons are lost the valency it + and if electrons are gained the valency is -.

  2. The Structure of the Atom.

    at 66. peak with a mass to charge ration of 78, with a smaller peak (one third of the size) at 80. Therefore chloropropane would have a large molecularion Brominated Organic molecules. Bromoalkanes can also often be identified by the shape of their molecularion peaks.

  1. Classify and identify different polymers to determine their physical properties and uses.

    Put 3 drops of hydrochloric acid 0.1M on each polymer. If the acid touches your skin, wash it off immediately. 3. Let the polymers sit for 2-3 minutes to see the result. 4. Record the results. Once the testing is complete is it important to wash the heatproof mat to ensure that all traces of acid have been erased.

  2. A practical study of the periodic table.

    + H2O(l) � Mg2+(aq) + Cl-(aq) Calcium chloride, which is strongly hygroscopic, reacts with water to produce hydrated calcium chloride. CaCl2 + 2 H2O � CaCl2�2H2O Aluminium chloride partially hydrolyses with H2O. Aqueous solutions of AlCl3 are fully ionized, that is why they conduct electricity well.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work