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

Atomic Structure Notes

Extracts from this document...


Atomic Structure Notes Atoms Atoms are tiny particles which make up matter. They contain a nucleus which is surrounded by electrons. The nucleus itself contains smaller particles called protons and neutrons. The nucleus, and protons and neutrons, are much more massive than electrons. Protons and electrons have a very small electrical charge. Protons are positively charged; electrons are negatively charged. Relative Mass Relative Charge Proton 1 +1 Neutron 1 0 Electron 1/1840 -1 Atoms of a certain element all have the same number of protons and electrons, e.g. all atoms of lithium have 3 protons and 3 electrons. Ions Atoms can gain or lose electrons so that they have unequal numbers of protons and electrons. These new particles are called ions. They are indicated by a charge. e.g 27Al3+ this ion has lost 3 electrons. 13 18O2- this ion has gained 2 electrons. 8 Isotopes The number of neutrons can vary. Isotopes are atoms of the same element with different numbers of neutrons and different mass numbers. e.g. chlorine, carbon, hydrogen Isotopes of an element have identical chemical properties, but they can have different physical properties. Isotopes of the same element with more neutrons have: * higher density * higher melting and boiling points * slower rate of diffusion Many isotopes are radioactive; these are called radioisotopes (radioactive isotopes) ...read more.


As electrons are successively removed, there is less shielding: the ionisation energy increases because the effective attraction to the positive nucleus is greater. c. Size of positive charge Removing an electron from a positive ion is more difficult than removing an electron from a neutral atom. The greater the positive charge on an ion, the harder it is to remove an electron, so the successive ionisation energies increase. Prediction of electron structure from ionisation energies The subsequent ionisation energies of an element can be used to confirm the electron configuration of the principal quantum shells. e.g. for sodium No of electrons removed ?Hi1 (kJ mol-1) Log10?Hi1 1 510 2.70 2 4560 3.65 3 6940 3.84 4 9540 3.97 5 13400 4.13 6 16600 4.22 7 20100 4.30 8 25500 4.40 9 28900 4.46 10 141000 5.14 11 158700 5.20 A graph of ionisation energy against log10?Hi will show a jump when an electrons start to be removed from a lower principal quantum shell. Electromagnetic waves Ocean waves travel on the surface of the water. You can see them and you can feel them. As you swim through the water, you can even make your own waves. The wind creates waves in the flag. Both the waves in the flag and the ocean waves are waves that you can see. ...read more.


At low absorbed energies, electrons may be excited to a higher energy level, then fall back to a lower energy level. At higher absorbed energies, bonding electrons separate. Covalent bonds break by homolytic fission and free radicals are formed. For example: Cl2 � *Cl + *Cl At very high absorbed energies, electrons can leave a molecule causing it to be ionised. For example: Cl2 � Cl + e- First Ionisation Energies of Successive Elements The first ionisation energy generally increases across a period because the nuclear charge increases, so the electrons are held more tightly, and more energy is needed to remove them. Nuclear charge also increases across a period, which pulls the electrons closer, decreasing the atomic radius. This also causes first ionisation energy to increase, because the attraction between the positive nucleus and negative electrons is greater when they are closer. There is a decrease between group 2 and group 3 elements. The electrons in the p sub-shell are at a higher energy level than those in the s sub-shell so are more easily removed. There is a decrease in first ionisation energy between groups 5 and 6. In group 6, there are two electrons in the same orbital of a p sub-shell. It is easier to remove one of them because the other electron in the orbital repels it. First ionisation energy decreases down a group, because there are successively more principal energy levels (shells) so electrons are further away from the nucleus, more shielded, and therefore less energy is needed to remove them ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our International Baccalaureate Chemistry 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 International Baccalaureate Chemistry essays

  1. Research question - How many molecules are there in a liquid drop?

    and we can see by the graph that the number of molecules it has is relatively lower than that of water's however the mass of the drop is higher than that of water's. This shows that glycerine molecules are heavier than water molecules.

  2. IB chemistry revision notes

    * Much of the atom is empty space * Electrons and protons are deflected by and electric field. Neutrons aren't. Atomic Numbers * It is the number of protons in the nucleus of an atom. * Defines which element the atom belongs to and consequently its position in the Periodic Table.

  1. IB questions and answers on Atomic Theory

    # of electrons 26 31 26 12 12 10 6 8 6 6 6 6 92 143 92 17 18 18 7. Fill in the chart: Atomic # Symbol # protons Mass # # neutrons Charge 3 electrons 33 As 33 75 42 -3 36 64 Gd 64 155 91

  2. In our research project, we will try to compare the qualitative contents of some ...

    as we wanted to compare the element of flavor on the drink's chemical components. As a result, we would get a much better insight into the uses of such chemicals. Picture Taken From: http://www.vitazone.com/assets/images/inner/var_orange.jpg Vita Zone (Orange) Electrolyte Test Chloride Test Test for Reducing Sugars pH Test Result Positive Positive Positive Acidic Remarks The solution contains electricity.

  1. Determining the position of unknown element X in the Reactivity Series

    This is because Copper is further below Lead in the reactivity series. Thus a reaction between Zinc and a Copper compound will be more reactive (& will have a higher ?H) than a reaction between Zinc and Lead. When ?E (?Energy)

  2. Practical de quimica Structure and Bonding

    Solutes with Hexane Substance Observations Calcium Chloride No dissolution, Calcium chloride ended at the bottom of the test tube. Graphite No dissolution, graphite ended at the bottom of the test tube. Iodine Dissolved very quickly, at the end a homogeneous purple substance was formed.

  1. Experiment to find the relative atomic mass of lithium

    This is because of a slow reaction time and the fact that the bung didn?t fit through the opening of the flask at the exact moment. A less amount of hydrogen gas was collected therefore decreasing the number of hydrogen molecules and therefore a less number of lithium molecules which

  2. Determining the relative atomic mass of Lithium

    the Ar of a reactant by measuring the volume of gas produced, as long as we have recoded the temperature and pressure. The final experimental result was that the relative atomic mass of Lithium is 7.2 The percentage error of my experiment is calculated though the following formula.

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