When things are melted or boiled the bonds between them need to be overcome Strength of bond leads to boiling/melting temp. High temp = strong bond Stronger bond in metals, than non-metals
Atomic Size? Determined by the space the e- take up Think about what you know – predict what happens left to right....... Atomic size decreases across table because e- fill in existing shell & 1 more P+ thus hold in closer
Ionisation enthalpy is the amount of energy needed to remove e-’s from atom First ionisation enthalpy = 1 st outermost e- to be removed Increases enthalpy across a period - why do you think this happens?
Trends Look at what is different – down a gp shell of e- Across a period – the atomic number (P+ ) and thus e- 3 main factors you need to consider – charge of nucleus – Amount of shielding by inner e- – Distance between outer e- & nucleus
Mendeleev Prediction When Mendeleev constructed his periodic table he left gaps in it for new elements & predicted the PROPERTIES that element would have. Germanium (Mendeleev called it eka-silicon) Predicted appearance, RAM, density, reaction with water/acid/alkali/oxide & chloride
Who am I A’s write an element down and now describe it to your partner in terms of density, mp/bp, atomic radi, oxide & chloride formed – see if they get it right Description graphs p238/239/240 Chemical Ideas Swap over
Exam Question Tips Many times exam papers will ask you about an element that you have not covered – this is so you can apply your knowledge of the rest of the group/period to that case Key skills is to learn to read the various graphs Justify your answer – why will the melting point decrease?
Write a summary of periodicity, periodic patterns including these keywords Electron arrangement Melting points/boiling points Trends Density Ionisation enthalpies Atomic size