Chemical reactivity The full version will be presented Mon 31 st July 2006 See you at the EXPO!

Last week our focus was; 1.Elements and compound 2. The work and thinking of the scientists who developed the periodic table (Hennig Brand, Johann Dobereiner, John Newlands and Dimitri Mendeleev ) The physical properties of both metals and non metals (Groups, periods, atomic and mass numbers) 5. The reactivity of some elements 3 4

This week please think about the following; 1. the structure of the first 20 elements 2. The special stability of the inert gases 3. Why the other elements take part in chemical reactions 4. Ionic and covalent bonding 5. Learn the symbols/charges for some common ions.

Gp 1 Gp 2 Gp 3 Gp 4 Gp 5 Gp 6 Gp 7 Gp Essential Info

Useful links Who was Dmitri Mendeleev? Who was Dmitri Mendeleev? A Quick look at the History of the Periodic Table A Quick look at the History of the Periodic Table Periodic Table.com Periodic Table.com Dimensional Periodic Table 2 Dimensional Periodic Table Dimensional Periodic Table 3 Dimensional Periodic Table The Development of the Periodic Table The Development of the Periodic Table Web Elements Web Elements Chemical Elements.com Chemical Elements.com Periodic Table of Elements Periodic Table of Elements Period Table.com for Students Period Table.com for Students

The basic stucture of the atom NUCLEUS Electrons in orbits The nucleus contains protons and neutrons The electrons spin around the nucleus in orbits Essential Info

The electrons are found in orbits which spin around the nucleus Generally as the orbits get further from the nucleus their size gets larger. They hold more electrons!

Atomic number = number of protons and number of electrons Atomic Mass = number of protons and neutrons added together Number of neutrons = Mass number - atomic number Essential Info Na 11 23

Some atom structures I discussed atomic structure at this point

Na 23 11

Fluorine F 19 9 Cl F

Potassium K K 39 19

You should be able to draw diagrams for the first twenty elements!!!!

Turn to page 497 and find out why atoms take part in chemical reactions The p497 was mentioned in a Harry Potter film It does not refer to any school text

Why do chemical reactions take place? The inert gases are completely stable and DO NOT take part in chemical reactions Atoms of other elements take part in chemical reactions so that they can become more stable. They would all like to have the same electron arrangements as the inert gases. They can do this by either transferring electrons completely or by sharing electrons

Why does Mg react with O? Mg is a group 2 metal. Its outer orbit has 2 electrons It would like to become more like Ne. Ne is stable and has a full outer orbit. O is a group 6 non metal. Its outer orbit has 6 electrons. It would also like a full outer orbit By reacting together they can achieve this!

Mg O

Student guide to writing chemical formulae ;

Rules leading to correct formula Please copy into your exercise books 1. Positive ions (cations) can join to negative ions (anions) 2. Positive ions usually form the first part of the name (99% cases) 3. If the formula is correct there is no overall charge 4. If you have more than one polyatomic ion it is placed inside brackets

Essential training ions Positive ions Negative ions sodium Na+ potassium K+ hydrogen H+ lithium Li silver Ag+ fluoride F- chloride Cl- bromide Br- hydroxide OH- nitrate NO3- hydrogencarbonate HCO3- magnesium Mg2+ calcium Ca2+ barium Ba2+ zinc Zn2+ iron(11) Fe2+ copper Cu2+ carbonate CO3 oxide O2- sulphide S2- sulphate SO4 sulphite SO3 chromate CrO4 aluminium Al3+ chromium Cr3+ iron(111) Fe3+ nitride N3- phosphate PO4 ammonium NH4+

IONS TABLE

Chemical Formulae 1. CHARGES IONS NUMBERS FORMULA sodium fluoride

Chemical Formulae 2. CHARGES IONS NUMBERS FORMULA magnesium fluoride

Chemical Formulae 3. CHARGES IONS NUMBERS FORMULA silver hydroxide