Click this button on your first visit to this page.
A link to the chemistry course for age 14-16 will appear here when enough of it has been written.
A link to the chemistry course for age 16-18 will appear here when enough of it has been written.
In the meantime, bits and pieces are available in the pages linked to from the following table, so you can explore them and get an idea of what's going to come later:-
Li Be B C N O F Ne
Na Mg Al Si P S Cl Ar
K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe
Cs Ba La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn
Fr Ra Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr Rf Db Sg Bh Hs Mt Ds Rg Cn
The atomic number is the number of protons in the atom, the electron arrangement helps you work out how many electrons are free to bond the atom to other atoms, and the mass is simply the number of protons plus the number of neutrons in the atom. Elements such as chlorine do not have half a neutron in each atom: most chlorine atoms have 18 neutrons while the remaining quarter have 20: the average (18.5) is added to the number of protons (17) to get the mass (35.5). The long, horizontal blue block of elements is often moved out of the main table so that it can be made narrower, so the red Sc, Y, La and Ac column then joins up with the main red block (starting with Ti, Zr, Hf and Rf).
For more accurate and extra details use this dynamic periodic table