Periodic Table

AS the fist topic in Lower Secondary Science, 2011, we studied on the periodic table. It was not a totally new concept to us as we touched on it last year. However, we got to study it deeper this year, giving us a better grasp on the topic. Here are some of the areas we learnt. (taken from the teacher's notes)


In the periodic table, the elements are arranged in order of increasing proton (atomic) number, and are classified according to Groups and Periods.
Group - a vertical set of elements
Period - a horizontal row of elements

The groups in the Periodic Table are numbered from I to VII and then Group 0. Some of these groups have names:

Group number Group
I Alkali metals
II Alkaline earth metals
VII Halogens
0 Noble gases

Elements between Group II and III are known as transition metals or transition elements.

Elements in the same group have similar chemical properties and will undergo the same type of chemical reactions.

Each period is numbered, 1, 2, 3, etc.

Elements in the 1st period will only have their 1st shell fully/partially occupied with electrons.

Elements in the 2nd period will have their 1st shell fully occupied with electrons, and their 2nd shell fully/partially occupied with electrons.

Down each group, the number of valence electrons is the same for each element and is equal to the group number.

Example: Group I Elements

Element Electronic configuration
Li 2.1
Na 2.8.1
K 2.8.8.1

Group I elements are very reactive. This similarity in reactivity is due to their electronic structure: one valence electron (advanced).

Generally, elements with small number of electrons in the valence shell (e.g. Group I and II) are metals. Elements with large number of electrons in the valence shell (e.g. Group VII and 0) are non-metals.

The line that divides metals from non-metals runs run diagonally through the Periodic Table. Elements found beside this dividing line are known as metalloids. Metalloids have some properties of non-metals and metals.

Charges on the ions formed are related to the group number and number of valence electrons.

Elements on the left side of the Periodic Table lose their valence electrons to form cations with charges corresponding to their group number. Elements on the right side of the Periodic Table gain electrons to form anions. The charges on the anions corresponding to the number of electrons gained to fill their valence shells with eight electrons.

I found that with all this infomation, I was able to answer the questions regarding the periodic table better than last year. The organisation of the notes is also very helpful and it makes revising for tests easier and more effecient