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High school students shares his learning of periodicity
  • High School
Lukas, Grade 11 DP HL Chemistry Student

Recently in Chemistry at the International School of Berne, we have been learning about periodicity within the Periodic Table of Elements. We have been focusing on the Alkali Metals and Halogens and the characteristics and trends associated with each.

Initially, we delved into the Alkali Metals, which are the elements found within Group 1 of the periodic table. Alkali metals are overall very unstable and highly reactive elements. Due to this, Alkali Metals are rarely seen as lone/native elements and commonly form ionic bonds with other non-metal elements. The most easily demonstrated trend seen within the Alkali Metals is the increase in reactivity as period number increases (as you go further down the table). This is due to the increase in the size of the atom. We observed this in class via a demonstration that involved the addition of the first three Alkali metals to water (H2O). Reactions ranged from skidding on the water's surface, self melting into a molten sphere, to creating a violet flame. We then observed the final Alkali metals through videos whereby full-blown explosions are observed!

Halogens are what we learned about next. Halogens are elements that are found within Group 17. Halogens are highly reactive elements (a similar property) to Alkali metals - one electron away from becoming stable, they must gain a single electron. Other characteristics of Halogens are they all have high electronegativities, with Fluorine having the highest. The common trend is that the reactivity of the Halogens decreases as you go down the group. This is due to an increase in atomic radius, causing less attraction between the nucleus and valence electrons, as well as increased core electronic shielding.

Finally, we looked at oxide trends across a period. Non-metals oxides form an acid, while on the other hand, metal oxides form a base. So, therefore, every oxide as you go across a period from left to right will decrease in acidity and ultimately form a basic substance. We also looked into interesting examples along the metalloid stepped boundary, such as Aluminum. Its oxide can behave in an amphoteric nature (both forming acid or base).

  • High School
  • STEM

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