[S2 Maths + Science PMCians]
What we did in 2 hours:
This week we carried on with our Part 2 of Chemistry Headstart on Chemical Equations.
First we had a quick recap on how to determine the charge of ions based on their group number in the Periodic table. Then we move on to learn how to write the chemical formula and name of ionic and covalent compounds.
– charges of ions must balance in a chemical formula
– name of non-metal negative ions end with -ide
– name of polyatomic ions which carry oxygen end with -ate
– prefixes (e.g. mono, di, tri) are used to indicate the number of a given element present in covalent compounds
Next, we learnt about equation writing, which include balancing and writing the state symbols.
-Strategies for balancing chemical equations
1) calculation by atoms
2) calculation by ions
3) transfer of oxygen
4) balance everything before hydrogen/oxygen
5) fractions
– Solubility table (need this to determine the state symbol)
1) ALL group I, ammonium and nitrates are soluble in water
2) MOST sulfates and chlorides are soluble in water, except barium, lead & calcium sulfates and silver & lead chlorides
3) MOST carbonates and hydroxides are insoluble in water, except group I & ammonium carbonates and group I & some group II hydroxides
Finally, we learnt about acid/alkali reactions and practised to write balanced chemical equations with state symbols of these reactions.
Special Mention:
Next lesson, which is the last lesson of our headstart, we will be doing Physics Headstart on Lens.
See you soon! 🙂
Your friendly tutors,
The S2MA+SCI Team
