Balanced chemical equation

On the 14th December, me and Samnang Hor taught a junior STEM class about balancing chemical equation. So we come up with some fun activities for them to practice like using the simulation and also Kahoot. We start off by trying to understand what they have learned than explain them why do we need to balanced chemical equation. We need to balance the chemical equation because the mass of the atom can’t be created nor destroyed according to the law of conservation of mass.

+  The plus symbol connects the first substances and the final substance. (seperate two reactants or products)

→  Identify the chemical reactions into products. Or chemical change or produce.

Reactants are the starting materials in chemical reaction. The substance that go through changes during the reaction. The substances on the left side of the arrow are called reactants.

The substances on the right side of the arrow are called products.

Can’t write # 1 as the coefficients but just put a blank there. Example: O2
Balancing chemical equation

Link to the presentation :

Chemistry round 2

We been learning and using the periodic table for awhile now. There are many topics in chemistry we been covered. This round we focus more on drawing lewis dot structure that related to elements, atoms, compounds. Than we learn about the octet rules and formal charge. Element that are on or under the 3rd row in periodic Table can hold up to 10 electrons breaking the octet rules.

Lewis dot structure → shows bonding between atoms


Li ⇒  is Lithium and it have 1 electrons

Octet rules atom wants to have eight valence electrons in its outermost electron shell to become like a noble gas so, it combine with other atom and share electrons.


H2O ⇒ is an chemical formula stand for water

H: 1 electrons & O: 6 electrons = 8 electrons

*This sign    stand for 2 electrons*

Formal charge ⇒ the charge that are assigned to an atom, assuming that electrons in bonds are shared equally between atoms.

Equatione: (# valence electrons) – (# valence electrons in bonded atom) = 0


H = 1 e        1 – 1 = 0 *True*

O = 6 e        6 – 6 = 0 *True*

*Because it share electrons that why we count only 1 of the electrons that they are holding to.*

Density of the coin

Last year in science class we learned about physic and this year we are learning about chemistry. I don’t like the chemistry but now I feel it’s just like physic so I can relate too a lot. First off we need to draw the classroom in order for us to be safety and know where everything is place. In Order to be safety, when we are doing a lab we need to have safety glasses, lab coat and sneaker to cover up your feet. After learning for a week start with a lap which is about the density of the coin. It was a pretty good experiment because we get to do it individually and there are variety of coins that we can choice from. For our lab notebook in there we need to write our own hypothesis, procedure, data, analysis and conclusion.