Lesson 3, 4 and 5

In lesson 3, we covered a lot! Starting with physical change and chemical change. During a physical change, it is a change in matter in which a substance changes form but not identity. And a chemical Change is a change in matter that results in the formation of a new substance(s) with new properties. It is not always possible to distinguish between physical and chemical change based on observations alone. Ionic compounds do not dissolve in the same way as molecular solids. Something important to know is an ionic equation. Dissolving is considered a physical change (generally).

It looks like this: Ca2+ (aq) + Cl- (aq).

In lesson 4, if a gas is one of your products, the mass of the product will be less than the mass of then the reactants UNLESS you trap the gas! That's important to know! Also, on the entire planet there is essentially an unchanging number of atoms. With this, it is crucial to know matter cannot be created nor destroyed!! And mass and weight are DIFFERENT. Mass is the amount of "stuff" and weight is the gravitational pull. Individual atoms are conserved in chemical reactions and physical changes: the number of atoms of each element remains the same from start to finish!

In lesson 5, a balanced chemical equation is one that shows the true mathematical relationship between the reactants and the products in a chemical reaction. When balancing equations, start with atoms that only show up once on each side of the equation. Important! When balancing equations, you can only change the coefficients! That sums them up! Homework below :)

Homework:

This is for you Mrs.McDowell: :) sooo cute!

 

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