Notes

Elements
Imagine you are working as a lab technichian for the Break-It-Down Corporation. Your job is to break down incoming materials into the simpliest subtances you can obtain. One day material seems particulary difficult to break down. you start by crushing and grinding it. You notice that the resulting pieces are smaller, but they are still the same material. You try another physical changes,including melting,boiling, and filtering it, but the material does not change into anything simpler.
Next you try some chemical changes. For example, you pass electric current through the material. Although many subtances can be broken down using electric current, this material still does not become any simpler. After recording your observations, you analyze the results of your tests. you then draw a conclusion: The substance must be an element.

compounds
You learned in section that because most elements take apart in chemical changes fairly easily, few elements are found alone in nature. Instead, most elements are found combined with other elements as compounds.
A compound is a pure substance composed of two or more elements that are chemicaly combined. In a compound, a particle. In order for elements to combine, they must react or undergo a chemical change, with one another. The compound is a new pure substance that is different from the elements that reacted to form it.

Solubility: How Much Solute Can Dissolve? If you add too much sugar to a glass of lemonade, not all of the sugar can dissolve. Some of the sugar collects on the bottom on the glass. To determine the maximum amount of sugar that can dissolve, you would need to know the sollubility of sugar. the solubility of sugar. The solubility of a solute is the amount of a solute needed to make saturated solution using a given amount of solvent at a certain temperature. Sollubility is usually expressed in grams of solute per 100ml of solvent.