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- Observing Chemical Change. Properties and Changes in Matter. Matter can undergo both physical change and chemical change. - Observing Chemical Change. Properties and Changes in Matter. Chemical changes occur when bonds break and new bonds form. - Describing Chemical Reactions.
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- Observing Chemical Change Properties and Changes in Matter • Matter can undergo both physical change and chemical change.
- Observing Chemical Change Properties and Changes in Matter • Chemical changes occur when bonds break and new bonds form.
- Describing Chemical Reactions Describing Chemical Reactions • Cellular phone messages make use of symbols and abbreviations to express ideas in shorter form. Similarly, chemists often use chemical equations in place of words.
- Describing Chemical Reactions What Are Chemical Equations? • A short, easy way to show a chemical reaction. • Chemical equations use chemical formulas and other symbols instead of words to summarize a reaction.
- Describing Chemical Reactions Chemical Formulas • The formula of a compound identifies the elements in the compound and the ratios in which their atoms are present.
- Describing Chemical Reactions Conservation of Mass • The principle of conservation of mass states that in a chemical reaction, the total mass of the reactants must equal the total mass of the products.
Open System vs. Closed System Open System- A system that allows matter to enter from or escape to the surroundings. Closed System- A system that does not allow for matter to enter from or escape to the surroundings. A chemical reaction taking place inside of a plastic, sealed bag.
- Describing Chemical Reactions Balancing Chemical Equations • To describe a reaction accurately, a chemical equation must show the same number of each type of atom on both sides of the equation.
- Describing Chemical Reactions Balancing Chemical Equations • Magnesium metal (Mg) reacts with oxygen gas (O2), forming magnesium oxide (MgO). To write a balanced equation for this reaction, first write the equation using the formulas of the reactants and products, then count the number of atoms of each element.
Balancing Chemical Equations: Balance the equation for the reaction of sodium metal (Na) with oxygen gas (O2), forming sodium oxide (Na2O). - Describing Chemical Reactions Balancing Chemical Equations
Balancing Chemical Equations: Balance the equation for the reaction of tin (Sn) with chlorine gas (Cl2), forming tin chloride (SnCl2). - Describing Chemical Reactions Balancing Chemical Equations
- Describing Chemical Reactions Classifying Chemical Reactions • Many chemical reactions can be classified in one of three categories: synthesis, decomposition, or replacement.
Graphic Organizer Chemical reactions can be are written as Endothermic reactions Exothermic reactions Equations balanced with which require written using Coefficients Activation energy Chemical symbols Arrows and plus signs