C HAPTER 1 Matter, Energy and Change

What is Chemistry? 1. Is a physical science: looks at nonliving things (rocks, stars, electricity) 2. Is the study of the composition, structure, and properties of substances and the changes they undergo

What is a chemical? 1. A substance produced by or used in a chemical process 2. A undesirable substance (pollution, poisonings) 3. A desirable substance (cure diseases, maintain food supply)

Branches of Chemistry 1. Organic chemistry: the study of substances containing carbon and hydrogen, and their derivatives 2. Inorganic chemistry: the study of all substances not classified as organic chemicals 3. Physical chemistry: the study of the properties, transformations and interrelationships of energy and matter

4. Biochemistry: the study of all substances and processes that occur in livings things 5. Analytical chemistry: the identification of substances and the qualitative and quantitative determination of the composition of materials

The Scientific Method 1. The goal is to solve a problem or answer a questions 2. The ultimate goal is to explain and predict natural phenomena 3. Is defined as a logical approach to the solution of problems that lend themselves to investigations by observing, generalizing, theorizing, and testing

Steps: 1. Observation All the information you can gather through the use of your five senses. 2. Question Sometimes the question come before observation.

3. Hypothesis Can never be a question, but a possible answer to the question which started the entire process. 4. Experiment Data is gathered, recorded, analyzed in order to insure an accurate conclusion.

5. Conclusion Are the results of experimentation and may raise new questions and lead to new hypothesis and new reasons for further experimentation. 6. Natural Law Describes HOW nature behaves.

7. Theory Explains why nature behaves in the way described by the natural law. Explains the original question and other questions that may have happened along the way. Also predicts the results of further experiments dealing with the question.

Matter and Energy 1. Matter: anything that has mass and takes up space So what does not have mass and takes up space? energy

2. Other definitions: a. Inertia: the resistance to change in motion b. Weight: the measure of the earth’s gravitational attraction for matter c. Mass: the measure of the quantity of matter

3. The Law of conservation of mass a. Matter cannot be created or destroyed in ordinary chemical or physical changes b. It simply changes shape or form

Definition of energy 1. The ability to cause change or the ability to do work 2. Two types a. Kinetic energy: energy in motion b. Potential energy: energy an object has because of its position or composition

Energy labels a. Chemical energy b. Mechanical energy c. Electrical energy d. Radiant energy

Law of Conservation of Energy “ Energy can not be created nor destroyed in ordinary chemical or physical means. It simply changes form.”

States of Matter 1. solid: definite shape and volume 2. liquid: definite volume, ability to flow and to take the shape of the container 3. gaseous: neither definite shape or volume 4. plasma: gaseous system composed of positively-charged particles and negatively-charged electrons

solidliquidgas plasma

Properties and Changes in Matter Properties: Characteristics that enables us to distinguish one kind of matter from another Physical properties: 1) Can be observed or measured without altering the identity of a material

2) Described as qualitatively (large, small, few, many) 3) Described as quantitatively ( 5 cm long, 20 pieces of Al) 4) Extensive: depends on amount of matter present (mass, length, volume) 5) Intensive: does not depend on amount of matter

(melting, freezing, boiling point, density, ductility, malleability, color, crystalline shape, refractive index) Physical change: A change in the property of matter that does not result in a change in identity. Ex. Cutting, smaching, change in state

change in state: g l s Chemical properties: Ability of a substance to undergo a change that alters its identity Ex. Burning, rusting, molding

Chemical change (chemical reaction) Any change in which one or more substances are converted into different substances with new identities reactants  products sodium + chloride  sodium chloride

Indications of chemical reactions 1. heat and light 2. production of a gas 3. formation of a precipitate precipitate: a solid that separates from a solution

Energy and changes in matter 1. Exothermic: a process that releases heat Ex. Water (l)  ice (s) + heat 2. Endothermic: a process that absorbs heat Ex. Ice (s) + heat  water (l)

Classification of matter 1. Mixtures A combination of two or more kinds of matter, each keep their own identities a. Heterogeneous mixture: the composition and properties are not uniform, they differ from one point to another

phases: same physical properties and chemical properties Ex. Ice and water (both H 2 O) b. Homogeneous mixtures: The composition and properties are uniform throughout the mixture

also called solutions can be separated What are the following mixture? 1. Sugar water 2. Vegetable soup 3. Brass 4. Granite 5. Notebook paper 6. Pencil lead

Pure Substances: A homogeneous sample of matter that has the same composition and properties, whatever the source. Ex. Water, sugar, oxygen, silver, graphite and lead

Pure substances differ from mixtures: 1. Every sample of a given pure substance has exactly the same characteristic properties. 2. Every sample of a given pure substance has exactly the same composition. 3. A pure substance cannot be separated into other substances without changing its identity and properties.

Pure substances continued: Elements and compounds Element: a pure substance that cannot be decomposed by ordinary chemical change ex. Calcium, oxygen, chlorine

Chemical compound: A pure substance that can be decomposed into two or more simpler substances by a chemical change. Ex. H 2 O, NaCl, HC 2 H 3 O 2

All matter  (Yes)  Can it be separated  (No) by physical means?  Mixtures Pure substance  (Yes) Is the composition (No) (yes) Can it be (No) uniform? decomposed by ordinary   chemical means?  Homogeneous Heterogeneous Compounds Elements