Unit 1 The Science of Chemistry and Matter

What is Chemistry? Discuss with the person next to you different ways you think chemistry is present in your everyday life. Laboratory Energy Elements Compounds

Classification of matter Objectives: 1. Relate chemistry to everyday life. 2. Identify traditional areas of study in chemistry. 3. Define matter. 4. Categorize samples of matter as a mixture or a substance. 5. Distinguish between homogeneous and heterogeneous mixtures. 6. Describe ways components of a mixture can be separated 7. Explain the difference between a compound and an element.

Chemistry is the study of the composition of matter and the changes matter undergoes. Matter: anything that has mass and occupies space. There are five traditional areas of study for chemistry Organic chemistry: study of chemicals containing carbon. Inorganic chemistry: study of chemicals that do not contain carbon. Biochemistry: study of processes that take place in organisms. Analytical chemistry: focuses on composition of matter Physical chemistry: describes behaviors of chemistry.

Chemistry far and wide: Materials: plastic, glass, ceramics, perfumes, food, etc. Energy: fossil fuels, food, solar batteries, nuclear Medicine: penicillin, aspirin, Vitamin C Agriculture: fertilizer, pesticides, growth hormones Environment: ozone, carbon dioxide- global warming, pollution Astronomy: composition of planets and stars

Classification of matter Mixtures: a physical blend of two or more components. Ex. Salad, pizza, milkshake and air Heterogeneous mixtures: the composition is not uniform

Homogeneous mixtures: composition is uniform throughout. Also called solutions. In a solution we have a solute (substance being dissolved) and a solvent (substance dissolving solute) Water is the universal solvent Most are liquids Some are solids. Example alloys of different metals like brass, an alloy of copper and zinc. For tomorrow research what other types of alloys we use. Some are gases like the air

Figure 1.4a HOMOGENOUS MIXTURES HETROGENOUS

Pure Substances: have fixed composition. Elements are the simplest form of matter that has its unique set of properties. Ex. Gold is an element. All atoms of gold have the same properties. Elements are shown in the Periodic Table. There are more than 100 elements, most of them occur naturally. Elements are represented by one (a capital letter) or two letter symbols(a capital letter and a lowercase letter). Ex. C: carbonCo: cobalt Compounds is a substance that contains two or more elements chemically combined in a fixed proportion. Represented by chemical formulas using symbols of elements present in compound and subscripts indicated how many atoms of each element is present. Ex. H 2 O: water CO: carbon monoxide CO 2 : carbon dioxide

Learning Check: 1. How do elements relate to compounds? 2. How do elements and compounds relate to mixtures? 3. What is the main difference between pure substances and mixtures?

Learning Check: 1. How do elements relate to compounds? Compounds are made from elements chemically combined. 2. How do elements and compounds relate to mixtures? Elements and compounds physically combine to form a mixture. 3. What is the main difference between pure substances and mixtures? Pure substances have a fixed composition and the composition of mixtures may vary.

Classwork: p53 #1-3 HW: Bring tomorrow any sample of matter and share with the class how you would classify the sample and why.

Separation of mixtures Separate mixtures based on different physical properties of the components Centrifugation & Decanting Density EvaporationVolatility ChromatographyAdherence to a Surface FiltrationState of Matter (solid/liquid/gas) DistillationBoiling Point TechniqueDifferent Physical Property

DistillationFiltration

Breaking down compounds Methods used to separate mixtures can not be used to break compounds into simpler substances. To break down compounds, a chemical change has to occur which produces matter with a different composition than the original matter.

Changes in matter 1. Identify properties as extensive or intensive. 2. Define a physical property and a chemical property. 3. Describe a physical change. 4. Describe what happens during a chemical change. 5. Identify clues that a chemical change has taken place.

Changes in matter Physical change : same substance remains after the change. Ex. Pounding, cutting, dissolving Changes of state: melting, boiling, condensing, etc. Ex. Evaporating water from sea water to get salt.

Chemical change: a new substance appears after the change. New substance has different characteristics. (a chemical reaction) Evidence of chemical change Production of gas (observed as bubbles or change of odor) Release or absorption of energy (change in temperature or giving off light) A color change Formation of a precipitate (solid formed when two clear solutions combine and become cloudy) Ex. Burning, digestion, fermentation During a chemical reaction, the mass of products is equal to the mass of the reactants: law of conservation of mass.

Physical property: quality of a substance that can be observed or measured without changing the substance’s composition. Ex. Length, color, temperature Extensive: depend on the amount of matter present. Ex. Mass, length, volume Intensive: do not depend on the amount of matter present. Ex. Density, color, malleability (can be hammered), ductility (can be turned into wires), conductivity, melting point.

Chemical property : describes the behavior of a substance undergoing a chemical change. Describes how it reacts with other materials like air, water, and acids. Characteristics could be: acidity, flammability, reactivity, oxidizing ability, explosiveness. Ex. iron + oxygen  rust Indicating it does not react is also a chemical property.

Learning check: 1. Classify the following as a chemical or physical property a. Is red b. Reacts with water c. Boils at 88  C d. Dissolves in gasoline e. Is corrosive 2. Classify the following as a chemical or physical change a. Alcohol evaporating b. An explosion c. Digesting food d. Salt dissolving in water e. Grass growing

Learning check: 1. Classify the following as a chemical or physical property a. Is red physical b. Reacts with waterchemical c. Boils at 88  Cphysical d. Dissolves in gasolinephysical e. Is corrosivechemical 2. Classify the following as a chemical or physical change a. Alcohol evaporatingphysical b. An explosionchemical c. Digesting foodchemical d. Salt dissolving in water physical e. Grass growingchemical

Energy and change Energy is the capacity to do work. Always involved when there is a change in matter. Endothermic and exothermic processes Endothermic: energy is absorbed from the surroundings. (Ex. Boiling water) Exothermic: energy is released to the surroundings. (Ex. fire) Law of conservation of energy: during a physical or chemical change, the total quantity of energy remains the same. Energy can be released or absorbed as heat. Kinetic energy: energy of motion Temperature: measurement of average kinetic energy of the random motion of particles in a substance. Units: Celsius(  C), Kelvin (K) Zero in the Kelvin scale is called the absolute zero. K=  C + 273

Classwork: pg 62 #6-8

Unit 1 The Science of Chemistry and Matter