Transcript Unit 1 science of chemistry
Unit 1 The Science of Chemistry and Matter
What is Chemistry?
Energy Elements Laboratory Compounds POD: Discuss with the person next to you different ways you think chemistry is present in your everyday life and write it down on your pod.
Classification of matter
Objectives: 1.
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Relate chemistry to everyday life.
Identify traditional areas of study in chemistry.
Define matter.
Categorize samples of matter as a mixture or a substance.
Distinguish between homogeneous and heterogeneous mixtures.
Describe ways components of a mixture can be separated 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
MIXTURES
HOMOGENOUS HETROGENOUS
Separation of mixtures
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Separate mixtures based on different physical properties of the components
Different Physical Property
Boiling Point State of Matter (solid/liquid/gas) Adherence to a Surface Volatility Density
Technique
Distillation Filtration Chromatography Evaporation Centrifugation & Decanting
Distillation Filtration
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: carbon Co: 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 2 : carbon dioxide CO: carbon monoxide
Learning Check: 1.
How do elements relate to compounds?
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How do elements and compounds relate to mixtures?
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What is the main difference between pure substances and mixtures?
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Learning Check: How do elements relate to compounds? Compounds are made from elements chemically combined.
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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. (Don’t use water as an example, too easy!!)
Changes in matter
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Identify properties as extensive or intensive.
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Define a physical property and a chemical property.
Describe a physical change.
Describe what happens during a chemical change.
Identify clues that a chemical change has taken place.
Changes in matter Physical change : same substance remains after change.
Ex. Pounding, cutting, dissolving Changes of state: melting, boiling, condensing, etc.
Chemical change: a new substance (different characteristics) appears after the change. (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, mass of products is equal to mass of 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 amount of matter present. Ex. Mass, length, volume Intensive: do not depend on 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. Indicating it does not react is also a chemical property.
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) YouTube - "Cool" Reaction: Ammonium Thiocyanate and Barium Hydroxide Octahydrate Exothermic: energy is released to the surroundings. (Ex. fire) YouTube - Exothermic reaction Potassium Permanganate
Learning check: 1.
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Classify the following as a chemical or physical property Is red Reacts with water Boils at 88 C Dissolves in gasoline Is corrosive 2.
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Classify the following as a chemical or physical change Alcohol evaporating An explosion Digesting food Salt dissolving in water Grass growing
Learning check: 1.
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Classify the following as a chemical or physical property Is red physical Reacts with water Boils at 88 C chemical physical Dissolves in gasoline Is corrosive physical chemical 2.
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Classify the following as a chemical or physical change Alcohol evaporating An explosion Digesting food Salt dissolving in water chemical physical Grass growing physical chemical chemical
Classwork: pg 62 #6-8