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WELCOME TO CHEMISTRY. With Dr. Wieser. Chapter 1 Section 1. Chemistry can be defined as the study of matter. Matter is anything that has mass and occupies space. So chemistry is the study of pretty much everything.

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With Dr. Wieser

Chapter 1 Section 1

  • Chemistry can be defined as the study of matter.

  • Matter is anything that has mass and occupies space. So chemistry is the study of pretty much everything.

  • We will focus on the structure of matter and the changes that matter can undergo.

  • A chemical is defined as any substance that has a definite composition.

  • Look around the room-how many chemicals can you observe?

  • There are many different branches of Chemistry. See p4.

  • Also on PP4-5-different types of research are discussed.

Section 2 Matter & Its Properties

  • We can define matter as anything that has mass and occupies space. All matter is composed of atoms. Elements and compounds are made up of atoms.

  • An atom is the smallest unit of an element that has the properties of that element. An element is a pure substance and can not be broken down into simpler substances.

  • A compound is a pure substance that is made of two or more elements that can be broken down into simpler substances.

  • Matter can exist in four states (three are found on Earth)

  • Solid

  • Liquid

  • Gas

  • Plasma (found in the interior of the sun)

  • Note that energy must be supplied to go from one state or phase to another:

  • Solid →liquid→gas

  • Solids-have fixed volume and shape.

  • Liquids-have fixed volume but take on the shape of their container.

  • Gases-have neither fixed volume or shape.

  • In addition to phase changes matter can undergo other physical changes:

  • Physical changes do not produce any new substances:

  • What happens to an ice cube when heat is supplied?

  • What about when sugar is dissolved in water?

  • Chemical changes produce new substances.

  • In a chemical reaction one or more substances, the reactants are converted to one or more new substances, the products.

  • A physical property is one that describes a physical change. When considering phase changes, the melting point of a substance is a physical property. In the case of ice, this temperature is______oC.

  • A chemical property describes the chemical change. Paper undergoes a chemical change when it burns, so the ability to react with oxygen is a chemical property of paper.

  • Compounds and elements are both pure substances.

  • Compounds are a chemical combination of two or more elements.

  • Mixtures are a physical combination of two or more pure substances.

  • Mixtures that are uniform in composition are called homogenous mixtures (sugar in water)

  • Mixtures that are not uniform are heterogeneous mixtures (sand in water)

End of Section 2

  • Homework: always due at the beginning of the next class period.

  • P 14 #’s 1-2-4

  • And p22 #’s 10-12

Section 3 Elements

  • I mentioned previously that elements are composed of atoms. The periodic table lists all the known chemical elements.

  • The columns are called groups or families –there are 18 of them.

  • The rows are called periods. (see p 17).

  • There are three types of elements shown on the table.

  • Metals

  • Non-metals

  • Metaloids or semi-metals

  • Pages 18-20 give examples.

  • Homework for section 3

  • Page 20 #’s 1-4

  • END of Chapter 1 a test will follow.

The Scientific Method

  • Observation

  • Hypothesis

  • Observation or experiment

  • Theory

  • Observation or experiment

  • Law

  • See page 31

  • Scientists ask questions and make observations.

  • A hypothesis is a possible explanation for an observation. A hypothesis must be testable-usually by performing an experiment and analyzing the result.

  • Experiments are conducted under controlled conditions.

  • If the results of an experiment may support the hypothesis- which will lead to more experiments or not support it-then you need to look for a new hypothesis or the result may lead you in a whole new direction.

  • If over a relatively long period of time many experiments support the hypothesis then the hypothesis can become a theory.

  • A theory is the best current explanation for a series of observations. If new information becomes available in the future then the theory may be modified or even replaced. This is all part of the scientific method!

  • In the course of performing experiments, sometimes a cause and effect relationship is observed.

  • This relationship is a scientific law-scientific laws do not explain observations but point out connections between observations. For example later in the year we will study the Gas Laws-one says that when the temperature of a gas goes up so does its volume-the theory that explains this observation is called the Kinetic Theory of gases.

Chapter 2

  • One of the key parts of the scientific method is the ability to make measurements.

  • If I told you a measurement was 59.7. What would be your response?

  • The metric system is the one used in science. The units are called SI units-we will see that not all the units we will use are SI units.

  • SI base units are listed on p 34.

  • Some for you to try:

  • a. 1.34 g to kg

  • b. 15.2 cm to m

  • c. 2580. mg to kg

  • Derived units: many measurements use more complicated units derived from the base units. For example volume (l x w x h) requires a cubic unit, if the measurements were in meters the unit would be m3.

  • The non-SI unit we commonly use for volume is the liter which is equivalent to a dm3 or 1000 cm3 (1000 mL)

  • One important physical property of matter is density .

  • Density = mass/volume

  • Every substance has its own unique density.

  • See p 17 for a list.

  • Since the density formula has 3 variables, 3 types of problems are possible.

  • 1. given mass and volume-find density

  • a substance has a mass of 23.2 grams and a volume of 18.5 cm3. Find its density.

  • 2. given density and volume, find mass (g)

  • D = m/V so m=D x V

  • The density of silver is 10.5 g/cm3. Find the mass of a block of silver with a volume of 40.0cm3.

  • 3. Given the density and mass, find the volume of a substance.

  • D= m/V so V= m/D

  • Find the volume of a piece of iron that has a mass of 147grams. (from p 17 density of iron = 7.86 g/cm3)

Chapter 1 Section 3

  • Substances (pure)

  • - matter in which all samples have identical composition and properties.

  • Elements

    • substances that cannot be decomposed into simpler substances via chemical reactions

  • Elemental symbols

    • found on periodic chart

  • Compounds

    • substances composed of two or more elements in a definite ratio by mass

    • can be decomposed into the constituent elements

      • Water is a compound that can be decomposed into simpler substances – hydrogen and oxygen

  • The properties(chemical and physical) of compounds are unique and are totally different from the elements that make up the compound.

  • Sodium chloride for example.

  • NaCl

  • Mixtures

    • composed of two or more substances

    • homogeneous mixtures

    • heterogeneous mixtures

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