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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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welcome to chemistry

WELCOME TO CHEMISTRY

With Dr. Wieser

chapter 1 section 1
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.
slide3

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
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.
slide5

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

slide6

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

  • Solid
  • Liquid
  • Gas
  • Plasma (found in the interior of the sun)
slide7

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.
slide8

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?
slide9

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.
slide10

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.
slide11

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
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
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.
slide14

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
The Scientific Method
  • Observation
  • Hypothesis
  • Observation or experiment
  • Theory
  • Observation or experiment
  • Law
  • See page 31
slide16
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.
slide17
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.
slide18
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.
slide19
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
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?
slide21

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.
slide22

Some for you to try:

  • a. 1.34 g to kg
  • b. 15.2 cm to m
  • c. 2580. mg to kg
slide23

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)
slide24

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.
slide25

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.
slide26

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
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
slide29

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
slide30

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
slide31

Mixtures

    • composed of two or more substances
    • homogeneous mixtures
    • heterogeneous mixtures