slide 1 of 25 © copyright pearson prentice hall your first lab report is due on monday. write down...

of 25 © Copyright Pearson Prentice Hall

Your first lab report is due on Monday.

Write down at least three questions you have about how to do it and we’ll discuss them briefly before beginning today’s lecture.

DO NOW…


TIPS FOR LAB REPORTS

•Include all relevant sections listed on the lab report format reference sheet.

•Make sure your data table has units.

•Show one sample calculation for each type of calculation.

•Write a proper conclusion!

© Copyright Pearson Prentice Hall

Elements and Compounds >

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Distinguishing Elements and Compounds

How are elements and compounds different?

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>Elements and Compounds Distinguishing Elements and Compounds

Element -- the simplest form of matter that has a unique set of properties.

(All of them are listed on the periodic table!)

Ex: carbon, helium, barium, nitrogen, zirconium, phosphorus…

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>Elements and Compounds

A PURE ELEMENT CONTAINS ONLY ONE TYPE OF ATOM

CERTAIN PURE ELEMENTS DO CONTAIN MOLECULES ( DIATOMIC MOLECULES )

When found by themselves, they are ALWAYS in pairs

EX: H-H and O-O

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>Elements and Compounds

Crazy Uncle HOFBrINCl

Hydrogen, Oxygen, Fluorine, Bromine, Iodine, Nitrogen, Chlorine

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Compound -- a substance that contains two or more elements chemically combined in a fixed proportion.

Ex: magnesium oxide (MgO), water (H2O), sodium chloride (NaCl) …

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Breaking Down Compounds

Compounds can be broken down into simpler substances by chemical means, but elements cannot.

Ex: When sugar is heated, it goes through a chemical change.

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Final products

carbon and water vapor

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C12H22O11 C H2O


Distinguishing Elements and Compounds

Properties of Compounds

In general, the properties of compounds are quite different from those of their component elements.

EX: When the elements sodium and chlorine combine chemically to form sodium chloride, there is a change in composition and a change in properties.

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Chlorine is used to kill harmful organisms in swimming pools.

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Sodium is stored under oil to keep it from reacting with oxygen or water vapor in the air. Sodium vapor produces the light in some street lamps.

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Sodium Chloride (commonly known as table salt) is used to season or preserve food.

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Distinguishing Substances and Mixtures

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Substances vs. Mixtures

How can substances and mixtures be distinguished?

If the composition of a material is fixed, the material is a substance.

If the composition of a material may vary, the material is a mixture.


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Elements and Compounds > Distinguishing Substances and Mixtures

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CLASSIFY as Pure Substance( element ), Pure Substance( compound )Homogeneous Mixture, or Heterogeneous Mixture:1.Gasoline2.A stream with gravel at bottom3.Air4.Brass5.Copper metal6.Pure Apple Juice7.Table salt8.Chocolate Chip Cookies


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2.3 Section Quiz

1. Passing an electric current through a certain substance produces oxygen and sulfur. This substance cannot be a(n)

a. compound.

b. mixture.

c. element.

d. solution.


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2.3 Section Quiz

2. Which of the following is a mixture?

a. sodium chloride

b. carbon dioxide

c. sucrose

d. air



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Symbols and Formulas

Symbols and Formulas

What do chemists use to represent elements and compounds?

SYMBOLS!! You’ll start memorizing some next week

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