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The Periodic Table Chapter 12 Lesson 2 Pages E14 – E21
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Objectives Recognize that the elements are organized according to their properties in a chart called the periodic table of the elements. Recognize that there are more than 100 known elements, and each can be identified by its symbol. Observe that elements are grouped into three “classes”: metals, nonmetals, and semimetals.
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450 B.C. Greek philosopher Empedocles (ehm PEHD uh kleez) all matter made up of four elements –Earth –Air –Fire –Water
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1600’s English chemist, Robert Boyle, argued earth, air, fire, and water could not be real elements.
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1700’s French chemist, Antoine-Laurent Lavoisier\ Made one of the first modern lists of chemical elements
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1800’s Many new elements being identified Scientist realizing some elements had similar properties Began organizing elements into families, or groups, with similar properties Still no standardized way of classifying elements
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1869 Russian chemist Dmitri Mendeleyev Developed a way to arrange and classify elements
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Mendeleyev arrangement FIRST –Listed the elements in order of increasing mass –Noticed a repeating pattern NEXT –Rearranged the list so elements with similar properties would appear in the same columns of his table –He left empty spaces for future elements that were discovered
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PERIODIC TABLE A table in which the elements are arranged by their properties The periodic table is standardized –This means scientist all over the world use the same one
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Why is the table called periodic? Mendeleyev discovered the properties of elements have a repeating pattern The word periodic means “repeating”
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The modern periodic table arranges the elements by their? properties
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The Periodic Table Modern periodic table elements are arranged in order of increasing atomic number This means= the number of protons in their nuclei
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Understanding the table Each element box: –Lists the atomic number –Chemical symbol (abbreviation of the element’s name, sometimes from Greek or Latin) –Name –Often included is also the mass
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Understanding the Table Each Column: –Called a group –They have similar properties –Look at copper (Cu), silver (Ag), and gold (Au) on page E17 –These three elements are all soft, shiny metals
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Understanding the Table Horizontal Rows: –Called periods –They have an increasing number of elements –Two rows are pulled out to keep the table from getting to long
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Classification of Elements METALS – are usually shiny, can be bent or stretched, and conduct electricity NONMETALS – most are gases. Solid nonmetals are usually dull in color, do not conduct electricity, do not bend or stretch, and break SEMIMETALS – have characteristics of metals and nonmetals
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Look at the periodic table page E17 Can you find a pattern of metals, nonmetals, and semimetals in the table? Do you think an element found on the bottom left-hand side of the periodic table is a metal, a semimetal, or a nonmetal? Most metals are found on the lower left-hand side of the table, so I would say probably a metal
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Chemical symbols are different colors The color of the symbol tells you if the element is a solid, liquid, or gas at room temperature Most are solids
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METALS Properties: –Luster – the ability to reflect light –Bendable by force or heating –Can be stretched or pulled into thin wires –Conduct electricity
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Metals Found in your body and foods Bones & teeth calcium Blood iron Most metals found in living things combine with other elements in chemical compounds
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SEMIMETALS Have properties of both metals and nonmetals Silicon is a semimetal 28% of Earth’s crust is silicon 2 nd most common element Sand a compound of silicon & oxygen
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Silicon A semi-conductor Under some circumstances silicon conducts electricity and at other times it does not Adding elements to silicon changes its conductivity Silicon is used to make electric circuits found in computer chips
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NONMETALS & Nobel Gases Solid nonmetals do not conduct electricity and dull in color They are brittle (break easy) Example is Sulfur Sulfur used in car batteries Phosphorus – the striking surface of safety matches is a nonmetal
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Nonmetal gases Nitrogen – 78% of the air you breath Oxygen – most abundant element on earth: 21% of air you breath and 47% Earth’s crust Combines with many metals RUST – combination of iron & oxygen
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Last column of periodic table NOBEL GASES – rarely combine with other elements to form compounds Helium – lighter than air Will glow if an electric current is passed through them – Used to make neon signs
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A _____________ is made of two or more elements combined chemically. Compound
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______________ are elements that rarely combine with other elements to form molecules. Nobel Gases
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Elements are arranged by properties in the _______________ Periodic table
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_______________ are usually shiny and bendable. Metals
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An element’s ________________ is an abbreviation of its name, sometimes from Latin or Greek. Chemical symbol
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In the periodic table a column is called a____________. group
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What requires a chemical reaction to form? A compound
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List three properties of metal. Shiny, reflect light, bendable, stretchable, able to conduct electricity and heat
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