THE PERIODIC TABLE. Chapter 15

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1 THE PERIODIC TABLE Chapter 15

2 MENDELEEV 1869 The first version of the periodic table was published by Dmitri Mendeleev, a Russian chemist He arranged the elements in order of increasing atomic mass This arrangement created a pattern: elements with similar properties fell into groups on the table

3 MENDELEEV

4 MORE MENDELEEV Mendeleev had to leave gaps for elements that had not yet been discovered Due to the groupings in his table, he could predict the properties of those missing elements Within 15 years, other scientists had discovered the missing elements

5 MOSELEY Henry Moseley, an English physicist, improved Mendeleev s Table He arranged the elements by atomic number (increasing number of protons in the nucleus) rather than atomic mass This made it very clear how many elements were still undiscovered

6 TODAY S PERIODIC TABLE The elements are still organized by increasing atomic number The rows (called periods) are labeled 1-7 Period- a row of elements in the periodic table whose properties change gradually and predictably

7 The columns (called groups) are labeled 1-18 Group- contains elements that have similar physical or chemical properties

8 ZONES OF THE PERIODIC TABLE The periodic table is divided into sections The first section contains the elements in Groups 1 and 2 and These 8 groups are the representative elements The representative elements include metals, metalloids, and nonmetals

9 ZONES OF THE PERIODIC TABLE Groups 3-12 are the transition elements These elements are all metals The inner transition elements (the lanthanide and actinide series) are located below the below the main table Why?

10 ZONES OF THE PERIODIC TABLE To save space! The periodic table would be too wide if they were included in the main table (They are called the lanthanide and actinide series because the lanthanide series follows the element lanthanum and the actinide follows actinium)

12 METALS, NONMETALS AND METALLOIDS Metal- an element that has luster, is a good conductor of heat and electricity, and is malleable All metals, except mercury, are solids at room temperature

METALS, NONMETALS AND METALLOIDS Nonmetals- usually

are poor conductors of heat and electricity There

They include carbon, sulfur, nitrogen, oxygen,

13 METALS, NONMETALS AND METALLOIDS Nonmetals- usually gases or brittle solids at room temperature, they are poor conductors of heat and electricity There are only 17 nonmetals, but they are very important. They include carbon, sulfur, nitrogen, oxygen, phosphorous and iodine. Elements we cannot live without!

14 METALS, NONMETALS AND METALLOIDS Metalloids- elements that share some properties with metals and some with nonmetals Metalloids are located between metals and nonmetals on the periodic table

Each element is represented on the periodic table by box called an element key The element key indicates the element s name, atomic number, symbol and average atomic

16 Each element is represented on the periodic table by box called an element key The element key indicates the element s name, atomic number, symbol and average atomic mass There may be a logo indicating whether the element is a solid, liquid or gas at room temperature Balloon- gas, Cube= solid, Drop= liquid Bulls-eye= synthetic elements

17 SYMBOLS FOR THE ELEMENTS The symbols for the elements are either one or two letter abbreviations Usually they make sense for example: O for oxygen Sometimes they are a bit weird for example: Au for gold (Au came from Aurum shining dawn in Latin)

18 REPRESENTATIVE ELEMENTS Chapter 15 Section 2

19 GROUPS 1 AND 2 Always found in nature combined with other elements Called active metals because they like to form compounds with other elements They are all metals except for hydrogen

20 ALKALI METALS Group 1 metals are called Alkali Metals -silvery solids with low densities and low melting points -increase in reactivity (the tendency to combine with other elements) as you move from top to bottom on the periodic table (Sodium chloride in table salt, lithium in batteries)

22 ALKALINE EARTH METALS Group 2 metals are called Alkaline Earth Metals -denser, harder, and has a higher melting point than the alkali metal in the same period -reactive, but not as reactive as the alkali metals (Beryllium in emeralds, Magnesium in chlorophyll)

24 GROUPS These elements are not all solid metals (groups 1 and 2 are all solid metals) One group can have metals, nonmetals, and metalloids One group can contain elements that are solids, liquids, or gases

25 THE BORON FAMILY Group 13 -all metals except for boron (a brittle, black metalloid) -boron-coated cookware won t crack when moved from cold to hot -aluminum is used to make cans, cookware, house siding and baseball bats -gallium is used to make computer chips

26 THE CARBON GROUP Group 14 -carbon is a nonmetal -silicon and germanium are metalloids -tin and lead are metals Carbon exists as an element as diamond and graphite. It is also in all living things Silicon is found in sand (ground up bits of quartz, made of silicon and oxygen)

27 Silicon and germanium, metalloids, are semiconductors Semiconductor Something that doesn t conduct electricity as well as a metal, but conducts electricity better than a nonmetal Semiconductors are most often used in electronics (computer chips)

28 Tin and lead are the heaviest elements in Group 14 -lead is used in car batteries, as protection from nuclear reactors and x-ray equipment -tin is used for pewter and toothpaste

29 THE NITROGEN GROUP Group 15 -Nitrogen and phosphorous are the nonmetals of this group -both are needed by living things -ammonia is a gas that contains nitrogen and hydrogen, when dissolved in water it can be used as a cleaner (Windex), it can also be used as a fertilizer and used to make nylon -phosphorous is needed for healthy teeth and bones -plants also need phosphorous and it is an ingredient in most fertilizers

30 THE OXYGEN GROUP Group 16 -Oxygen and sulfur are necessary for life -tellurium and polonium (the heavier elements in this group) are metalloids ~20% of Earth s atmosphere is oxygen There is a lot of oxygen in rocks and minerals because it easily combines with other elements -sulfur is a solid, yellow nonmetal (very stinky!) -selenium is used in solar cells, copiers, and camera materials because it conducts electricity when exposed to light

THE HALOGEN GROUP Group 17 -all are nonmetals except for astatine (radioactive metalloid) -called halogens because they are salt formers -all halogens form salts with sodium and

31 THE HALOGEN GROUP Group 17 -all are nonmetals except for astatine (radioactive metalloid) -called halogens because they are salt formers -all halogens form salts with sodium and other alkali metals -halogens decrease in reactivity down the group (iodine less reactive than bromine which is less reactive than chlorine which is less reactive than fluorine)

32 THE NOBLE GASES Group 18 -called the noble gases because they like to be alone -they rarely combine with other elements -found in nature as uncombined elements -VERY LOW REACTIVITY

Neon signs do not necessarily contain neon Each noble gas

glows red-orange -argon glows blue Krypton + nitrogen

radioactive gas produced from decaying uranium.

33 Neon signs do not necessarily contain neon Each noble gas produces a different color -Helium glows yellow -neon glows red-orange -argon glows blue Krypton + nitrogen keeps light bulb filaments from burning out Radon is a radioactive gas produced from decaying uranium. It continues to release radiation and if breathed in over time can cause lung cancer

34 TRANSITION ELEMENTS Chapter 15 section 3

35 All the transition elements are metals Across any period, the properties of the transition elements change less noticeably than the representative elements Most of the transition elements are found combined with other elements in ores (minerals or an aggregate of minerals from which a valuable constituent, especially a metal, can be profitably mined or extracted) Few transition elements are found as pure elements (Gold, Silver)

36 THE IRON TRIAD Iron, cobalt, and nickel (all in period 4) have very similar properties and are known as the iron triad Magnetic properties Steel is made from iron + other metals + carbon. The other metals determine how strong the steel is

37 Most transition metals have higher melting points than the representative elements Tungsten has the highest melting point of any metal (3,410C) Mercury has the lowest melting point of any metal (it s a liquid) (-39C) Ruthenium, rhodium, palladium, osmium, iridium and platinum (sometimes referred to as the platinum group do not combine easily with other elements and are often used as catalysts (substances that can speed up reactions but are not themselves changed in the process) Nickel, zinc, and cobalt can also be used as catalysts

38 THE LANTHANIDES Also called rare earths, because once they were thought to be rare (they are, in fact, not so rare) Usually combined with oxygen in Earth s crust Soft metals that can be cut with a knife The elements are very similar and often occur in the same ore

39 THE ACTINIDES All are radioactive Only thorium, protactinium, and uranium are found naturally on Earth Uranium is found in Earth s crust (long half-life, 4.5 billion years) All the other actinides are synthetic elements (made in labs and nuclear reactors) Plutonium fuels nuclear power plants Americium is used in smoke detectors Californium-252 is used in cancer radiation therapy

40 HOW SYNTHETIC ELEMENTS ARE MADE The nuclei of different atoms fuse to form a new (often shortlived) synthetic element. Energy and at least one subatomic particle are usually given off in the process In this reaction, 2 isotopes of hydrogen (tritium and deuterium) are fused to form helium. A neutron and energy are given off.

Chapter: The Periodic Table

Table of Contents Chapter: The Periodic Table Section 1: Introduction to the Periodic Table Section 2: Representative Elements Section 3: Transition Elements 1 Introduction to the Periodic Table Development