1. 1 Chapter 11 THE CHEMICAL ELEMENTS Dr. Babar Ali

2. 2 CHAPTER OUTLINE  Chemistry & Matter Chemistry & Matter  Classification of Matter Classification of Matter  Mixtures Mixtures  Pure substances Pure substances  Periodic Table Periodic Table  Metals & Non-metals Metals & Non-metals  Metalloids Metalloids  Periods & Groups Periods & Groups  Solutions Solutions  Chemical Formulas Chemical Formulas  Naming Compounds Naming Compounds

3. 3 CHEMISTRY & MATTER  Chemistry is the science that deals with the composition and structure of matter, and its changes  Matter is anything that has mass, and occupies space  Matter can be classified by its physical state as gas, liquid or solid  Matter can also be classified by its composition as pure substance or mixture

4. 4 CLASSIFICATION OF MATTER MATTER Anything that has mass PURE SUBSTANCE Fixed composition & properties MIXTURE Variable composition & properties Mixtures can be converted into pure substances by simple physical processes (e.g. filtration, evaporation)

5. 5 MIXTURES HOMOGENEOUS Uniform composition & properties MIXTURE Variable composition & properties HETEROGENEOUS Non-uniform composition & properties Tea, Coke Ink Salad dressing Cement

6. 6 PURE SUBSTANCES PURE SUBSTANCE Fixed composition & properties COMPOUNDS 2 or more elements chemically combined ELEMENTS Composed of one type of atom Compounds can be converted into elements by chemical processes or reactions (e.g. electrolysis) hydrogen, copper, iron water, sugar salt

7. 7 PERIODIC TABLE  Arrangement of elements based on their atomic masses (A) was first proposed by the Russian chemist, Dmitri Mendeleev in 1869  In the modern periodic table the elements are arranged according to their atomic # (Z)  The elements are generally classified as metals, nonmetals and metalloids

8. 8 PERIODIC TABLE Metals Non-metals Metalloids

9. 9 PERIODIC TABLE Metallic character increases going down a group Metallic character decreases going across a period Most metallic elements Least metallic element

10. 10 PERIODIC TABLE Metals Non-metals Metalloids 7 elements exist as diatomic molecules  others exist as monatomic (one atom)

11. 11 PROPERTIES OF METALS & NON-METALS MetalsNon-metals  Mostly solid  Can be solid, liquid or gas  Have shiny appearance  Have dull appearance  Good conductors of heat & electricity  Poor conductors of heat & electricity  Malleable & ductile  Brittle (if solid)  Lose electrons  Gain or share electrons

12. 12 METALLOIDS  Metalloids are elements that possess some properties of metals and some of non-metals  The most important metalloids are silicon (Si) and germanium (Ge) which are used extensively in computer chips

13. 13 PERIODS & GROUPS  The periodic table is composed of periods (rows) and groups or families (columns)

14. 14 PERIODS & GROUPS  Elements in the same group or family have similar properties, and are commonly referred to by their traditional names

15. 15 More on GROUPS  Elements in groups 1-2 and 13-18 are referred to as main-group or representative groups  Alkali metals are soft metals that are very reactive. They often react explosively with other elements  Noble gases are unreactive gases that are commonly used in light bulbs  Halogens are the most reactive nonmetals, and occur in nature only as compounds  Group 2 elements are called alkaline-earth metals. These metals are less reactive than alkali metals  The group of metals in between the main group elements are called transition metals

16. 16 SOLUTIONS  Solutions are homogeneous mixtures made from two substances Solutions SoluteSolvent Substance being dissolved Substance dissolving solute Solutes and solvents can be any of the 3 phases of matter: solids, liquid or gas

17. 17 SOME COMMON SOLUTIONS SolutionSoluteSolvent airoxygennitrogen soda watercarbon dioxidewater antifreezeethylene glycolwater wineethyl alcoholwater saltwatersaltwater brasscopperzinc steelcarboniron

18. 18 SOLUTIONS  Most common solutions have water as solvent and are called aqueous  Solutions that do not contain the maximum amount of solute dissolved in them are called unsaturated  Solutions that contain the maximum amount of solute dissolved in them and cannot dissolved anymore solute are called saturated  Solutions that contain more than the maximum amount of solute dissolved in them are called supersaturated  Supersaturated solutions are unstable and can be made to form crystals with the slightest disturbance

19. 19 Rules about CHEMICAL FORMULAS  Elements combine chemically to form compounds  Each represented by a chemical formula  The more metallic element is written first followed by the less metallic element  Subscripts are used to indicate the # of atoms of each element in the compound

20. 20 CHEMICAL FORMULAS NaCl Indicates 1 atom of sodium Indicates 1 atom of chlorine More metallic Less metallic

21. 21 CHEMICAL FORMULAS CO2CO2 Indicates 1 atom of carbon Indicates 2 atoms of oxygen More metallic Less metallic

22. 22 CHEMICAL FORMULAS H2SO4H2SO4 Indicates 2 atoms of hydrogen Indicates 4 atoms of oxygen Indicates 1 atom of sulfur

23. 23 CHEMICAL FORMULAS Ca(NO 3 ) 2 Indicates 1 atom of calcium Indicates a nitrate group Composed of 1 nitrogen and 3 oxygens Indicates 2 nitrate groups

24. 24 NAMING Binary COMPOUNDS To name a binary (2-element) compound of a metal and non-metal, 1 st name the metal followed by the non-metal with ending changed to –ide. Binary compounds of a Metal & a Non-metal NaClsodium chloride Al 2 O 3 aluminum oxide Ca 3 N 2 calcium nitride

25. 25 NAMING COMPOUNDS To name a binary compound of 2 non-metals, the more metallic element is written 1st, followed by the 2 nd element with the –ide ending Binary compounds of a 2 Non-metals HClhydrogen chloride CS 2 carbon disulfide PBr 3 phosphorous tribromide The number of atoms for each element is indicated by Greek prefixes: mono-(1); di-(2); tri-(3);tetra-(4); penta-(5); hexa-(6); hepta-(7)

26. 26 THE END