1 Chapter 11 THE CHEMICAL ELEMENTS Dr. Babar Ali

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

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 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 PERIODIC TABLE Metals Non-metals Metalloids

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

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

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

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

15 More on GROUPS  Elements in groups 1-2 and 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 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 SOME COMMON SOLUTIONS SolutionSoluteSolvent airoxygennitrogen soda watercarbon dioxidewater antifreezeethylene glycolwater wineethyl alcoholwater saltwatersaltwater brasscopperzinc steelcarboniron

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

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

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

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 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 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 THE END