Outline Chapter 10 The Periodic Law

Transcription

1 Outline Chapter 10 The Periodic Law Chemical Change Three Classes of Matter The Atomic Theory Metals and Nonmetals Chemical Activity Families of Elements The Periodic Table Groups and Periods Shells and Subshells Explaining the Periodic Table Types of Bonding Covalent Bonding Ionic Bonding Ionic Compounds Atom Groups Naming Compounds Chemical Equations 1

2 10-1. Chemical Change The medieval search for a way to change ordinary metals into gold is called alchemy. A chemical reaction results in the formation of a new substance whose properties are different from those of the individual substances that participate in the reaction. 2

3 10-2. Two Classes of Matter Two classes of matter are Pure Substances, and mixtures. Chemical Process/ Properties Physical Process/ Properties 3

4 10-2. Two Classes of Matter The difference between a mixture and pure substance. 4

5 10-2. Two Classes of Matter Examples of Chemical and Physical Processes. Chemical Process burning fermentation rusting Chemical Property combustible reactive Edible Physical Process Filtering distillation reverse osmosis Physical Property hardness color texture 5

6 10-2. Two Classes of Matter In a compound, the elements are present in a specific ratio by mass according to the law of definite proportions. In a mixture, the components are not present in a specific ratio by mass. 6

7 10-3. Atomic Theory The English schoolteacher John Dalton ( ) proposed an atomic theory, an old idea from Democritus. Some atoms form molecules. Not all compounds are molecules. 7

8 10-4. Metals and Nonmetals 8

9 10-4. Metals and Nonmetals Metals Nonmetals All metals, except mercury, are solid at room temperature. Metals have a characteristic metallic luster. All metals are opaque. Metals can be shaped by bending or hammering. Metals are good conductors of heat and electricity. Most elements are metals. Nonmetals may be solid, liquid, or gaseous. Nonmetals do not have a luster. Most nonmetals are transparent in thin sheets. Solid nonmetals are brittle. Nonmetals are insulators. 9

10 10-5. Chemical Activity Active elements combine readily to form compounds. Inactive elements have little tendency to react chemically. Active elements liberate more heat when they react than do inactive elements. Active elements usually form stable compounds. 10

11 10-6. Families of Elements The halogens, or "salt formers," are active nonmetals. They are in group 7. The alkali metals are active metals and have low melting points.they are in group 1. The alkaline earth metals are less active than the alkali metals. They are in group 2. The inert gases are inactive nonmetals. They are in group 8 11

12 10-7. The Periodic Table The Russian chemist Dmitri Mendeleev formulated the periodic law about 1869 which states that when elements are listed in order of atomic number, elements with similar chemical and physical properties appear at regular intervals. The periodic table is a listing of the elements according to atomic number in a series of rows such that elements with similar properties form vertical columns. 12

13 10-8. Groups and Periods The periodic table arranges chemical families of elements in vertical columns called groups. The horizontal rows of elements of the periodic table are called periods. The transition elements are placed between groups 2 and 3 and include: the rareearth metals (atomic numbers 57-71), the actinides (atomic numbers ). 13

14 10-9. Shells and Subshells The electrons in an atom that have the same principal quantum number n occupy the same shell. The electrons in an atom that have the same orbital quantum number l occupy the same subshell. The larger the value of l, the more electrons the subshell can hold. A shell or subshell that contains its full quota of electrons is said to be closed. 14

15 Explaining the Periodic Table The Grand Secret of Chemistry-All atoms want to become like the noble gases with filled shells or electronic orbitals. They do this by gaining or losing electrons to become ions. 15

16 Types of Bonds Covalent Bonds (share electrons) Ionic Bonds (transfer electrons) Held together by electrostatic attractions (+ and ions attract) Metallic Bonds (sea of electrons) 16

17 The Covalent Bond Covalent compounds are substances whose atoms are joined by one or more pairs of electrons in a covalent bond. 17

18 The Covalent Bond Polar covalent compounds are those in which the shared electron pairs are closer to one atom than to the other, making one part of the molecule relatively negative and another part relatively positive. H δ+ -Cl δ- O δ- H δ+ H δ+ 18

19 Ionic Bond An ionic bond is formed when electrons are transferred between two or more atoms and the resulting ions of opposite charge attract each other. 19

20 Ionic Compounds When a metal atom combines with a nonmetal atom to form an ionic compound, the chemical formula of the ionic compound formed can be determined by knowing how many electrons the metal atom loses and how many electrons the nonmetal atom gains. 20

21 Ionic Compounds What ionic compounds can you make from the following? Na K Ca Mg Al Cl Br O S N NaCl KBr CaCl 2 MgBr 2 sodium chloride potassium bromide calcium chloride magnesium bromide CaO MgS AlCl 3 K 3 N calcium oxide magnesium sulfide aluminum chloride potassium nitride Al 2 O 3 Aluminum oxide 21

22 Atom Groups Atom groups appear as units in many compounds and remain together during chemical reactions. The sulfate group SO 4 is an example of an atom group. A precipitate is an insoluble solid that results from a chemical reaction in solution. When two or more atom groups of the same kind are present in the formula of a compound, parentheses are placed around the group. Example: Ca(NO 3 ) 2 22

23 Ions of Common Atom Groups Or Polyatomic Ions Ammonium... Nitrate Permanganate Chlorate. Hydroxide. Cyanide. Sulfate... Carbonate.. Chromate.. Silicate.. Phosphate.. NH 4 + NO 3 - MnO 4 - ClO 3 - OH - CN - SO CO 3 2- CrO 4 2- SiO 3 2- PO

24 Naming Compounds A compound ending in -ide usually is composed of only two elements. Hydroxides which contain the OH - ion are an exception. Sodium Chloride=NaCl A compound ending in -ate contains oxygen and two or more other elements. Calcium Sulfate=CaSO 4 When the same pair of elements occurs in two or more compounds, a prefix (mono = 1, di = 2, tri = 3, tetra = 4, penta = 5, hexa =6, and so on) may be used to indicate the number of one or both kinds of atoms in the molecule. Carbon Dioxide = CO 2 When one of the elements in a compound is a metal that can form different ions, the ionic charge of the metal is given by a roman numeral. Copper(II) Chloride= CuCl 2 24

25 Lets Practice! Na 2 CO 3 KMnO 4 NaOH CuSO 4 SnF 2 SnF 4 PbCrO 4 H 2 O NH 3 Sodium carbonate Potassium permanganate Sodium hydroxide Copper (II) sulfate or Cupric sulfate Tin (II) Flouride or Stannous Flouride Tin (IV) Flouride or Stannic Flouride Lead (II) chromate or Plubous chromate Hydrogen oxide (no just water) Nitrogen trihydride (no..just ammonia) 25

26 Taking 20 kids to the zoo? What At who s Parents if you house are came funny would home with you that drop only 22 way! kids? them 18 kids? off? 26

27 Chemical Reactions In a chemical equation the formulas of the reacting substances (reactants) appear on the left-hand side and the formulas of the products appear on the right-hand side. CH 4 + O 2 H 2 O + CO 2 Chemical equations must be balanced, meaning that the number of atoms of each kind of element must be the same on both sides of the equation. Unbalanced chemical equations have unequal numbers of at least one kind of atom on both sides of the equation. Is the reaction below balanced? K 2 CrO 7 + SO 2 K 2 SO 4 + CrO 2 27

28 Balancing using the underline method. Na 2 O(s) + H 2 O(l) 2 NaOH(aq) CH 4 (g) + 2 O 2 (g) CO 2 (g) + 2 H 2 O(g) Fe(s) + O 2 (g) Fe 2 O 3 (s) LiOH(s) + CO 2 (g) LiHCO 3 (s) KClO 3 (s) KCl(s) + O 2 (g) 2 2 MnO

29 Lecture Quiz What type of element is Sulfur, metal or non-metal? 2. What is the difference between a chemical process and a chemical property? 3. What type of bond does KBr have? 4. What would be the name of CaBr 2? 5. What would be the formula for Calcium Carbonate? 29

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31 Lecture Quiz What type of element is Sulfur, metal or nonmetal? Nonmetal 2. What is the difference between a chemical process and a chemical property? Process involves change and property describes something.. 3. What type of bond does KBr have? Ionic 4. What would be the name of CaCl 2? Calcium Chloride 5. What would be the formula for Calcium Carbonate? CaCO 3 31

32 Lecture Quiz What are the two basic types of matter? 2. What are the two basic types of elements? 3. What family is the element calcium in? 4. What would be the name of Al 2 S 3? 5. What would be the formula for Sodium Permanganate? 32

33 Lecture Quiz What are the two basic types of matter? Pure Substances and Mixtures 2. What are the two basic types of elements? Metals and Nonmetals 3. What is the difference between a covalent and an ionic compound? Ionic-complete electron transfer to form ions, covalent-share electrons 4. What would be the name of Al 2 S 3? Aluminuim Sulfide 5. What would be the formula for Sodium Permanganate? NaMnO 4 33