Section 3.1 The Elements

Transcription

1 Is Kr the symbol for Kryptonite?

2 Objectives 1. To learn about the relative abundances of the elements 2. To learn the names of some elements 3. To learn the symbols of some elements F is for Fluorine What will Beryllium Xe Be? Boron = B Carl Sagan - Everything

3 All of the materials in the universe can be chemically broken down into about 110 different elements. Compounds are made by combining atoms of the elements just as words are constructed from the letters in the alphabet but rules apply to govern the combinations. Words Compounds

4 A. Abundances of Elements Nine elements account for about 98% of the earth s crust, oceans and atmosphere. Crust

5 A. Abundances of Elements The elements in living matter are very different from those in the earth s crust In the human body, oxygen, carbon, hydrogen and nitrogen are the most abundant elements.

6 Element can have several scientific meanings Element Microscopic form Single atom of that element Element Macroscopic form Sample of that element large enough to weigh on a balance Element Generic form When we say the human body contains the element sodium or lithium, we do not mean that free elemental sodium or lithium is present. Rather we mean that atoms of these elements are present in some form.

7 B. Names and Symbols for the Elements Each element has a name and a symbol. The symbol usually consists of the first one or two letters of the element s name. Oxygen O Krypton Kr Sometimes the symbol is taken from the element s original Latin or Greek name. Examples: gold Au aurum lead Pb plumbum - Sometimes the first and another letter is used Zinc Zn Arsenic As In your notes write the symbol of the 10 most common elements of the Earth s crust and in the human body next to their names

8 Element Hangman Give the symbol for the following elements: Carbon Cobalt Cesium Calcium Copper Chlorine Cadmium Cerium

9 Objectives 1. To understand and illustrate the Law of Constant Composition 2. To learn about Dalton s theory of atoms 3. To learn how a formula describes a compound s composition Dalton Intro

10 1) Law of Constant Composition (1799 Joseph Louis Proust) A given compound always contains the same proportion by mass of the elements of which it is composed. ü A mixture can have variable composition but the composition of a compound is fixed ü Does this give us a clue about the nature of matter? H 2 O = H 2 O = H 2 O = H 2 O

11 2) Law of Multiple Proportions (1803 John Dalton) Different compounds formed by two elements have whole number ratios between their formulas

12 Dalton s Atomic Theory (John Dalton ) Dalton s Atomic Theory states: All elements are composed of atoms All atoms of a given element are identical Atoms of different elements are different Compounds consist of combinations of atoms of different elements Atoms are not created or destroyed in a chemical reaction Dalton in Space You have 90 seconds to memorize these 5 parts of the theory!!

13 Brownian Motion Visual Evidence for Atoms Observed by Robert Brown Pollen particles on the surface of water Brownian Motion Used in 1905 by Einstein to support the existence of atoms Electron Microscope

14 Formulas of Compounds A compound is represented by a chemical formula in which the number and kind of atoms present is shown by using the element symbols and subscripts. Example: the simple sugar, glucose

15 Put your notes away and write a set of rules for how to write a formula of a compound. Be as complete as you can be using what you have learned throughout your course

16 B. Formulas of Compounds 1. Each atom present is represented by its element symbol. 2. The number of each type of atom is indicated by a subscript written to the right of the element symbol. 3. When only one atom of a given type is present, the subscript 1 is not written. 4. Write a metallic element first if present (MgCl 2 ) 5. Write the central atom of a molecule first (PCl 5 ) 6. Write Carbon first and Hydrogen second for an organic molecule (C 6 H 12 O 6 )

17 Formulas of compounds Write the formulas for the following compounds: A phosphorus atom bonded to three chlorine atoms A molecule containing two boron atoms and six hydrogen atoms A compound containing one calcium atom for every two chlorine atoms Four hydrogen atoms bonded to a single carbon atom A compound containing two iron atoms for every three oxygen atoms A molecule of aspirin (acetylsalicylic acid four oxygen atoms, eight hydrogen, nine carbon atoms)

18 Aspirin, acetylsalicylic acid, C 9 H 8 O 4 Aspirin in Motion Element Hangman

19 Dalton described the atomic nature of matter is that the end of the story?

20 Objectives 1. To learn more about how the understanding of atomic structure developed 2. To learn about the internal parts of an atom 3. To understand Rutherford s experiment 4. To describe some important features of subatomic particles 5. To learn about the terms isotope, atomic number, and mass number 6. To understand the use of the symbol to describe a given atom

21 A. The Structure of the Atom Experiments by J.J. Thomson in the 1890 s showed that atoms contain electrons. Cathode ray tube The Discovery of the Electron Electric Potential = Voltage

22 A. The Structure of the Atom The Plum Pudding (Chocolate Chip Cookie) Model The Discovery of the Electron

23 A. The Structure of the Atom Rutherford s Experiment (1911) α particles are very small and positively charged

24 A. The Structure of the Atom Results of the Rutherford experiment (a) The results that the metal foil experiment would have yielded if the plum pudding model had been correct (b) Actual results

25 B. Introduction to the Modern Concept of Atomic Structure Ernest Rutherford showed that atoms have internal structure. The nucleus, which is at the center of the atom, contains protons (positively charged) and neutrons (uncharged). Negatively charged electrons move around the nucleus. The Discovery of the Atomic Nucleus

26 B. Introduction to the Modern Concept of Atomic Structure Comparing the Parts of an Atom

27 Large Hadron Collider Video New Scientist Video Circular tunnel 27km in circumference near Geneva Protons or lead nucleii smashed into targets $4 billion cost limited operation to date 2011 Restart

28 C. Atoms and Isotopes Atoms are made of protons neutrons and electrons Atoms of an element all have the same number of protons the number of protons defines the atom as being of that element In a neutral atom the number of electrons equals the number of protons plus charge is balanced out by minus charge However for a given element the number of neutrons can vary from atom to atom The different versions of atoms of an element are called isotopes Isotopes of an element all have the same chemical properties

29 C. Isotopes Isotopes are atoms with the same number of protons but different numbers of neutrons. Draw a similar picture for 15 N

30 C. Isotopes A particular isotope is represented by the symbol. The atomic number, Z, shows the number of protons The mass number, A, shows the number of protons plus neutrons e.g. Carbon: How many protons and neutrons in each of 12 C, 13 C and 14 C? D 2 O video

31 Isotopes True or False? Atoms that have the same number of neutrons but different numbers of protons are called isotopes True or False? The mass number of a nucleus represents the number of protons in the nucleus Are all atoms of the same element identical? If not, how do they differ? Is this consistent with Dalton s atomic theory? True or False? Isotopes of an element have different chemical properties True or False? All isotopes of an element are stable Dynamic Periodic Table

32 Isotope Math How Many Protons, Neutrons and Electrons in..? Ni Ti 35 Cl 11 B 106 Ag + 45 Ca 2+

33 More Isotope Math What is the symbol for the isotopes below? Z = 8, number of neutrons = 9 Isotope of chlorine with A = 37 Z = 27, A = 60 Number of protons = 26, number of neutrons = 31 The isotope of iodine with a mass number of 131 Z = 3, number of neutrons = 4 Z = 8, number of neutrons = 9, number of electrons = 10 WOC page 88 - Q30 Build An Atom

34 Objectives 1. To learn some features of the Periodic Table 2. To learn some of the properties of metals, nonmetals and metalloids 3. To learn the nature of the common elements

35 A. Introduction to the Periodic Table The periodic table shows all of the known elements in order of increasing atomic number.

36 A. Introduction to the Periodic Table The periodic table is organized to group elements with similar properties in vertical columns.

37 Introduction to the Periodic Table Give the Symbol and Name of 5 Elements from the following Groups Halogens Noble Gases Alkali Metals Transition Metals Alkaline Earths Lanthanides Actinides What is the Group number for Oxygen Magnesium Xenon

38 A. Introduction to the Periodic Table Most elements are metals and occur on the left side. The nonmetals appear on the right side. Metalloids are elements that have some metallic and some nonmetallic properties. Computer chips

39 A. Introduction to the Periodic Table Physical Properties of Metals 1. Efficient conduction of heat and electricity 2. Malleability (can be hammered into thin sheets) 3. Ductility (can be pulled into wires) 4. A lustrous (shiny) appearance

40 Tightest frying pan roll The tightest circumference of a 30 centimeter (12-inch) aluminium frying pan, rolled with bare hands in 30 seconds is centimeters (6.87 inches), set by Scott Murphy at the NXB Team Training Center in Myrtle Beach, S.C., on July 30, Guinness Book of Records Frying Pan Roll

41 Elements in the Periodic Table What is the symbol, group number, group name and element classification for:- Sodium Iodine Argon Iron Barium Silicon Uranium Erbium Volatile History pt2 PT PT 1a from 3 minutes PT 1b early attempts PT 2a from 3 minutes PT 2b explanation of PT

42 B. Natural States of the Elements Most elements are very reactive. Elements are not generally found in nature in uncombined form. Exceptions are: Noble metals gold, platinum and silver Noble gases Group 8 but only as mixtures Oxygen and Nitrogen in air mixture Carbon as diamond

43 B. Natural States of the Elements Diatomic Molecules Nitrogen gas contains N 2 molecules. Oxygen gas contains O 2 molecules.

44 B. Natural States of the Elements Diatomic Molecules

45 HONClBrIF HONClBrIF HONClBrIF HONClBrIF

46 B. Natural States of the Elements Elemental Solids Can exist as Allotropes Carbon atoms Diamond Graphite Buckminsterfullerene Graphene

47 507-Carat Diamond Found at South African Mine Graphite Diamond Planet

48 Elements in the Periodic Table Give the element classification (metal, non-metal, metalloid) and natural state (solid, liquid, gas) (atom, molecule)? of: Potassium Chlorine Neon Tungsten Magnesium Germanium Iodine Mercury

49 Objectives 1. To describe the formation of ions from their parent atoms 2. To learn to name ions 3. To predict which ion a given element forms by using the periodic table 4. To describe how ions combine to form neutral compounds +/- e-

50 A. Ions In a chemical reaction atoms can form ions by gaining or losing electrons. Metals tend to lose one or more electrons to form positive ions called cations. Cations are generally named by using the name of the parent atom.

51 A. Ions Nonmetals tend to gain one or more electrons to form negative ions called anions. Anions are named by using the root of the atom name followed by the suffix ide.

52 A. Ions Ion Charges and the Periodic Table The ion that a particular atom will form can be predicted from the periodic table. Elements in Group 1 and 2 form 1+ and 2+ ions, respectively Group 7 atoms form anions with 1- charges Group 6 atoms form anions with 2- charges Elements close to the sides of the Periodic Table gain or lose electrons to reach a noble gas configuration

53 A. Ions Ion Charges and the Periodic Table

54 Ions What ions would be formed from the elements with the following atomic numbers? Also what noble gas has the same number of electrons as these ions?

55 B. Compounds That Contain Ions Ions are produced in chemical reactions Ions combine to form ionic compounds - Positive ions are attracted to negative ions Formation of NaCl Properties of ionic compounds Solid, crystalline - High melting points (NaCl 801oC)

56 B. Compounds That Contain Ions Properties of Ionic Compounds (2) Can conduct electricity If melted If dissolved in water

57 B. Compounds That Contain Ions Ionic compounds are electrically neutral. The pluses are balanced by the minuses The charges on all the anions and cations in the compound must sum to zero / be in balance. Remember This

58 B. Compounds That Contain Ions Formulas for Ionic compounds Write the cation element symbol followed by the anion element symbol. The number of cations and anions must be correct for their charges to sum to zero.

59 Ionic Compounds What compound would be formed by the following ions? Na+ and Cl- K+ and F- Fe3+ and P3- Na+ and S2- Mg2+ and Cl- Mg2+ and O2- Fe3+ and Cl- Na+ and P3- Al3+ and S2- Mg2+ and N3- What would be the symbol of the ion formed by the Nitrogen-15 isotope?