1. Chemistry Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

2. 2 Chemistry: A Science for the 21 st Century Health and Medicine Sanitation systems Surgery with anesthesia Vaccines and antibiotics Gene therapy Energy and the Environment Fossil fuels Solar energy Nuclear energy

3. 3 Chemistry: A Science for the 21 st Century Materials and Technology Polymers, ceramics, liquid crystals Room-temperature superconductors? Molecular computing? Food and Agriculture Genetically modified crops “Natural” pesticides Specialized fertilizers

4. 4 The Study of Chemistry MacroscopicMicroscopic

5. 5 The scientific method is a systematic approach to research. A hypothesis is a tentative explanation for a set of observations. tested modified

6. 6 A theory is a unifying principle that explains a body of facts and/or those laws that are based on them. A law is a concise statement of a relationship between phenomena that is always the same under the same conditions. Atomic Theory Force = mass x acceleration

7. 7 Matter is anything that occupies space and has mass. A substance is a form of matter that has a definite composition and distinct properties. Chemistry is the study of matter and the changes it undergoes. liquid nitrogen gold ingots silicon crystals

8. 8 A mixture is a combination of two or more substances in which the substances retain their distinct identities. 1. Homogenous mixture – composition of the mixture is the same throughout 2. Heterogeneous mixture – composition is not uniform throughout soft drink, milk, solder cement, iron filings in sand

9. 9 Physical means can be used to separate a mixture into its pure components. magnet distillation

10. 10 An element is a substance that cannot be separated into simpler substances by chemical means. 114 elements have been identified 82 elements occur naturally on Earth gold, aluminum, lead, oxygen, carbon, sulfur 32 elements have been created by scientists technetium, americium, seaborgium

11. 11 Replace with Table 1.1 from 7e page 6

12. 12 A compound is a substance composed of atoms of two or more elements chemically united in fixed proportions. Compounds can only be separated into their pure components (elements) by chemical means. lithium fluoride quartz dry ice – carbon dioxide

13. 13 Classification of Matter Replace with Table 1.5 from 7e page 7

14. 14 A Comparison: The Three States of Matter

15. 15 The Three States of Matter: Effect of a Hot Poker on a Block of Ice

16. 16 A physical change does not alter the composition or identity of a substance. A chemical change alters the composition or identity of the substance(s) involved. ice melting sugar dissolving in water hydrogen burns in air to form water Types of Changes

17. 17 An extensive property of a material depends upon how much matter is being considered. An intensive property of a material does not depend upon how much matter is being considered. mass length volume density temperature color Extensive and Intensive Properties

18. 18 Matter - anything that occupies space and has mass mass – measure of the quantity of matter SI unit of mass is the kilogram (kg) 1 kg = 1000 g = 1 x 10 3 g weight – force that gravity exerts on an object A 1 kg bar will weigh 1 kg on earth 0.1 kg on moon weight = c x mass on earth, c = 1.0 on moon, c ~ 0.1

19. Atoms, Molecules, and Ions

20. 20 Dalton’s Atomic Theory (1808) 1. Elements are composed of extremely small particles called atoms. 2. All atoms of a given element are identical, having the same size, mass and chemical properties. The atoms of one element are different from the atoms of all other elements. 3. Compounds are composed of atoms of more than one element. In any compound, the ratio of the numbers of atoms of any two of the elements present is either an integer or a simple fraction. 4. A chemical reaction involves only the separation, combination, or rearrangement of atoms; it does not result in their creation or destruction.

21. 21 Dalton’s Atomic Theory Law of Multiple Proportions

22. 22 8 X 2 Y 16 X8 Y + Law of Conservation of Mass

23. 23 J.J. Thomson, measured mass/charge of e - (1906 Nobel Prize in Physics) Cathode Ray Tube

24. 24 Cathode Ray Tube

25. 25 e - charge = -1.60 x 10 -19 C Thomson’s charge/mass of e - = -1.76 x 10 8 C/g e - mass = 9.10 x 10 -28 g Measured mass of e - (1923 Nobel Prize in Physics) Millikan’s Experiment

26. 26 (uranium compound) Types of Radioactivity

27. 27 Thomson’s Model

28. 28 Rutherford and the Nuclear Atom Ernest Rutherford directed Hans Geiger and Ernst Marsden’s experiment in 1910. –  - particle scattering from thin Au foils – Gave us the basic picture of the atom’s structure.

29. 29 1.atoms positive charge is concentrated in the nucleus 2.proton (p) has opposite (+) charge of electron (-) 3.mass of p is 1840 x mass of e - (1.67 x 10 -24 g)  particle velocity ~ 1.4 x 10 7 m/s (~5% speed of light) (1908 Nobel Prize in Chemistry) Rutherford’s Experiment

30. 30 Rutherford and the Nuclear Atom In 1912 Rutherford decoded the  -particle scattering information. – Explanation involved a nuclear atom with electrons surrounding the nucleus.

31. 31 Rutherford and the Nuclear Atom Rutherford’s major conclusions from the  -particle scattering experiment 1.The atom is mostly empty space. 2.It contains a very small, dense center called the nucleus. 3.Nearly all of the atom’s mass is in the nucleus. 4.The nuclear diameter is 1/10,000 to 1/100,000 times less than atom’s radius.

32. 32 Rutherford and the Nuclear Atom Because the atom’s mass is contained in such a small volume: – The nuclear density is ~10 15 g/mL. – This is equivalent to ~3.72 x 10 9 tons/in 3. – Density inside the nucleus is almost the same as a neutron star’s density.

33. 33 atomic radius ~ 100 pm = 1 x 10 -10 m nuclear radius ~ 5 x 10 -3 pm = 5 x 10 -15 m Rutherford’s Model of the Atom “If the atom is the Houston Astrodome, then the nucleus is a marble on the 50-yard line.”

34. 34 Chadwick’s Experiment (1932) (1935 Noble Prize in Physics) H atoms: 1 p; He atoms: 2 p mass He/mass H should = 2 measured mass He/mass H = 4  + 9 Be 1 n + 12 C + energy neutron (n) is neutral (charge = 0) n mass ~ p mass = 1.67 x 10 -24 g

35. 35 mass p ≈ mass n ≈ 1840 x mass e -

36. 36 Atomic number (Z) = number of protons in nucleus Mass number (A) = number of protons + number of neutrons = atomic number (Z) + number of neutrons Isotopes are atoms of the same element (X) with different numbers of neutrons in their nuclei X A Z H 1 1 H (D) 2 1 H (T) 3 1 U 235 92 U 238 92 Mass Number Atomic Number Element Symbol Atomic Number, Mass Number, and Isotopes

37. 37 The Isotopes of Hydrogen

38. 38 A molecule is an aggregate of two or more atoms in a definite arrangement held together by chemical forces. H2H2 H2OH2ONH 3 CH 4 A diatomic molecule contains only two atoms: H 2, N 2, O 2, Br 2, HCl, CO A polyatomic molecule contains more than two atoms: O 3, H 2 O, NH 3, CH 4 diatomic elements

39. 39 An ion is an atom, or group of atoms, that has a net positive or negative charge. cation – ion with a positive charge If a neutral atom loses one or more electrons it becomes a cation. anion – ion with a negative charge If a neutral atom gains one or more electrons it becomes an anion. Na 11 protons 11 electrons Na + 11 protons 10 electrons Cl 17 protons 17 electrons Cl - 17 protons 18 electrons

40. 40 A monatomic ion contains only one atom: A polyatomic ion contains more than one atom: Na +, Cl -, Ca 2+, O 2-, Al 3+, N 3- OH -, CN -, NH 4 +, NO 3 -

41. 2.1 Give the number of protons, neutrons, and electrons in each of the following species: (a) (b) (c) (d) carbon-14

42. 2.1 Strategy Recall that the superscript denotes the mass number (A) and the subscript denotes the atomic number (Z). Mass number is always greater than atomic number. (The only exception is H, where the mass number is equal to the atomic number.) In a case where no subscript is shown, as in parts (c) and (d), the atomic number can be deduced from the element symbol or name. To determine the number of electrons, remember that because atoms are electrically neutral, the number of electrons is equal to the number of protons.

43. 2.1 Solution (a) The atomic number is 11, so there are 11 protons. The mass number is 20, so the number of neutrons is 20 − 11 = 9. The number of electrons is the same as the number of protons; that is, 11. (b) The atomic number is the same as that in (a), or 11. The mass number is 22, so the number of neutrons is 22 − 11 = 11. The number of electrons is 11. Note that the species in (a) and (b) are chemically similar isotopes of sodium.

44. 2.1 (c) The atomic number of O (oxygen) is 8, so there are 8 protons. The mass number is 17, so there are 17 − 8 = 9 neutrons. There are 8 electrons. (d) Carbon-14 can also be represented as 14 C. The atomic number of carbon is 6, so there are 14 − 6 = 8 neutrons. The number of electrons is 6.