1. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Chemistry is the study of the composition, structure, and properties of matter, the processes that matter undergoes, and the energy changes that accompany these processes. Section 1 Chemistry Is a Physical Science Chapter 1

2. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Volume is the amount of three dimensional space an object occupies. Mass is a measure of the amount of matter. Matter is anything that has mass and takes up space. Matter Section 2 Matter and Its Properties Chapter 1

3. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Basic Building Blocks of Matter An atom is the smallest unit of an element that maintains the chemical identity of that element. An element is a pure substance that cannot be broken down into simpler, stable substances and is made of one type of atom. A compound is a substance that can be broken down into simple stable substances. Each compound is made from the atoms of two or more elements that are chemically bonded. Section 2 Matter and Its Properties Chapter 1

4. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Visual Concepts Molecule Chapter 1

5. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Basic Building Blocks of Matter, continued Section 2 Matter and Its Properties Chapter 1

6. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Properties and Changes in Matter Extensive properties depend on the amount of matter that is present. volume mass the amount of energy in a substance. Section 2 Matter and Its Properties Chapter 1

7. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Properties and Changes in Matter Intensive properties do not depend on the amount of matter present. melting point boiling point density ability to conduct electricity ability to transfer energy as heat Section 2 Matter and Its Properties Chapter 1

8. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Properties of Matter Section 2 Matter and Its Properties Chapter 1

9. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Physical Properties and Physical Changes A physical property is a characteristic that can be observed or measured without changing the identity of the substance. melting point and boiling point A physical change is a change in a substance that does not involve a change in the identity of the substance. grinding, cutting, melting, and boiling Section 2 Matter and Its Properties Chapter 1

10. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Physical Properties and Physical Changes, continued A change of state is a physical change of a substance from one state to another. states of matter—solid state, liquid state, gas state, plasma In the solid state, matter has definite volume and definite shape. In the liquid state, matter has a definite volume but an indefinite shape. Section 2 Matter and Its Properties Chapter 1

11. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu In the gas state, matter has neither definite volume nor definite shape. Plasma is a high-temperature physical state of matter in which atoms lose most of their electrons, particles that make up atoms. Physical Properties and Physical Changes, continued Section 2 Matter and Its Properties Chapter 1

12. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Visual Concepts Plasma Chapter 1

13. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Water in Three States Chapter 1

14. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Chemical Properties and Chemical Changes A chemical property relates to a substance’s ability to undergo changes that transform it into different substances A change in which one or more substances are converted into different substances is called a chemical change or chemical reaction. Section 2 Matter and Its Properties Chapter 1

15. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Comparison of Physical and Chemical Properties Section 2 Matter and Its Properties Chapter 1

16. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Energy and Changes in Matter Energy is always involved when physical or chemical changes occur. Energy can be in various forms. heat light Energy can be absorbed or released in a change, it is not destroyed or created. law of conservation of energy Section 2 Matter and Its Properties Chapter 1

17. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Classification of Matter Section 2 Matter and Its Properties Chapter 1

18. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Classifying Matter Section 2 Matter and Its Properties Chapter 1

19. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Classification of Matter A mixture is a blend of two or more kinds of matter, each of which retains its own identity and properties. mixed together physically can usually be separated Homogeneous mixtures are called solutions uniform in composition (salt-water solution) Heterogeneous mixtures not uniform throughout (clay-water mixture) Section 2 Matter and Its Properties Chapter 1

20. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Types of Mixtures Section 2 Matter and Its Properties Chapter 1

21. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Pure Substances A pure substance has a fixed composition. Pure substances are either compounds or elements. A pure substance differs from a mixture in the following ways: Every sample of a given pure substance has exactly the same characteristic properties. Every sample of a given pure substance has exactly the same composition. Water is always 11.2% hydrogen and 88.8% oxygen by mass. Section 2 Matter and Its Properties Chapter 1

22. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 1 The Atom: From Philosophical Idea to Scientific Theory Foundations of Atomic Theory The transformation of a substance or substances into one or more new substances is known as a chemical reaction. Law of conservation of mass: mass is neither created nor destroyed during ordinary chemical reactions or physical changes Chapter 3

23. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 1 The Atom: From Philosophical Idea to Scientific Theory Foundations of Atomic Theory, continued Law of definite proportions: a chemical compound contains the same elements in exactly the same proportions by mass regardless of the size of the sample or source of the compound Law of multiple proportions: if two or more different compounds are composed of the same two elements, then the ratio of the masses of the second element combined with a certain mass of the first element is always a ratio of small whole numbers Chapter 3

24. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Law of Conservation of Mass Section 1 The Atom: From Philosophical Idea to Scientific Theory Chapter 3

25. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Law of Multiple Proportions Section 1 The Atom: From Philosophical Idea to Scientific Theory Chapter 3

26. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 1 The Atom: From Philosophical Idea to Scientific Theory Dalton’s Atomic Theory All matter is composed of extremely small particles called atoms. Atoms of a given element are identical in size, mass, and other properties; atoms of different elements differ in size, mass, and other properties. Atoms cannot be subdivided, created, or destroyed. Chapter 3

27. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 1 The Atom: From Philosophical Idea to Scientific Theory Dalton’s Atomic Theory, continued Atoms of different elements combine in simple whole- number ratios to form chemical compounds. In chemical reactions, atoms are combined, separated, or rearranged. Chapter 3

28. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 1 The Atom: From Philosophical Idea to Scientific Theory Modern Atomic Theory Not all aspects of Dalton’s atomic theory have proven to be correct. We now know that: Chapter 3 Some important concepts remain unchanged. Atoms are divisible into even smaller particles. A given element can have atoms with different masses. All matter is composed of atoms. Atoms of any one element differ in properties from atoms of another element.

29. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 The Structure of the Atom The Structure of the Atom An atom is the smallest particle of an element that retains the chemical properties of that element. The nucleus is a very small region located at the center of an atom. The nucleus is made up of at least one positively charged particle called a proton and usually one or more neutral particles called neutrons. Chapter 3

30. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 The Structure of the Atom The Structure of the Atom, continued Surrounding the nucleus is a region occupied by negatively charged particles called electrons. Protons, neutrons, and electrons are often referred to as subatomic particles. Chapter 3

31. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Properties of Subatomic Particles Section 2 The Structure of the Atom Chapter 3

32. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 The Structure of the Atom Discovery of the Atomic Nucleus More detail of the atom’s structure was provided in 1911 by Ernest Rutherford and his associates Hans Geiger and Ernest Marsden. The results of their gold foil experiment led to the discovery of a very densely packed bundle of matter with a positive electric charge. Rutherford called this positive bundle of matter the nucleus. Chapter 3

33. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Gold Foil Experiment Section 2 The Structure of the Atom Chapter 3

34. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 The Structure of the Atom Composition of the Atomic Nucleus Except for the nucleus of the simplest type of hydrogen atom, all atomic nuclei are made of protons and neutrons. A proton has a positive charge equal in magnitude to the negative charge of an electron. Atoms are electrically neutral because they contain equal numbers of protons and electrons. A neutron is electrically neutral. Chapter 3

35. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 The Structure of the Atom Composition of the Atomic Nucleus, continued The nuclei of atoms of different elements differ in their number of protons and therefore in the amount of positive charge they possess. Thus, the number of protons determines that atom’s identity. Chapter 3

36. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 The Structure of the Atom Composition of the Atomic Nucleus, continued When two protons are extremely close to each other, there is a strong attraction between them. Chapter 3 Forces in the Nucleus The short-range proton-neutron, proton-proton, and neutron-neutron forces that hold the nuclear particles together are referred to as nuclear forces. A similar attraction exists when neutrons are very close to each other or when protons and neutrons are very close together.

37. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Counting Atoms Atomic Number Atoms of different elements have different numbers of protons. Atoms of the same element all have the same number of protons. The atomic number (Z) of an element is the number of protons of each atom of that element. Chapter 3

38. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Visual Concepts Atomic Number Chapter 3

39. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Counting Atoms Isotopes Isotopes are atoms of the same element that have different masses. The isotopes of a particular element all have the same number of protons and electrons but different numbers of neutrons. Most of the elements consist of mixtures of isotopes. Chapter 3

40. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Counting Atoms Mass Number The mass number is the total number of protons and neutrons that make up the nucleus of an isotope. Chapter 3

41. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Visual Concepts Mass Number Chapter 3

42. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Counting Atoms Designating Isotopes Hyphen notation: The mass number is written with a hyphen after the name of the element. uranium-235 Nuclear symbol: The superscript indicates the mass number and the subscript indicates the atomic number. Chapter 3

43. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Counting Atoms Designating Isotopes, continued The number of neutrons is found by subtracting the atomic number from the mass number. mass number  atomic number = number of neutrons 235 (protons + neutrons)  92 protons = 143 neutrons Nuclide is a general term for a specific isotope of an element. Chapter 3