1. End Show Slide 1 of 40 Copyright Pearson Prentice Hall Biology

2. End Show Slide 2 of 40 Copyright Pearson Prentice Hall 2-1 The Nature of Matter

3. End Show 2-1 The Nature of Matter Slide 3 of 40 Copyright Pearson Prentice Hall Atoms The study of chemistry begins with the basic unit of matter, the atom.

4. End Show 2-1 The Nature of Matter Slide 4 of 40 Copyright Pearson Prentice Hall Atoms Placed side by side, 100 million atoms would make a row only about 1 centimeter long. Atoms contain subatomic particles that are even smaller.

5. End Show 2-1 The Nature of Matter Slide 5 of 40 Copyright Pearson Prentice Hall Atoms The subatomic particles that make up atoms are protons neutrons electrons

6. End Show 2-1 The Nature of Matter Slide 6 of 40 Copyright Pearson Prentice Hall Atoms The subatomic particles in a helium atom.

7. End Show 2-1 The Nature of Matter Slide 7 of 40 Copyright Pearson Prentice Hall Elements and Isotopes A chemical element is a pure substance that consists entirely of one type of atom. C stands for carbon. Na stands for sodium.

8. End Show 2-1 The Nature of Matter Slide 8 of 40 Copyright Pearson Prentice Hall Elements and Isotopes The number of protons in an atom of an element is the element's atomic number. Commonly found in living organisms:

9. End Show 2-1 The Nature of Matter Slide 9 of 40 Copyright Pearson Prentice Hall Elements and Isotopes Isotopes Atoms of the same element that differ in the number of neutrons they contain are known as isotopes.

10. End Show 2-1 The Nature of Matter Slide 10 of 40 Copyright Pearson Prentice Hall Elements and Isotopes Because they have the same number of electrons, all isotopes of an element have the same chemical properties.

11. End Show 2-1 The Nature of Matter Slide 11 of 40 Copyright Pearson Prentice Hall Elements and Isotopes Isotopes of Carbon 6 electrons 6 protons 8 neutrons

12. End Show 2-1 The Nature of Matter Slide 12 of 40 Copyright Pearson Prentice Hall Chemical Compounds A chemical compound is a substance formed by the chemical combination of two or more elements in definite proportions.

13. End Show 2-1 The Nature of Matter Slide 13 of 40 Copyright Pearson Prentice Hall Chemical Compounds Chemical Formula Water Table Salt Hydrochloric Acid Glucose

14. End Show 2-1 The Nature of Matter Slide 14 of 40 Copyright Pearson Prentice Hall Chemical Bonds The atoms in compounds are held together by chemical bonds. The electrons that are available to form bonds are called valence electrons.

15. End Show 2-1 The Nature of Matter Slide 15 of 40 Copyright Pearson Prentice Hall Chemical Bonds The main types of chemical bonds are: ionic bonds covalent bonds

16. End Show 2-1 The Nature of Matter Slide 16 of 40 Copyright Pearson Prentice Hall Chemical Bonds Ionic Bonds An ionic bond is formed when one or more electrons are transferred from one atom to another. These positively and negatively charged atoms are known as ions.

17. End Show 2-1 The Nature of Matter Slide 17 of 40 Copyright Pearson Prentice Hall Chemical Bonds Protons +17 Electrons - 18 Charge -1 Protons +11 Electrons - 11 Charge 0 Protons +11 Electrons - 10 Charge +1 Protons +17 Electrons - 17 Charge 0 Sodium ion (Cl - ) Sodium atom (Na) Sodium atom (Cl) Sodium ion (Na+)

18. End Show 2-1 The Nature of Matter Slide 18 of 40 Copyright Pearson Prentice Hall Chemical Bonds Covalent Bonds Sometimes electrons are shared by atoms instead of being transferred.

19. End Show 2-1 The Nature of Matter Slide 19 of 40 Copyright Pearson Prentice Hall Chemical Bonds A covalent bond forms when electrons are shared between atoms. single covalent bond double bond triple bond

20. End Show 2-1 The Nature of Matter Slide 20 of 40 Copyright Pearson Prentice Hall Chemical Bonds The structure that results when atoms are joined together by covalent bonds is called a molecule.

21. End Show 2-1 The Nature of Matter Slide 21 of 40 Copyright Pearson Prentice Hall Chemical Bonds Van der Waals Forces When molecules are close together, a slight attraction can develop between the oppositely charged regions of nearby molecules. van der Waals forces

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