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

Transcription

1 Biology 1 of 40

2 2 of 40

3 Atoms Atoms The study of chemistry begins with the basic unit of matter, the atom. 3 of 40

4 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. 4 of 40

5 Atoms The subatomic particles that make up atoms are protons neutrons electrons 5 of 40

6 Atoms The subatomic particles in a helium atom. 6 of 40

7 Elements and Isotopes 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. 7 of 40

8 Elements and Isotopes The number of protons in an atom of an element is the element's atomic number. What else does the atomic number equal? Commonly found in living organisms: 8 of 40

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

10 Nonradioactive carbon- 12 Nonradioactive carbon- 13 Radioactive carbon electrons 6 protons 6 neutrons 6 electrons 6 protons 7 neutrons 6 electrons 6 protons 8 neutrons 10 of 40

11 Elements and Isotopes Because they have the same number of electrons, all isotopes of an element have the same chemical properties. 11 of 40

12 Elements and Isotopes Radioactive Isotopes Some isotopes are radioactive, meaning that their nuclei are unstable and break down at a constant rate over time 12 of 40

13 Elements and Isotopes Radioactive isotopes can be used: to determine the ages of rocks and fossils. to treat cancer. to kill bacteria that cause food to spoil. as labels or tracers to follow the movement of substances within an organism. 13 of 40

14 Chemical Compounds Chemical Compounds A chemical compound is a substance formed by the chemical combination of two or more elements in definite proportions. 14 of 40

15 Chemical Compounds Chemical Formula Water = H2O Table Salt = NaCl Hydrochloric Acid = HCl Glucose = C6H12O6 15 of 40

16 Chemical Bonds Chemical Bonds The atoms in compounds are held together by chemical bonds. The electrons that are available to form bonds are called valence electrons. 16 of 40

17 Chemical Bonds The main types of chemical bonds are: ionic bonds covalent bonds 17 of 40

18 Ionic Bonds 2-1 The Nature of Matter Chemical 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. 18 of 40

19 Chemical Bonds Sodium atom (Na) Sodium ion (Cl - ) Pg.38 in book Protons +11 Electrons - 11 Charge 0 Protons +17 Electrons - 18 Charge of 40

20 Chemical Bonds Covalent Bonds Sometimes electrons are shared by atoms instead of being transferred. 20 of 40

21 Chemical Bonds A covalent bond forms when electrons are shared between atoms. single covalent bond 2 electrons shared double bond 4 electrons shared triple bond 6 electrons shared 21 of 40

22 Chemical Bonds The structure that results when atoms are joined together by covalent bonds is called a molecule. 22 of 40

23 Chemical Bonds Van der Waals Forces When molecules are close together, a slight attraction can develop between the oppositely charged regions of nearby molecules. Forces of attraction between molecules. Hold large molecules together. Allow geckos to balance the pull of gravity. 23 of 40

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25 These synthetic Carbon nanotubes make a glue 10X stickier than a gecko s foot 25 of 40

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27 2-1 Continue to: - or - Click to Launch: 27 of 40 End Show

28 2-1 The particles that move around the nucleus of an atom are called a. neutrons. b. protons. c. electrons. d. isotopes. 28 of 40

29 2-1 The atomic number of a carbon atom is 6. How many neutrons does the isotope carbon-14 have? a. 6 b. 8 c. 12 d of 40

30 2-1 Which of the following statements about the three isotopes of carbon is true? a. They are all radioactive. b. They have different numbers of electrons. c. They have the same chemical properties but differ in atomic mass. d. They have the same number of protons and neutrons. 30 of 40

31 2-1 A chemical compound consists of a. Electrons mixed with neutrons. b. two or more elements combined in a definite proportion. c. two or more protons combined in any proportion. d. at least three elements combined by ionic or covalent bonds. 31 of 40

32 2-1 Van der Waals forces are the result of a. unequal sharing of electrons. b. ionic bonds. c. the bonding of different isotopes. d. the chemical combination of sodium and chlorine. 32 of 40

33 END OF SECTION