Copyright Pearson Prentice Hall Biology Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall CHEMISTRY Essential Question: What is the difference between an atom, an element, and a compound? Photo Credit: © John Conrad/CORBIS Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall Atoms Atoms The study of chemistry begins with the basic unit of matter, the atom. Copyright Pearson Prentice Hall
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. Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall Atoms The subatomic particles that make up atoms are protons neutrons electrons Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall Atoms The subatomic particles in a helium atom. Helium atoms contain protons, neutrons, and electrons. The positively charged protons and uncharged neutrons are bound together in the dense nucleus, while the negatively charged electrons move in the space around the nucleus. Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall 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. Copyright Pearson Prentice Hall
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: Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall Chemical Compounds Chemical Compounds A chemical compound is a substance formed by the chemical combination of two or more elements in definite proportions. Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall Chemical Compounds Chemical Formula Water H2O Table Salt NaCl Hydrochloric Acid HCl Glucose C6H12O6 Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall 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. Copyright Pearson Prentice Hall
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. Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall Chemical Bonds Sodium atom (Na) Sodium ion (Cl-) Sodium ion (Na+) Sodium atom (Cl) Protons +11 Electrons - 11 Charge 0 Protons +11 Electrons - 10 Charge +1 Protons +17 Electrons - 17 Charge 0 Protons +17 Electrons - 18 Charge -1 The chemical bond in which electrons are transferred from one atom to another is called an ionic bond. The compound sodium chloride forms when sodium loses its valence electron to chlorine. Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall Chemical Bonds Covalent Bonds Sometimes electrons are shared by atoms instead of being transferred. Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall Chemical Bonds A covalent bond forms when electrons are shared between atoms. single covalent bond double bond triple bond Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall Chemical Bonds The structure that results when atoms are joined together by covalent bonds is called a molecule. Copyright Pearson Prentice Hall
The Chemistry of Carbon Organic chemistry is the study of all compounds that contain bonds between carbon atoms. Copyright Pearson Prentice Hall
Copyright Pearson Prentice Hall Four groups of organic compounds found in living things are: carbohydrates lipids nucleic acids proteins Macromolecules Copyright Pearson Prentice Hall