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Below are a few major topics for this chapter. Note: these are NOT the only topics you should know; you are expected to master everything discussed in this chapter.

• Hint Structure of an atom: protons, neutrons, electrons
• Hint Atomic number
• Hint Electron shells and energy levels
• Hint Carbon's central role in life
• Hint Ions
• Hint Ionic bond between ions
• Hint Covalent bond: sharing of two electrons
• Hint Polar molecule: unequal sharing of electrons
• Hint Hydrogen bond: weak attraction between polar molecules
• Hint Water properties
• Hint pH scale: acids and bases