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Chapter Introduction Lesson 1 Electrons and Energy Levels Lesson 2 Compounds, Chemical Formulas, and Covalent Bonds Lesson 3 Ionic and Metallic Bonds Chapter Wrap-Up. Chapter Menu. How do elements join together to form chemical bonds?. Chapter Introduction. What do you think?.

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  1. Chapter Introduction Lesson 1 Electrons and Energy Levels Lesson 2 Compounds, Chemical Formulas, and Covalent Bonds Lesson 3Ionic and Metallic Bonds Chapter Wrap-Up Chapter Menu

  2. How do elements join together to form chemical bonds? Chapter Introduction

  3. What do you think? Before you begin, decide if you agree or disagree with each of these statements. As you view this presentation, see if you change your mind about any of the statements. Chapter Introduction

  4. 1. Elements rarely exist in pure form. Instead, combinations of elements make up most of the matter around you. 2. Chemical bonds that form between atoms involve electrons. Do you agree or disagree? Chapter Introduction

  5. 3.The atoms in a water molecule are more chemically stable than they would be as individual atoms. 4. Many substances dissolve easily in water because opposite ends of a water molecule have opposite charges. Do you agree or disagree? Chapter Introduction

  6. 5. Losing valence electrons can make some atoms more chemically stable. 6. Metals are good electrical conductors because they tend to hold onto their valence electrons very tightly. Do you agree or disagree? Chapter Introduction

  7. Electrons and Energy Levels • How is an electron’s energy related to its distance from the nucleus? • Why do atoms gain, lose, or share electrons? Lesson 1 Reading Guide - KC

  8. Electrons and Energy Levels • chemical bond • valence electron • electron dot diagram Lesson 1 Reading Guide - Vocab

  9. The Periodic Table • Elements on the periodic table are organized in periods (rows) and groups (columns). • The periodic table lists elements in order of atomic number, which increases from left to right as you move across a period. Lesson 1-1

  10. The three main regions of elements on the periodic table classify elements as metals, nonmetals, or metalloids. Lesson 1-1

  11. The Periodic Table (cont.) • Except for hydrogen, elements on the left side of the table are metals. • Nonmetals are on the right side of the table. • Metalloids form the narrow stair-step region between metals and nonmetals. Lesson 1-1

  12. Atoms Bond • A chemical bond is a force that holds two or more atoms together in a compound. • Atoms contain protons, neutrons, and electrons. • Each proton has a positive charge; each neutron has no charge; and each electron has a negative charge. Lesson 1-2

  13. Protons and neutrons are in an atom’s nucleus. Electrons move around the nucleus. Lesson 1-2

  14. Atoms Bond(cont.) • The atomic number of an element is the number of protons in each atom of that element. • An electron moves around the nucleus at a distance that corresponds to its amount of energy. Lesson 1-2

  15. Atoms Bond(cont.) • Areas of space in which electrons move around the nucleus are called energy levels. • Electrons closest to the nucleus have the least amount of energy. Electrons farthest from the nucleus have the greatest amount of energy. Lesson 1-2

  16. Electron Energy Levels Lesson 1-2

  17. Atoms Bond(cont.) How is an electron’s energy related to its position in an atom? Lesson 1-2

  18. Atoms Bond(cont.) • The attraction between the positive nucleus of one atom and the negative electrons of another atom is what creates a chemical bond. • A valence electron is an outermost electron of an atom that participates in chemical bonding. Lesson 1-2

  19. Atoms Bond(cont.) The number of valence electrons in each atom of an element can help determine the type and number of bonds that an atom can form. valence from Latin valentia, means “strength, capacity” Lesson 1-2

  20. The periodic table can tell you how many valence electrons an atom has. Lesson 1-2

  21. Atoms Bond(cont.) In 1916 an American chemist named Gilbert Lewis developed the electron dot diagram, a model that represents valence electrons in an atom as dots around the element’s chemical symbol. Lesson 1-2

  22. Lesson 1-3

  23. Atoms Bond(cont.) • Atoms with eight valence electrons are chemically stable and do not easily react with other atoms. • Atoms that have between one and seven valence electrons are reactive or chemically unstable and easily bond with other atoms to form chemically stable compounds. Lesson 1-2

  24. Atoms Bond(cont.) • The elements in group 18 are called noble gases. • With the exception of helium, noble gases have eight valence electrons and are chemically stable. Lesson 1-2

  25. Atoms gain, lose, or share valence electrons and become chemically stable. Lesson 1-2

  26. Atoms Bond(cont.) Why do atoms gain, lose, or share electrons? Lesson 1-2

  27. Electrons are less strongly attracted to a nucleus the farther they are from it, similar to the way a magnet attracts a paper clip. Lesson 1 - VS

  28. Electrons in atoms are in energy levels around the nucleus. Valence electrons are involved in chemical bonding. Lesson 1 - VS

  29. All noble gases, except He, have four pairs of dots in their electron dot diagrams. Noble gases are chemically stable. Lesson 1 - VS

  30. Where on the periodic table are nonmetals located? A. the left side B. the right side C. the middle D. all of the above Lesson 1 – LR1

  31. Which term refers to areas of space in which electrons move around the nucleus? A. electron dot diagram B. periodic table C. neutron D. energy levels Lesson 1 – LR2

  32. All of the elements in group 18 are called what? A. metalloids B. valence electrons C. noble gases D. metals Lesson 1 – LR3

  33. 1. Elements rarely exist in pure form. Instead, combinations of elements make up most of the matter around you. 2. Chemical bonds that form between atoms involve electrons. Do you agree or disagree? Lesson 1 - Now

  34. Compounds, Chemical Formulas, and Covalent Bonds • How do elements differ from the compounds they form? • What are some common properties of a covalent compound? • Why is water a polar compound? Lesson 2 Reading Guide - KC

  35. Compounds, Chemical Formulas, and Covalent Bonds • covalent bond • molecule • polar molecule • chemical formula Lesson 2 Reading Guide - Vocab

  36. From Elements to Compounds • Compounds are chemical combinations of different types of atoms. • Chemical bonds join atoms together. Lesson 2-1

  37. From Elements to Compounds(cont.) bond Science Use a force that holds atoms together in a compound Common Use a close personal relationship between two people Lesson 2-1

  38. From Elements to Compounds(cont.) How is a compound different from the elements that make it up? Lesson 2-1

  39. Covalent Bonds—Electron Sharing • A covalent bond is a chemical bond formed when two atoms share one or more pairs of valence electrons. • A compound formed from many covalent bonds is called a covalent compound. Lesson 2-2

  40. Atoms with less than eight valence electrons become chemically stable by forming a chemical bond. Lesson 2-2

  41. Covalent Bonds—Electron Sharing (cont.) • A single covalent bond exists when two atoms share one pair of valence electrons. • A double covalent bond exists when two atoms share two pairs of valence electrons • A triple covalent bond exists when two atoms share three pairs of valence electrons. Lesson 2-2

  42. The more valence electrons that two atoms share, the stronger the covalent bond is between the atoms. Lesson 2-2

  43. Covalent Compounds • When two or more atoms share valence electrons, they form a stable covalent compound. • Covalent compounds usually have low melting points and low boiling points. • They are usually gases or liquids at room temperature, but they can also be solids. • Covalent compounds are poor conductors of thermal energy and electricity. Lesson 2-3

  44. Covalent Compounds(cont.) What are some common properties of covalent compounds? Lesson 2-3

  45. Covalent Compounds(cont.) • A molecule is a group of atoms held together by covalent bonding that acts as an independent unit. • A molecule that has a partial positive end and a partial negative end because of unequal sharing of electrons is a polar molecule. Lesson 2-3

  46. Covalent Compounds(cont.) polar from Latin polus, means “pole” Lesson 2-3

  47. Atoms of a polar molecule share their valence electrons unequally. Lesson 2-4

  48. Atoms of a nonpolar molecule share their valence electrons equally. Lesson 2-4

  49. Covalent Compounds(cont.) Why is water a polar compound? Lesson 2-4

  50. Covalent Compounds(cont.) • A chemical formula is a group of chemical symbols and numbers that represent the elements and the number of atoms of each element that make up a compound. • A chemical formula describes the types of atoms in a compound or a molecule, but it does not explain the shape or appearance of the molecule. Lesson 2-3

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