1 / 18

Chapter 22

Chapter 22. Chemical Bonds. 22.1 Stability in Bonding. Most elements are found combined with other elements because they are not chemically stable (compounds) Noble gases are mono-atomic (6% elements) Chemical stability depends on valence electrons

fifi
Download Presentation

Chapter 22

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 22 Chemical Bonds

  2. 22.1 Stability in Bonding • Most elements are found combined with other elements because they are not chemically stable (compounds) • Noble gases are mono-atomic (6% elements) • Chemical stability depends on valence electrons • Compounds have different properties than the elements that compose it • Ex. Na, Cl, NaCl from chapter 18

  3. Writing Chemical Formulas • Chemical Formula: represents a chemical compound • Uses symbols for the elements • The subscript numbers show the ratio of ions in the compound • Formulas are like cooking recipes

  4. Write the Formula For: • Sodium chloride • Magnesium oxide • Aluminum oxide • Iron (III) oxide • Calcium fluoride • Strontium phosphate • Barium nitrate

  5. Write the Name for: • K2O • Al2O3 • Mg3N2 • CaCO3 • NaNO3 • Calculate the molecular weight for each of the above:

  6. Stable Electron Configurations • When outermost energy level is full - Atom is stable (pg. 690) • Not likely to react with other elements • Electron dot diagram – model of atom with symbol of element in the center and the valence electrons represented by dots around the symbol • Pg. 690, 691

  7. Chemical bonding occurs when elements bond with other elements or themselves to achieve stability in their valence levels • Atmospheric gases exist as molecules • Hydrogen H2 • Oxygen O2 • Nitrogen N2 • Chlorine Cl2

  8. Ionic Bonds • Metals combine with Nonmetals • Transfer of electrons to become more stable • Ions – when an atom gains or loses electrons “charged atom” • Electrons no longer equal the protons – the atom becomes charged • Draw NaCl, MgO, Al2O3

  9. Anions and Cations • Loses electrons – makes positive ion or cation – Ex. Na+ sodium ion “metals” • Gains electrons – makes negative ion or anion – add suffix -ide Ex. Cl- chloride ion “nonmetals” • Ionic bond – force that holds anions and cations together

  10. Ionic bond: formed when electrons are transferred from one atom to another • Ionization Energy: – energy required to remove an electron • Ionic Compounds: – Compounds that contain ionic bonds • Chemical Formula: – shows the elements and ratio of atoms in a compound • Crystal Lattices: – arrangement of ions in a repeating pattern – forms solid crystals

  11. 6.2 Covalent Bonding • Nonmetals combine with nonmetals • Sharing electrons to become stable • Covalent Bond – when two atoms share one pair of valence electrons – single bond • Two pairs – double bond • Three pairs – triple bond

  12. Polar Covalent Bonds • Electrons are not shared equally • Atom with greater attraction for electrons has a partial negative charge • Other atom has a partial positive charge • Ex. Water – H2O Ex. Carbon Dioxide – CO2

  13. Polyatomic Ions – a group of covalently bonded atoms with a positive or negative charge and acts as a unit • Prefix poly- means “many” • Most polyatomic ions are anions • Page 707

  14. 6.3 Naming Compounds and Writing Formulas • Chemical Formula: represents a chemical compound • Uses symbols for the elements • The subscript numbers show the ratio of ions in the compound

  15. Ionic Compounds • Write symbol of cation (metal) first followed by the symbol of the anion (nonmetal) Ex. NaCl • Use subscripts to show the ratio • Criss cross the oxidation numbers • Add the suffix “ide” to the nonmetal when naming these

  16. Covalent compounds • Name and formula describe the type and number of atoms in each molecule • Prefixes on page 709 • Use prefixes to tell how many atoms of each element Ex. N2O4 dinitrogen tetraoxide

  17. 6.4 The Structure of Metals • Metallic Bond – the attraction between a metal cation and the shared electrons that surround it • The more valence electrons in the shared pool, the stronger the metallic bond

  18. Alloys • A mixture of 2 or more elements, one of which is a metal – has properties of both metals • Copper Alloys – copper + tin = bronze copper + zinc = brass • Steel Alloys – iron + carbon = steel iron + chromium = stainless steel

More Related