1 / 13

Chemical Bonds Ch 20

Chemical Bonds Ch 20. What makes matter different!. Sect 1 Stability in Bonding. When elements combine to form a compound, the compound has properties very different from those of the elements that make it. Ex. NaCl. Formulas.

arcelia-cruz
Download Presentation

Chemical Bonds Ch 20

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. Chemical Bonds Ch 20 What makes matter different!

  2. Sect 1 Stability in Bonding • When elements combine to form a compound, the compound has properties very different from those of the elements that make it. • Ex. NaCl

  3. Formulas • A compound ALWAYS has the same chemical formula. Ex. H2O • This tells the types and numbers of atoms making up the simplest unit of the compound. • This means the same elements in the same proportions • The same elements can combine in different ratios to form different compounds. Ex. H2O vs. H2O2

  4. The goal and purpose of bonding is stability • Using electron dot diagrams and Bohr models, we are able to see how valence electrons are arranged. • What is the goal # for outer level electrons? • When outer levels are not at this number, they try to act in a way to fill that level.

  5. Stability is Reached • When atoms gain, lose or share electrons, an attraction forms between the atoms that pulls them together to form a compound. • This attraction is called a chemical bond.

  6. Section 2 Types of Bonds Chemical Bonds hold compounds together! In this section, we will discuss Ionic and Covalent bonds.

  7. Gain or Loss of Electrons! • Chemical bonds between atoms involve the electrons. • Bonded atoms typically have a stable electron configuration. • They stabilize by forming ionic or covalent bonds.

  8. Ionic Bonds • Ionic bonds are formed by the transfer of electrons • Ionic bonds form networks instead on “molecules” . In NaCl, the ratio is one (1) Na+ ion to one (1) Cl- in a “formula unit”. • The total charge is net zero (0). Ex. MgCl2,NaCl, KI,

  9. Ionic Bonds • Ionic bonds form due to the attractive forces between the oppositely charged ions. • Ionic compounds are often crystalline solids with very high melting points. • They will also conduct electricity when dissolved in water.

  10. Covalent Bonds • Atoms that are joined by covalent bonds, share electrons • The number of covalent bonds an atom can form is dependant upon the number of electrons available for sharing. • Covalent bonds: Single – 1 pair of shared electrons Double – 2 pair of shared electrons Triple – 3 pair of shared electrons

  11. Covalent Bonds • Unequal sharing of electrons sometimes occurs in covalent bonds. • The strength of attraction of each atom to its electrons is related to the: 1. size of the atom 2. charge of the nucleus 3. the total number of electrons the atom contains

  12. Covalent Bonds • You may think of this as an “unequal sharing of electrons” • This unequal sharing has a consequence of on part of the atom having a slight negative (-) charge and another part of the atom has a slight positive (+) charge. • This is called a polar molecule. Ex.H2O

  13. Assignment • Complete questions 1-5, Section 2 review on page 614.

More Related