Covalent Bonds

1. Covalent Bonds These bonds like to share!

2. Open book to page 236 • Read the section titled Covalent Bonds • Write down three ways that Covalent Bonds are different than Ionic bonds • Be ready to share – you have 5 minutes!

3. Covalent Bonds • Covalent bonds form when two atoms share their electrons. Most things around you are held together by covalent bonds. • They usually form between atoms of nonmetals • Remember – ionic bonds usually form when metals bond with nonmetals.

4. Covalent bonds form between uncharged atoms that share electrons A Molecule is a neutral group of atoms joined by covalent bonds The simplest molecular compounds form between two covalently bonded atoms of the same element, called DIATOMIC MOLECULES – example: H2

5. What does it look like? The number of covalent bonds that a nonmetal atom can form is equal to the number of electrons needed to make a stable total of 8. Oxygen has 6 valence electrons and Hydrogen has 1. To make water the atoms must form two covalent bonds Covalent Bonds

6. Double and Triple Bonds • In order to reach the number of 8 stable valence electrons, some elements may form double or even triple bonds to make sure they get all 8. • Double bonds occur when two atoms share two pairs of electrons like in an oxygen molecules: O O • Triple bonds occur when atoms share three pairs of electrons: • N N

7. Covalent Compound = Molecular Compounds Properties of Molecular compounds: • Have low melting points (because the forces that hold them together are much weaker than the forces holding ionic compounds together, it is easier to separate the molecules) • Poor conductivity- no charged particles to conduct electricity

8. Covalent Compound ?’s • How is the bond formed in covalent compounds? • What is the other name for covalent compounds? • Which category of elements forms covalent compounds? • What are some of the properties of covalent compounds? • What is a double bond? • Why do the elements join in compounds? • How are covalent compounds different than ionic compounds?

9. Examine Figures 4 & 5 on pgs 238-239. What does each item represent? What elements make the molecules? Are these figures to scale?

10. Steps for Drawing covalent bonds • Figure out how many of each element you need(The number of electrons needed = the number of bonds that will be formed) • Draw the electron dot diagrams for each element (you may have to switch the order of the dots) • Draw circles around the bonds that are being shared O O = O2

11. Try It! Draw the electron dot diagrams for these covalent bonds • H+ H  • O + H + H • C + O + O 

12. Metallic Bonds • A metallic bond is a bond formed by the attraction between positively charged metal ions and the electrons in the metal. • Positively charged metal ions form when metal atoms lose electrons. • Metallic bonds extend throughout the metal in all directions because the outermost energy levels of the atoms overlap. • So, valence electrons are free to move throughout the metal. • Video

13. Properties of Metals • Conduct Electricity and Heat: Metallic bonding allows metals to conduct electric current. Electrons move within a wire because the valence electrons are free to move throughout the metal. • Malleability and Ductility: Because electrons move freely around metal ions, the atoms in metals can be rearranged. As a result, metals can be reshaped. • Metal objects can be bent without being broken because electrons constantly moving around and between the metal ions maintain the metallic bonds no matter how the shape of the metal changes.

14. Bond Song!