Chemical Bonding

Why do Bonds Form? Atoms want to have full outer shells When atoms bond, each atom has a full energy level of valence electrons (just like the noble gases)

Types of Bonds Two main types of bonding Ionic Covalent

What are some things you remember about chemical bonding?

Ionic bonding Which group(s) do you think will lose electrons? Will this make them positive or negative? Which group(s) do you think will gain electrons? Will this make them positive or negative?

Ionic Bonds Atoms of metals tend to lose electrons to form positive ions (cations) Nonmetals tend to gain electrons and form negative ions (anions) Ionic bonds form when one atom gives electron(s) to another atom

Characteristics of Ionic Compounds Conduct electricity when melted or dissolved in water High melting and boiling points Strongest bonds!

Oxidation Numbers The oxidation number is equal to the charge of an atom after it has gained or lost electron(s) Ex: NaCl

Practice Calcium + Oxygen Magnesium + Chlorine Aluminum + Sulfur Ag+2 + Cl Draw Lewis dot structure Oxidation numbers Show electron transfer Write the formula

Element Speed Dating 1. Name 2. “Profile Picture” (Lewis Dot Model) 3. What do you have to bring to a stable relationship? (Number of valence electrons) Directions: In each rotation, Write the name of your element partner. If you can form a bond, identify it as ionic or covalent and write the resulting formula. If not, write “no bond.” 4. What do you want out of a relationship? (Will you lose or gain electrons? How many?)

Use the electronegativity values listed below to answer the following questions. Element X = 3.44 Element Y = 0 Element Z = 0.82 Which element is most likely a metal? Which elements are nonmetals? Which two elements would likely be able to form an ionic bond? In the ionic bond, identify the cation and the anion.

Before You Leave… What is one thing you learned today? What is one question you still have? What is one thing you already know (or can predict) about covalent bonding?

Covalent Bonds Formed by atoms sharing electrons Usually formed between nonmetals Weaker than ionic bonds

Characteristics of Covalent Bonds Low melting and boiling points Do not conduct electricity Can be solid, liquid, or gas Can share more than one pair of electrons Double or triple bond

Covalent Practice Chlorine and Chlorine Hydrogen and Oxygen Oxygen and Oxygen Carbon and Selenium Nitrogen and Sulfur

Ionic or Covalent? PH3 LiCl A diatomic molecule Compound A melts at a lower temperature than Compound B. Compound X does not conduct electricity.