Date: October 13, 2015 Aim #15: What role do electrons play in chemical bonding? HW: Worksheet- Counting Valence Electrons (back) Quiz (Inorganic Chemistry)- Wednesday 10/21 & Thursday 10/22 (day of double period) Do Now: Warm-Up Notebook Date Title of Activity Page # 10/10 Chemistry Review 30

What determines an atom’s reactivity? Electrons 2nd energy level (8 electrons max) 1st energy level (2 electrons max) 1st energy level (2 electrons max) Usually it is the electrons in the highest energy level of an atom that determine how that atom reacts

Valence Electrons The number of electrons present in the highest energy level. How many valence electrons does this atom have? 1 The valence electrons determine the kinds and number of bonds atoms can form.

C O Lewis Dot Structures Dots are used to represent electrons in the outermost shell (valence electrons). Dots are placed around the symbol. Let’s look at Carbon: Let’s look at Oxygen: C O Lewis Structures help us determine how many bonds an atom can form.

Lewis Dot Structure Rules: Determine the number of electrons in the outer (valence shell). 2) Place a dot at the 12:00 position and continue in a clockwise direction. Do not form “electron pairs” until you have completed a circuit.

What are chemical bonds? Chemical bonds join atoms together Reactions between atoms result in filled outer energy levels. This makes the atoms stable.

How many bonds can an atom form? 4 2 1 Rule: Atoms can form bonds up to the number of non-paired electrons in its valence energy level.

Lewis Dot Structures & Bonding

Aim #15: What role do electrons play in chemical bonding? Date: October 14, 2015 Aim #15: What role do electrons play in chemical bonding? HW: Worksheet- How will they bond? Textbook Guided Reading 2-2 due Thursday Quiz (Inorganic Chemistry)- Wednesday 10/21 & Thursday 10/22 (day of double period) Do Now: Warm-Up Notebook Date Title of Activity Page # 10/14 31

The metals are blue and nonmetals are yellow.

Types of Bonds: Covalent Bonds Covalent Bond forms when two atoms share electrons. **Notice how the energy levels are no longer partially filled.

Covalent Bonds: Sharing of electrons between two non-metals In the diagram, two hydrogen atoms are bonded by a single covalent bond. The two atoms each share a pair of electrons.

Review: Number of Bonds an Atom Can Form the number of bonds that an atom can form correlates to the number of electrons that is needed to have a full outer shell H can form 1 covalent bond O can form 2 N can form 3 C can form 4

Covalent Bonding Sharing

Double or triple bonds: Double Bond- atoms share two pairs of electrons between them Triple Bond- atoms share three pairs of electrons between them

Short hand Method for Drawing Covalent Bonds Straight lines can be used to represent a covalent bond between two atoms. A single line is used to represent a single bond Two lines are used to represent a double bond Three lines represent a triple bond. Some single, double, and triple bonds are shown below

Types of Bonds: Ionic Bonds An ionic bond occurs when an atom transfers an electron to another atom. Na loses an electron and becomes a positive ion. Cl gains an electron and becomes a negative ion.

Activity: Diagram the electron shell configuration for Sodium and Chloride What would have to happen for them to both have a full outer shell? What Nobel Gas matches these configurations?

Ionic bonds: transfer of electrons between a metal and a non-metal Example: Na+Cl- Metals Lose (e-) and become positive ions (Cations) Nonmetals gain (e-)and become negative ions (Anions) The ions (atom with a charge) in a compound are attracted to each other due to opposite charges.

More Ionic Bonds * * * * * H F * * * * * Electron Is transferred H becomes positive charged (H+) F becomes negatively charged (F-) **Notice how the energy levels are no longer partially filled.

Oxidation & Reduction (REDOX)

Brain Pop- Chemical Bonds https://www.brainpop.com/science/matterandchemi stry/chemicalbonds/