Bonding and Chemical Equations

Valance Electrons Electrons in the outer most orbit of an atom. Available for elements to combine with other elements to create molecules and compounds. Group 1 = 1 valance electron Can share or donate this electron easily. Group 2 = 2 valance electrons Can share or donate these electrons.

Valence Electrons Group 16 = 6 valance electrons Can accept 2 electrons. Group 17 = 7 valance electrons Can accept 1 electron.

Valance Electrons

Nobel Gases Group 18 – Nobel Gases Outer orbit is completely filled with electrons. Elements are happiest or stable when their outer orbits are completely full! DO NOT bond with any other element to create molecules or compounds!

Bonding An element’s goal is to reach the stable level, a full outer orbit. To do this they bond with other elements based on how many electrons are needed to become stable. Group 1 1 Valence electron – looking to bond with an element needing 1 or 2 electrons: Group 16 – needs 2 Group 17 – needs 1

Bonding Group 1 & Group 17 H:F = Hydrogen Fluoride Na:Cl = Sodium Chloride Li:F = Lithium Fluoride

Bonding Group 1 & Group 16 H:O:H = Water Li:S:Li = Lithium Sulfide Na:O:Na = Sodium Oxide Na:O:H = Sodium Hydroxide

Bonding Group 2 & Group 16 Be:O = Beryllium Oxide Mg:S = Magnesium Sulfide

Counting Atoms Allows you to see the number of each element involved in a reaction. All reactants must be present in the product in the same quantities!

Counting Atoms Identify how many atoms of each element are present in each molecule or compound. Calcium Carbonate - CaCO3 Calcium (Ca) - Carbon (C) - Oxygen (O) - Magnesium Hydroxide – Mg(OH)2 Magnesium (Mg) - Oxygen (O) – Hydrogen (H) - 1 1 3 1 1 X 2 = 2 1 X 2 = 2

Chemical Equations The Law of Conservation of Mass states that matter can’t be created or destroyed. What you have present in the reactants of an equations MUST be present in the products. Chemical equations must have equal numbers of atoms on the left of the equation (reactants) as it does the right (products). H2 + O = H2O __Mg + O2 = __MgO 2 2

Chemical Equations __P + __O2 = P4O10 N2 + __H2 = __NH3 Balance the following equations: __P + __O2 = P4O10 N2 + __H2 = __NH3 __ Al + __ O2 = Al2O3 4 5 3 2 4 3

Chemical Equations Zn + O2 = ZnO P4 + H2 = PH3 H2O2 = H2O + O2 2 2 6 4 Balance the following equations: Zn + O2 = ZnO P4 + H2 = PH3 H2O2 = H2O + O2 2 2 6 4 2