Presentation on theme: "Covalent Bonding. 1/19/12 Objective: To explore multiple covalent bonding Do Now: On a sheet of paper, write the definition of an ionic bond and a covalent."— Presentation transcript:
1/19/12 Objective: To explore multiple covalent bonding Do Now: On a sheet of paper, write the definition of an ionic bond and a covalent bond. (4 min) – For each kind of bond, give an example of a compound held together by those bonds. Do Later: Finish covalent bonding challenge puzzles
Covalent bonds Bonds in which two atoms share a pair of valence electrons. Two or more atoms held together by covalent bonds form a molecule. H H2H2 H
Octet rule revisited Recall: The purpose of bonding is to acquire a full valence shell – Ionic bonds: NaCl – Covalent bonds: H 2 O, CH 4
Double bonds Two atoms can share more than one covalent bond In a double bond, two pairs of electrons are shared
Triple bonds In a triple bond, three pairs of electrons are shared Triple bond (N 2 )
Bonding Capacity In each covalent bond, an atom – 1) shares a valence electron with its partner – 2) gets a new valence electron shared with it. Atoms need to have at least one of their own valence electrons for every covalent bond they form. Single bond
Practice problem How many valence electrons does boron have? What’s the maximum number of covalent bonds boron can form?
Practice problem Can boron ever achieve a valence octet by covalent bonding? – No!
Bonding capacity For each covalent bond an atom forms, it must have an empty space in its valence shell to receive a new electron. – Fluorine has one empty space in its valence shell, so it can only form one covalent bond
Practice problem What is the maximum number of covalent bonds the following elements can form? – Chlorine – Oxygen – Bromine – Nitrogen – Polonium
Bonding capacity The bottom line: – For each covalent bond an atom forms, it must have: 1) A valence electron to share and 2) a vacancy in its valence shell to accept a new electron.
Practice problem Fill in this table in your notes: ElementAtomic #Valence e - sVacancies in valence shell Bonding capacity Hydrogen1 Carbon6 Nitrogen7 Oxygen8 Ammonia Water Methane