J OURNAL #48 Draw Lewis Dot structures for the following elements: 1. Phosphorus 2. Chlorine 3. Boron 4. Sulfur

T ODAY WE WILL IDENTIFY AND DESCRIBE THE TYPES OF CHEMICAL BONDING

T YPES OF C HEMICAL B ONDING A chemical bond is a mutual electrical attraction between the nuclei and valence electrons of different atoms that binds the atoms together. 2 types: Ionic - transfer of electrons between cations and anions Covalent - sharing of electron pairs between 2 atoms. In a purely covalent bond, the shared electrons are “owned” equally by the 2 bonded atoms

I ONIC OR C OVALENT ? Bonding between atoms of different elements is rarely purely ionic or purely covalent. It usually falls between these 2 extremes. Remember… electronegativity is a measure of an atom’s ability to attract electrons. Bonding between 2 atoms of the same element is completely covalent. Nonpolar-covalent bond - bond in which the bonding electrons are shared equally by the bonded atoms, resulting in a balanced distribution of electrical charge. Example: Hydrogen gas

I ONIC OR C OVALENT ? Polar covalent bond - is a covalent bond in which the bonded atoms have an unequal attraction for the shared electrons. Example: water Bonds with electronegatively difference of 0 to 0.3 are generally considered nonpolar In bonds with significantly different electronegativities, the bond is generally considered polar.

L ET ’ S P RACTICE : If you look on page 161, your book provides the electronegativities of the different elements. Sulfur has an electronegativity of 2.5. The electronegativities of hydroge, cesium and chlorine are 2.1, 0.7 and 3.0 Determine they type of bond for the pairs below: Bond between Sulfur and Hydrogen Bond between Sulfur Cesium Bond between Sulfur and Chlorine

L ET ’ S P RACTICE : What is the difference between covalent and ionic bonding? How is electronegatively used in determining ionic or covalent bonding? What types of bonding would be expected between the following atoms? Li and F Cu and S I and Br

L ET ’ S P RACTICE : Use Lewis dot structures to show bonding between elements: Hydrogen- Hydrogen Sodium- Chlorine Fluorine- Fluorine Hydrogen- Chlorine

D RAW L EWIS D OT S TRUCTURES FOR COMPOUNDS AND DETERMINE EACH ATOM TO BE A CATION OR ANION : 1. Calcium chloride (Ca 2 Cl) 1. Lithium oxide (Li 2 O) 2. Methane (CH 4 ) 3. Carbon dioxide (CO 2 )