Concept: Types of Chemical Bonds Chapter 6 Concept: Types of Chemical Bonds

What is chemical bonding? Occurs when there is a strong attraction between the valence electrons of one atom and the nucleus of another atom Formed by rearranging electrons Atoms have relatively high potential energy as independent particles; but, tend to move toward low potential energy The way electrons are distributed will determine the type of bond Most chemical bonds are partly ionic and partly covalent

What is chemical bonding? 3 types of Chemical Bonding Ionic Covalent Metallic Ionic and covalent are the two main types of bonding!!!!

LEQ: What are characteristics of ionic bonding? Between metal and nonmetal Electrical attraction (opposite charges hold compounds together). Smallest particle is an ion Solid at room temperature; but, brittle Crystalline lattice structure (repeating patterns of ions)

LEQ: What are characteristics of ionic bonding? Stronger than covalent bonds Formula unit Makes atoms more stable Lowers potential energy High melting and boiling points Good conductors of electricity (in molten state)

LEQ: What are characteristics of ionic bonding? Ionic bonds (giving or taking of electrons) Cations + charge Lose/give up electrons metals Anions (-) charge Gain electrons nonmetals

LEQ: What are characteristics of ionic bonding? Terms to know Ionic compound Compound composed of +/- ions that combine so that they are equal Formula Unit Simplest ratio of (+) ions to (–) ions represented by the formula

LEQ: What are characteristics of covalent bonding? 2 nonmetals share electrons so that both have 8 valence electrons (except H) Forms molecules Liquid or gas at room temperature Illustrated with Lewis Dot Can be polar or non-polar Not as strong as/weaker than ionic bonds Makes atoms more stable by lowering potential energy Low melting and boiling points

LEQ: What are characteristics of covalent bonding? Non-polar covalent Electrons shared equally No charge created Occurs between 2 identical atoms 7 diatomic molecules (HOClBrFIN)

LEQ: What are characteristics of covalent bonding? Polar Covalent Electrons not shared equally (tug-of-war) Electrons spend more time around the more electronegative atom Slight charges created (-) charge around the more electronegative atom. Example: water, HCl (hydrochloric acid)

LEQ: What are characteristics of covalent bonding? Terms to Know Molecule A neutral group of atoms held together by a covalent bond Molecular compound Another name for covalent compound Chemical formula # of atoms of each element in a compound represented by using symbols and subscripts

LEQ: What are characteristics of covalent bonding? Terms to Know Molecular Formula Types and numbers of atoms in a single molecule Used for covalent compounds Example: H2O

LEQ: What are characteristics of covalent bonding? 1. To lower potential energy by making the substance more stable Attract/repel each other until the distance between the atoms is reached where the repulsion between the like charges equal the attraction of the opposite charges Atoms have relatively high potential energy as independent particles; but, tend to move toward low potential energy

LEQ: What are characteristics of covalent bonding? 2. To form octet Octet rule – atoms tend to form compounds (by gaining, losing, or sharing electrons) so that the highest energy level is full (8 electrons in s & p orbitals) How many more electrons does nitrogen need to satisfy the octet rule if its electron configuration is 1s22s22p3 ?

LEQ: What are characteristics of covalent bonding? Exceptions to octet rule: Hydrogen – surrounded up to 2 electrons Boron – up to 6 electrons Fluorine, oxygen, and chlorine – more than 8 electrons because they have high electronegativities

LEQ: What are characteristics of ionic and covalent bonding? Differences in Electronegativity 0-0.3 (0%-5%)Non-polar covalent Diatomic molecules 0.3-1.7 (5%-50%)polar-covalent HCl 1.7-3.3 (50% - 100%)ionic NaCl

Lewis Dot Structures Uses electron dot to illustrate what a molecule looks like Electron dot notation Only shows valence electrons Symbol of element stands for nucleus and all inner shell electrons Lewis Dot can show single, double, and triple bonds If carbon is present, use as central atom. If not, use the least electronegative atom as the central atom. NEVER use hydrogen as central atom.

Lewis Dot Structures Examples: IBr O2 CH3Br OF2 HCL CF4

What are unique characteristics of Polyatomic Ions? A group of covalently bonded atoms that have a charge representing extra electrons PO43- , NH4+ Negative – excess of electrons Positive – shortage of electrons Has molecular and ionic characteristics

Metallic Bonding Chemical bonding that results from an attractions between metal atoms and the surrounding electrons The ions are capable of sliding past one another Creates the characteristics of being malleable, ductile, and shiny.