22.2 Notes – Types of Bonds

Objective  Describe ionic and covalent bonds.  Identify the particles produced by ionic bonding and by covalent bonding.

Ion  An atom that has lost or gained electrons A charged particle because it has more or fewer electrons than protons  Atoms lose or gain to meet a standard—a stable energy level

How bonds form  The positive and negative charges are not balanced on their own  It is the electric forces between oppositely charged particles that hold compounds together

A Bond Forms - KI  A neutral atom of potassium has one electron in its outer level Not a stable outer energy level  Potassium often forms compounds with halogens Alkalis (Group 1) often form compounds with Halogens (Group 17 / 7A)

 Ion = K + Loses an electron (drops one energy level), becomes positively charged One less electron in the atom than protons in the nucleus The 1+ charge is shown as a superscript written after the element’s symbol to indicate its charge

 Iodine atom also undergoes a change Iodine has 7 electrons in its outer energy level Iodine atom wants to gain an electron to fill its outer energy level No longer neutral because it has gained an extra negative particle  Has a charge of – 1 and is called a iodide ion, written as I -

Potassium iodide

 Cation = positive ion Loses electrons  Anion = negative ion Gains electrons

Ionic Bonds  When ions attract due to their opposite charges  In an ionic bond a transfer of one or more electrons takes place and large amounts of energy are released If an element loses electrons, one or more elements must gain an equal number of electrons to maintain the neutral charge

Formation of Ionic Bond  Magnesium reacts with chlorine  Magnesium atom loses 2 electrons and becomes a positively charged ion, Mg 2+  Two chlorine atoms gain one electron each and become negatively charged ions, Cl -

Ionic Bonds  Zero net charge = Neutral compound Positive charge balances with negative charge  Metal + nonmetal  Elements on opposite sides of periodic table

In-class Assignment/homework  Get out learning target inventory and under a column yourself on objectives #1-5 and Muddiest Point  22.1 & 22.2 Directed reading WKT