IONIC BONDS Chapter 5 Section 2

Ions Atoms are stable when their outermost shell is full! Sometimes it is easier to lose electrons rather than gain. Other times it is easier to gain! If an atom has 6 valence electrons, it needs ___ more to be stable. If an atom has 7 valence electrons, it needs ___ more to be stable. If an atom has 2 valence electrons, how will it become stable?

Ions Ion: An atom with a positive or negative charge. When an atoms loses an electron, it has a _____ charge. Called a: When an atom gains an electron, it has a _____ charge.

Lewis Dot Structures (Also called Electron Dot Diagrams) Represents # of valence electrons. Can easily see how many electrons need to be gained or lost in order to be “happy” Electron Dot Diagrams will be how we “draw” chemical bonds.

Ionic Bonds Ionic bonds: Form as a result of the attraction between positive and negative ions.

The Atoms BEFORE The Atoms AFTER Ionic bonds usually form between a Metal and a Nonmetal! - Na gives Cl its one valence electron so that its next level will be full with 8. - Cl gains Na’s electron so its outer shell is full with 8. - Since Na lost an electron it becomes an + ion - Since Cl gained an electron it becomes - ion - Opposites attract and the positive Na ion “sticks” to the negative Cl

Let’s look at this example: Ionic bonds usually form between a Metal and a Nonmetal! The metal is ____________ and the nonmetal is ____________. ____ gives ____ its one valence electron so that its final level will be full. ____ gains ____’s electron so its outer shell is full. The positive ion: The negative ion: Opposites attract, so:

Chemical Formulas MgCl2 C6H1206 CaCO3 Combination of symbols that shows the ratio of elements in a compound. When Ionic compounds form, they balance the charges. Always write the Positive ion in front of the negative ion Subscript: the # that tells you the ratio of elements in a compound. For Example: MgCl2 C6H1206 CaCO3

Properties of Ionic Compounds Ionic compounds are hard, brittle solids with high melting points. When melted or dissolved in water, they conduct an electric current. Ionic compounds form an orderly, 3-D pattern = crystal