Forming Compounds Science 10 Ms. McGrath

Important terms You should be familiar with the following terms: ionic compound ion

Forming Compounds The goal of every atom is to become stable (full valence shell) Ex. : Na +, Mg 2+, Al 3+  Have the same number of electrons as the noble gas neon

Ions When atoms carry an electrical charge they are called ions. Ions are atoms or groups of atoms with a positive or negative charge. Ions are created by atoms losing or gaining, one or more electrons.

Ions - Cations When a neutral atom loses an electron, a positively charged ion results. This is called a cation (cat-eye-on). For example: Na (Sodium) has 11 protons and 11 electrons. It is a neutral sodium atom. It has 1 valence electron. Adding energy to a neutral sodium atom removes the valence electron, leaving a positively charged sodium ion and a free electron.

Ions - Cations Example: Sodium, Na

Ions - Anions When a neutral atom gains an electron, a negatively charged ion results. This is called an anion (an-eye-on). For example: Cl (Chlorine) has 17 protons and 17 electrons. It is a neutral chlorine atom. It has 7 valence electrons. Adding energy to a neutral chlorine atom adds one valence electron, leaving a negatively charged chlorine ion.

Example: Chlorine, Cl

Ions - Conclusion When an atom loses an electron, it becomes a positively charged ion (+), or a cation. When an atom gains an electron, it becomes a negatively charged ion (-), or an anion.

Ionic Compounds Metals form positive ions Non-metals form negative ions So metals and non-metals bond together to create ionic compounds with ionic bonds Metals transfer their electrons to non-metals Both will now have full and stable valence shells

Ionic Compounds In Summary: formed between a metal and non-metal transfer electrons to become stable

Ionic Compounds – an example Sodium chloride, NaCl [Na] 1+ [Cl]1-

Ionic Compounds – an example Calcium chloride, CaCl2

Ionic Compounds – an example Lithium bromide, LiBr