nomenclature ionic compounds. learning goals we are learning to – name ionic compounds –...
TRANSCRIPT
NomenclatureIonic
Compounds
Learning Goals
• We are learning to – Name ionic compounds – Understand the charges of ions in ionic compounds– Use what we know
about ionic charge todetermine chemicalformulas
– Name ionic compounds containing polyatomic ions
Ionic Compounds
Recall: • An ionic compound is formed from one or
more positively charged ions and one or more negatively charged ions
• In ionic bonding, electrons are transferred from one atom to another.
• The oppositely charged ions are attracted to each other by electrostatic forces, which are the basis of the ionic bond.
Ionic Bonding
• Metals lose electrons, become positively charged – sodium, potassium, magnesium, calcium
• Non-metals gain electrons, become negatively charged– chlorine, silicon, oxygen, sulphur
• The result of bonding is a compound that has an overall neutral charge
Drawing Chemical Symbols
• When a sodium atom loses one electron and becomes a positively charged ion it is symbolized as: Na+ to indicate a charge of +1– When more than one electron is exchanged the
number is placed before the charge. – sulfur gains 2 electrons is symbolized as S2-
• What about the following elements?– chlorine gains 1 electron– calcium loses 2 electrons– oxygen gains 2 electrons– aluminum loses 3 electrons
Ionic Formula
• The formula of an ionic compound is derived by combining ions such that a neutral compound is created
• Let’s try some examples:– calcium and chlorine– magnesium and oxygen– lithium and bromine– magnesium and nitrogen
Naming Ionic Compounds
1. Name the metal ion first – same as element name• In KBr the name of the K+ ion is potassium.
2. Name the non-metal ion second. When non-metal becomes a negative ion, the ending of its name changes to “ide”• A bromine atom gains an electron to become a bromide ion
3. Combine the names• The name of KBr is potassium bromide
Naming Ionic Compounds
• Let’s try some examples:– calcium and chlorine– magnesium and oxygen– lithium and bromine– magnesium and nitrogen
Naming Ionic Compounds
• Some metals are able to form more than one kind of ion– EXAMPLES: copper, lead, iron, nickel
• Roman numerals are used to indicate ionic charge– EXAMPLE: There are two types of copper ions: Cu+
and Cu2+
• Copper(I) chloride: Cu+ forms the compound (CuCl)• Copper(II) chloride: Cu2+ forms the compound (CuCl2)
Naming Ionic Compounds
• You can determine the Roman Numeral to use in the name of a multivalent ion from the subscripts in the compounds formula.– EXAMPLE: CrCl3
– Chlorine holds a charge of -1 and there are 3 of them in the chemical formula, therefore to make the molecule neutral the chromium must have a charge of +3.
– Name is chromium(III) chloride
Naming Ionic Compounds
• Let’s try some examples:– FeCl2
– FeCl3
– CuN2
– Ni2O3
Exit Ticket
Please hand in before you go
Homework
Complete the handout