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Naming Ions

Naming Ions. What is a Monatomic Ion?. A monotomic ion consists of a single atom with a positive or negative charge resulting from the loss or gain of valence electrons

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Naming Ions

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  1. Naming Ions

  2. What is a Monatomic Ion? • A monotomic ion consists of a single atom with a positive or negative charge resulting from the loss or gain of valence electrons • A cation is an ion with a positive charge. Metals in groups 1A, 2A, and 3A form a cation with the same charge as their group number • The names of cations in these groups is the name of the element followed by ion or cation. • Example: Na+ is sodium ion or sodium cation • Ca2+ is calcium ion or calcium cation

  3. Naming Anions • An anion is an atom that has gained electrons and thus has a negative charge • The charge of a nonmetal anion in group A is determined by subtracting 8 from the group number. • Elements in group 7A have a charge of -1 (7-8=-1) • The name of an anion is not the same as the element’s name • Anion names have the root of the element name with –ide added to it. • Example: A chlorine ion is called chloride, and oxygen ion in called oxide

  4. Practice • Fluorine Ion • Bromine Ion • Selenium Ion • Nitrogen Ion • Fluoride • Bromide • Selenide • Nitride

  5. Ions of Transition Metals • Transition metals do not form consitant charges when ioninzing like elements in the A group • They can form multiple ions • Iron can form Fe2+ and Fe3+ • These cations are named differently than others. • When naming an ion of a transition metal, write the name of the element folowed by it’s charge written in roman numerals following it. • Example: Fe2+ is written as iron (II) and Fe3+ is written as iron (III)

  6. Exceptions • Some transition metals have only one ionic charge. • The names of these elements do not have a roman numeral • These excepetions include silver (Ag+), cadmium (Cd2+), and zinc (Zn2+)

  7. Practice • Pb2+ • Pb4+ • Cr2+ • Cr3+ • lead (II) • lead (IV) • chromium (II) • chromium (III)

  8. Polyatomic Ions • A polyatomic ion is an ion composed of more than one atom. • The names of most polyatomic ions in in –ite or –ate. • All polyatomics ending in –ite or –ate contain oxygen

  9. Adding Hydrogen • When the formula for a polyatomic ion contains hydrogen, it is a combination of an H+ ion and another polyatomic ion • H+ + CO32- (carbonate) -> HCO3- hydrogen carbonate • H+ + PO43- (phosphate) -> HPO42- hydrogen phosphate

  10. Naming Compounds with Polyatomic Ions • Naming a compound with a polyatomic ion works the same as with other ionic compounds • Name the cation first then the anion • Use the name of the polyatomic ion when naming.

  11. Example

  12. Naming and Writing Ionic Compounds

  13. What is a Binary Ionic Compound • A binary ionic compound is composed of two elements joined by an ionic bond. • To name a binary ionic compound place the name of the cation first, followed by the name of the anion. • The compound must remain neutral • Example: NaBr would be sodium bromide • Example: CuO would be copper (II) oxide • This is known because the charge of oxygen is a 2-, so copper must have a charge of 2+ for the compound to be neutral

  14. Cu2O • SnF2 • SnS2 • copper (I) oxide • tin (II) fluoride • tin (IV) fluoride

  15. Writing formulas for binary ionic compounds • If you know the name of a binary ionic compound, you can write it’s formula • The net charge of the compound must be zero • First figure out the charge of the atoms in the name of the compound • Then use the charge of one compound as the subscript for the other compound • Then reduce to the lowest whole number ratio

  16. Example • Write the formula for calcium sulfide • From the periodic table, the charge of calcium is 2+ • From the periodic table, the charge of sulfur is 6 -8 = -2 or S2- • Ca2+ and S2- crossing the charges gives Ca2S2 • Reducing to the lowest whole number ratio gives CaS

  17. Example • Write the formula for iron (III) oxide • From the name of the ionic compound, the charge of iron is Fe3+ • From the periodic table, the charge of oxygen is 6 -8 = -2 or O2- • Fe3+ and O2- crossing the charges gives Fe2O3

  18. Practice • copper (II) sulfide • potassium nitride • CuS • K3N

  19. Compounds with Polyatomic Ions • Compounds with polyatomic ions behave the same as those without • The method for writing their formula is the same as ordinary ionic compounds, except you look up the charge from a table of polyatomic ions instead of the periodic table

  20. Example • Write the formula for calcium nitrate • From the periodic table, the charge of calcium is 2+ • From the polyatomic table, the charge of nitrate is 1- • Ca2+ and NO3- crossing the charges gives Ca(NO3)2 • For a polyatomic ion, the subscript is written on the outside of the parenthesis

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