Binary Molecular Compounds compounds made of two nonmetals

Binary Molecular Compounds – compounds made of two non-metals connected by covalent bonds. (Modern Chemistry p. 211 -214) Ionic Compounds – compounds made of positive and negative ions connected by ionic bonds. (Modern Chemistry p. 206 -211)

Molecule Naming • A molecules is the combination of two or more atoms. The atoms are held together by strong forces called bonds. Ammonia NH 3 • Molecules can be represented by a (1) molecular formula, or a (2) structural formula. • In a molecular formula, the number of atoms of each element is shown by a subscript written after the symbol of the element.

Nomenclature Review – Binary Molecular Compounds • The first element, the least electronegative one, is written down unchanged. • The second element, the most electronegative one, is given an “-ide” suffix. • If there is more than one of an atom, a prefix is used to identify the number of atoms. (mono used rarely) • In cases where the prefix ends in an a or an o, the vowel at the end of the prefix is dropped if the lead letter of the element is also a vowel.

Latin/Greek Numeric Prefixes Used in Chemistry 1 – mono 2 – di 3 – tri 4 – tetra Example 5 – penta 6 – hexa 7 – hepta 8 – octa S 4 Br 6 9 – nona 10 – deca 11 – undeca 12 – dodeca 13 – trideca tetrasulfur hexabromide

Ions - Cations • Some molecules are made up of ions. • Ions are formed when atoms lose or gain electrons. • Metal atoms typically tend to lose electrons to Na form positively charged Ca ions called cations. Examples • Na+ Ca 2+ atom Na+ cation + e- atom Ca 2+ cation + 2 e-

Monatomic Ions - Anions • Ions are formed when atoms lose or gain electrons. Nonmetals atoms form negative ions called anions by gaining electrons. Examples Cl- O 2 - Cl atom + e- Cl- anion O atom + 2 e- O 2 - anion

Polyatomic Ions • Some of the most important ions in chemistry are polyatomic ions. They contain more than one atom. We can think of polyatomic ions as “charged molecules”. Examples OH- NH 4+

Ionic Compounds • An ionic compound is a combination of a cation and an anion. This type of compound is held together by strong electrical forces between oppositely charged ions called ionic bonds. Na+ + Cl- Na. Cl • Note the symbol for the metal ion always comes first. A compound is a general term meaning a substance containing more than one element.

Naming Ionic Compounds • A compound can either be identified by its formula (Na. Cl) or its name (sodium chloride). • A monatomic cation (the ion that comes first in the name) takes the name of its metal element. Na+ sodium K+ potassium • But some metals can form more than one type of cation, then we need to use a Roman numeral that represents the charge of the cation after the element name. Fe 2+ iron(II) Fe 3+ iron(III) • A monatomic anion is named by adding the suffix -ide to the stem of its nonmetal element name. N 3 - nitrogen nitride O 2 - oxygen oxide F- fluorine fluoride H- hydrogen hydride

Naming Ionic Compounds • Polyatomic oxoanions (anions that contain oxygen) are named differently. 1) When a nonmetal form many oxoanions, the suffix -ate is used for the anion with the larger number of oxygen atoms. NO 3 - nitrate – Potassium nitrate, KNO 3, (saltpetre) is used in gunpowder The suffix -ite is used for the anion with fewer oxygen atoms. NO 2 - nitrite Potassium nitrite, KNO 2, is used as a food additive

2) When a nonmetal forms more than two oxoanions, in addition to the -ate or -ite suffixes, the prefix per- is used for the largest number of oxygen atoms, • or the prefix hypo- is used for the fewest number of oxygen atoms. Lithium perchlorate is used in lithium batteries • • perchlorate chlorite hypochlorite Cl. O 4 Cl. O 3 Cl. O 2 Cl. O-

Practice Naming Ionic Compounds 1) Mg. S magnesium sulfide -semiconductor that emits blue-green light 2) K 2 O potassium oxide - ancient earthenware glazes 3) Al(NO 3)3 aluminum nitrate - oil refining, dyeing, leather tanning 4) Fe. Cl 2 iron(II) chloride - waste water treatment 5) Cu 3 BO 3 copper(I) borate -

Writing Ionic Formulas Na+ + Cl- Na. Cl sodium chloride Note the symbol for the metal ion always comes first. sodium bromide sodium hydroxide sodium sulfide sodium nitride Na+ Br- Na+ Na+ OH 1 - S 2 N 3 - Na. Br Na. OH Na 2 S Na 3 N

More Practice Monoatomic Ions 1) Cs. I 2) Ni. P 3) Cd. F 2 4) Strontium telluride 5) Boron bromide 6) Bismuth(III) carbide

More Practice Polyatomic Ions 7) Au(Cl. O)3 8) Ca. C 2 O 4 9) V 3(PO 3)2 10) Hydrogen cyanide 11) Stannic hydroxide 12) Polonium(IV) chromate