4.2 – Ionic and 4.2 – Ionic and Covalent Compound Covalent Compound

NamingNaming

Science 10Science 10

Ionic Ionic CompoundsCompounds::

are made up of positive and negative are made up of positive and negative ions (a metal ion and a non-metal ion).ions (a metal ion and a non-metal ion).– All of the positives and negatives organize All of the positives and negatives organize

nicely.nicely. Negative-positive attractNegative-positive attract Negative-negative and positive-positive repelNegative-negative and positive-positive repel

– Ionic compounds form from the inside-out Ionic compounds form from the inside-out as solid crystalsas solid crystals

– Ionic compounds are like a solid stack of Ionic compounds are like a solid stack of bricks!bricks! A salt shaker contains thousands of small pieces A salt shaker contains thousands of small pieces

of NaClof NaCl

Salt, NaCl

Covalent Covalent MoleculesMolecules::

share electrons.share electrons.– There is generally no order to the There is generally no order to the

formation of covalent moleculesformation of covalent molecules– These molecules clump together as These molecules clump together as

solids, liquids or gasessolids, liquids or gases

Covalent molecules are like a play-pit Covalent molecules are like a play-pit full of plastic ballsfull of plastic balls Each plastic ball = 1 covalent molecule Each plastic ball = 1 covalent molecule

of Hof H22OO Pit full of balls = swimming pool full of Pit full of balls = swimming pool full of

waterwaterWater, HWater, H22OO

Naming Ionic Compounds:Naming Ionic Compounds:

Ionic compounds are composed of Ionic compounds are composed of cationscations and and anionsanions..– The name of an ionic compound = cation + anionThe name of an ionic compound = cation + anion--ideide

– For example, an ionic compound forms between For example, an ionic compound forms between magnesium and oxygenmagnesium and oxygen The cation is the first part of the name, The cation is the first part of the name, magnesiummagnesium The anion forms part of the ending of the name, The anion forms part of the ending of the name, oxoxygenygen -ide-ide is added to the end of the name to form is added to the end of the name to form magnesium magnesium

oxideoxide.. Magnesium oxide is used as a drying agent.

Ionic formulas are based on the ions Ionic formulas are based on the ions of the atoms involvedof the atoms involvedExample: what is the name of CaExample: what is the name of Ca33NN22??

Ca, the cation, is calciumCa, the cation, is calcium N, the anion, is nitrogenN, the anion, is nitrogen Drop the end of the anion and add Drop the end of the anion and add -ide-ide

Calcium nitrideCalcium nitride

What is the name of BaCl? Barium chlorideBarium chloride

Writing formulas for ionic Writing formulas for ionic compoundscompounds

Remember: Remember: thethe positive charges will positive charges will balance out the negative chargesbalance out the negative charges– The ratio of positive to negative charges The ratio of positive to negative charges

gives the proper formulagives the proper formula The ratio is always written in reduced form!The ratio is always written in reduced form!

– For example, what is the formula for For example, what is the formula for magnesium phosphide?magnesium phosphide?

Magnesium is MgMagnesium is Mg2+2+ phosphorous is Pphosphorous is P3–3–

Lowest common multiple of 2 and 3 is 6Lowest common multiple of 2 and 3 is 6 3 Mg3 Mg2+2+ ions and 2 P ions and 2 P3– 3– ions (six +ve charges and 6 –ve) ions (six +ve charges and 6 –ve) MgMg33PP22

You try!You try!

– What is the formula for calcium oxide?What is the formula for calcium oxide? calcium is Cacalcium is Ca2+2+ oxygen is Ooxygen is O2–2–

1 Ca1 Ca2+2+ ion and 1 O ion and 1 O2– 2– ionsions CaCa22OO22

which is reduced and written as CaOwhich is reduced and written as CaO

Ionic Compound Ionic Compound with a Multivalent Metalwith a Multivalent Metal

Some transitional metals are Some transitional metals are multivalentmultivalent, meaning they have , meaning they have more than one ion form (possible more than one ion form (possible charge).charge).– On the periodic table, the most common On the periodic table, the most common

form of the ion is listed on topform of the ion is listed on top– In the name of the compound, Roman In the name of the compound, Roman

numerals are used after the numerals are used after the

cation to indicate which ion was usedcation to indicate which ion was used

Example:Example:

What is the formula manganese (III) What is the formula manganese (III) sulphide?sulphide?

This manganese is MnThis manganese is Mn3+3+ sulphur is Ssulphur is S2–2–

Lowest common multiple of 3 and 2 is 6Lowest common multiple of 3 and 2 is 6 2 Mn2 Mn3+3+ ions and 3 S ions and 3 S2– 2– ionsions MnMn22PP33

You try!You try!

What is the name for TiFWhat is the name for TiF44?? titanium can be Tititanium can be Ti4+ 4+ oror TiTi3+ 3+ fluorine is fluorine is

FF––

From the ratio in the formula you From the ratio in the formula you

can find out it is Tican find out it is Ti4+ 4+

1 Ti1 Ti4+4+ ion and 4 F ion and 4 F– – ionsions Titanium (IV) fluorideTitanium (IV) fluoride

Polyatomic IonsPolyatomic Ions

Polyatomic ions, are made up of several Polyatomic ions, are made up of several atoms joined together (ironically, joined atoms joined together (ironically, joined with covalent bonds)with covalent bonds)– The whole group has a + or – charge, not The whole group has a + or – charge, not

individual atoms.individual atoms. What is the formula of sodium sulphate?What is the formula of sodium sulphate?

Na+ and SO42–

Na2SO4

What is the name of the compound KClO?What is the name of the compound KClO? K+ = potassium ClO– = hypochlorite

Potassium hypochlorite

What is the formula for Calcium nitrate?Ca2+ and NO3

-

Ca(NOCa(NO33))22

* Note the brackets around NO* Note the brackets around NO33 show there are two of show there are two of the ions presentthe ions present

Names and Formulas of Names and Formulas of Covalent CompoundsCovalent Compounds

Covalent compounds are made Covalent compounds are made up of two or more non-metals up of two or more non-metals sharing valence electronssharing valence electrons– Subscripts mean something Subscripts mean something

different in covalent compoundsdifferent in covalent compounds Ionic compounds subscripts show Ionic compounds subscripts show

smallest whole-number ratio smallest whole-number ratio between the ions in the compoundbetween the ions in the compound

Covalent molecules have subscripts Covalent molecules have subscripts that show the actual number of that show the actual number of atoms in the moleculeatoms in the molecule

Naming Simple Covalent Naming Simple Covalent CompoundsCompounds

Prefixes are used before the atom name to indicate the number of atoms in the molecule.

Examples: CO = carbon monoxide, CO2 = carbon dioxide

Write the most metallic atom (furthest left) first, then add -ide to the end of the second atom’s name

Examples:Examples:

What is the name of the molecule What is the name of the molecule SiSi33PP66??

– TriTrisiliconsilicon hexahexaphosphidephosphide

What is the chemical formula for the What is the chemical formula for the molecule trinitrogen tetrachloride?molecule trinitrogen tetrachloride?– NN33ClCl44

How do you know which type it How do you know which type it is?is?

To determine whether a compound is ionic or To determine whether a compound is ionic or covalent:covalent:1.1.Examine the formulaExamine the formula

• Ionic compounds start with a metal or the ammonium ionIonic compounds start with a metal or the ammonium ion• Covalent compounds start with a non-metalCovalent compounds start with a non-metal

2.2.If the compound is covalent…If the compound is covalent…• Use the prefix systemUse the prefix system

3.3.If the compound is ionicIf the compound is ionic• Check the metal to see if it is multivalent (add a roman Check the metal to see if it is multivalent (add a roman

numeral if it is). numeral if it is). • If it ends with a single non-metal, naming will just end in If it ends with a single non-metal, naming will just end in -ide-ide

• If it ends in a polyatomic ion, look up the name/formulaIf it ends in a polyatomic ion, look up the name/formulaTake the Section 4.2 Quiz