Question

Name the cation present in Calcium carbonate a) Ca+ b) Ca2+ c) CO3 2- d) Co3

Answer 1

Answer:

Name the cation present in Calcium carbonate a) Ca+ b) Ca2+ c) CO3 2- d) Co3Chapter!3:!Ions,!Ionic!Compounds,!and!Nomenclature.

An!ion is!a!small!particle!having!an!electrical!charge.!!Ions!are!either!single,

charged!atoms!(simple)ions),!or!small charged “molecules”!(polyatomic ions).!!

Examples!of!simple!ions!are Na+,!Ca+2,!ClE

,!and!SE2.!!Examples!of!polyatomic ions!are!

NH4

+ ,!CO3

!2 , and!OH! .!!Positively!charged!ions are!called!cations (pronounced!catE

eyeEons)!while!negatively!charged!ions are!called!anions (pronounced!anEeyeEons).!!

In!many!cases,!the!elements!position!on!the!periodic!table!will!help!you!determine!

the!kind!of!ion!formed!(anion!or!cation)!and!the!size!of!the!ionic!charge.

Look!at!the!periodic!table (PeriodicTable.pdf!or!the!equivalent).!!Starting!

with!boron!(atomic!number!5)!and!continuing!downwards!and!to!the!right!to!

astatine!(atomic!number!85),!there!is!a!bold!“staircase” shaped!red!line.!!Elements!to!

the!left!of!this!line!are!metals,!and!commonly!form!cations.!!Elements!to!the!right!of!

this!line!are!nonEmetals,!and!commonly!form!anions.!!Some!of!the!elements!adjacent!

to!the!line!are!called!“metalloids”,!but!this!distinction!doesn’t!help!us,!so!don’t!

concern!yourself!with!it.

Starting!on!the!left!of!the!periodic!table,!we!see!groups labeled!“I!A”,!“II!A”,!III!

B”,!and!so!on. On!some newer!versions!of!the!periodic!table,!the!groups are!

numbered!1!E 18.!!I!will!use!the!older!version,!and!show!the!new!group!numbers!in!

parenthesis.

The!elements!in!any!particular!group!tend!to!form!ions!with!characteristic!

charges.!!Please!note,!some!elements!are!capable!of!having!a!range of!electrical!

charges,!and!therefore!form!different!ions.

Group!I!A!(1) elements!form!cations!with +1!charge.

Group!II!A!(2) elements!form!cations!with +2!charge.

Groups!III!B!through!II!B!(3 – 12) are!transition!metals.!!These!elements!form

cations!having!varying amounts of!charge.!!Charges of!+2!or!+3!are!common,!but

charges from!+1!to!+6 can!be!found.!!There!is!no!simple!way!of!accurately!predicting!

the!charges for!these!elements.

Group!III!A!(13)!metals!form!cations!with!+3!charge.!!Please!note!that!the!first!

element!in!this!group,!boron!(B)!is!a!nonEmetal!and!typically!doesn’t!form!a!cation.

Group!IV!A (14)!metals!form!cations!with +4!charge,!although!tin!(Sn) and!lead!(Pb)!

can!form!cations!having +2!charge.!!Generally,!metals!in!this!group!are!treated!

similarly!to!the!“B”!elements.!!The!nonEmetals!carbon!(C)!and!silicon!(Si)!generally!Group!V!A (15)!nonEmetals!(nitrogen!(N),!phosphorous!(P))!form!anions!with a!–3!

charge.!!Arsenic!(As)!anion!has!E3!charge,!but!also forms!cations!with!+3!or!+5!

charge.!!Bismuth!(Bi)!behaves!similarly!to!arsenic.

Group!VI (16)!nonEmetals form!anions!having!–2!charge.!!Polonium!(atomic!number!

84)!forms!only!cations.

Group!VII!A (17)!elements!form!anions!having!–1!charge.

Group!VIII!A (18)!elements!are!normally!uncharged.

Figure!3.1!below!summarizes!the!typical!charges!on!anions!and!cations.

Figure!3.1.!!Pattern!of!Ionic!Charges.

Nomenclature,of,simple,ions

There are!only!two!rules!for!naming!simple!ions.

Rule!1:!!Cations.!!Naming!the!element!and!adding!the!word!“ion”!forms!the!

cation!name.!!So,!Na+ is!“sodium!ion”.!!Ca+2 is “calcium!ion”.!!Al+3 is!“aluminum!ion”.!!

For!transition!metal cations from!groups!III!B!– II!B (3!E 12),!the!cation!name is!the!

name!of!the!element,!plus!the!size of!the!ionic!charge.!!For!example,!Fe+3 is!“iron!

three!ion”.!!Pb+2 is!“lead!two!ion”.!!When!writing!these!names,!we!commonly!use!

Roman!numerals!in!parenthesis!to!indicate!charge!size.!!“Iron!three!ion”!is!written!as!Fe(III),!while!“lead!two!ion”!is!written!as!Pb(II).!!NOTE:!!while!either!Fe+3 or!

Fe(III)!can!be!used!to!identify!the!ion,!Fe(III)+3 is!just!wrong.

Cations!formed!from!the!metallic!elements!in!Groups!III!A!– VII!A;!gallium!

(Ga),!germanium!(Ge),!indium!(In),!tin!(Sn),!antimony!(Sb),!thallium!(Tl),!lead!(Pb),!

and!bismuth!(Bi),!are!named!like!the!transition!metals.!!The!nonmetals!arsenic!(As),!

tellurium!(Te)!and!selenium!(Se)!are!also!named!like!the!transition!metals,!and!can!

form!either!cations!or!anions.

Rule!2:!anions.!!The!anion!name is!formed!from!the!name!of!the!element,!but!

“ide”!replaces the!normal!ending!in!the!elements!name.!!So!ClE is!the!ion!formed!from!

chlorine and!its!name!is!chloride,ion.!!!NE3 is!the!ion!formed!from!nitrogen and!its!

name!is!nitride,ion.!!SE2 is!the!ion!formed!from!sulfur and!its!name!is!sulfide,ion.!!

Sometimes,!the!names!of!simple!anions!are!given!without!“ion”,!!)