Cation vs. Anion | General Chemistry 1

What is a Cation?

Cations are positively (+) charged ions. They form when a metal loses its electron, and they do not have any protons to balance out the charge so it becomes positive in nature (they lose one or more than one). Some examples include calcium (Ca2+), hydrogen (H+), and potassium (K+). 


What is an Anion?

Anions are negatively (-) charged ions. They form when non-metal gains electrons, which makes it possess a net negative charge. Some examples of anions include chlorine (Cl-), hydroxide (OH-), and Iodide (I–). 


What is the Difference Between Cation and Anion in Simple Terms?

Cation (+) = positively-charged ions, more protons than electrons.

Anion (-) = negatively-charged ions, more electrons than protons.


What are the Similarities Between Cations and Anions?

They are both ions and they both repel similar ions (cations repel cations, anions repel anions). However, they are polar opposites, therefore, cations and anions are attracted to one another. 


How are Cations and Anions Formed?

Cations (positively-charged ions) and anions (negatively-charged ions) are formed when a metal loses electrons, and a nonmetal gains those electrons.  


What is the Difference Between Cations and Anions in Terms of Reactivity?

Cations are more reactive than anions because cations have a greater attraction to electrons. 


What is the Difference Between Cations and Anions in Terms of Stability?

Cations lose electrons to attain stability, whereas Anion gains electrons to attain stability. 


Can Cations and Anions Combine?

Yes, cations and anions can combine. Because they are polar opposites, they attract each other.  They form a binary compound. In this way, for example, sodium ions and chloride anions combine to make table salt.

However, ions that are not opposites repel one another, and, therefore, will not combine.


Cation vs Anion Visual Chart: Differences at a Glance

  Cation Anion
Charge Positive Negative
Attraction Cathode (negative -) Anode (positive +)
How it Forms Metal atoms Non-metal atoms

Why are Ions Called Cation or Anion?

In the 1830s, a physicist and chemist named Michael Faraday first coined the term "ion" which is Greek for "to go." This is because ions move toward the electrode of the opposite charge. Cation is therefore Greek for "down" and the anion is Greek for "up."


What are the Names for Ions with Multiple Charges?

For example, an ion with a −2 charge is known as a dianion and an ion with a +2 charge is known as a dication. A zwitterion is a neutral molecule with positive and negative charges at different locations within that molecule.


Cation Ionic Charges at a Glance

The Roman numeral notation indicates the charge of an ion when an element commonly forms more than one ion. For example, iron(II) has a 2+ charge; iron(III) a 3+ charge.
+1 +2 +3 +4
ammonium NH4+ (Polyatomic)
cesium Cs+
gold(I) Au+ (Monatomic)
hydrogen H+ (Monatomic)
lead(I) Pb+
lithium Li+ (Monatomic)
potassium K+ (Monatomic)
silver Ag+ (Monatomic)
sodium Na+ (Monatomic)
copper(I) Cu+
barium Ba2+ (Monatomic)
beryllium Be2+ (Monatomic)
cadmium Cd2+
calcium Ca2+ (Monatomic)
cobalt(II) Co2+
copper(II) Cu2+ (Monatomic)
iron(II) Fe2+ (Monatomic)
lead(II) Pb2+ (Monatomic)
magnesium Mg2+ (Monatomic)
manganese(II) Mn2+ (Monatomic)
mercury(I) Hg22+ (Polyatomic)
mercury(II) Hg2+ (Monatomic)
nickel(II) Ni2+
strontium Sr2+ (Monatomic)
tin(II) Sn2+ (Monatomic)
zinc Zn2+ (Monatomic)
aluminum Al3+  (Monatomic)
chromium(III) Cr3+ (Monatomic)
cobalt(III) Co3+
gold(III) Au3+ (Monatomic)
hydronium H3O+ (Polyatomic)
iron(III) Fe3+ (Monatomic)
manganese(III) Mn3+ (Monatomic)
tin(IV) Sn4+ (Monatomic)
nickel(IV) Ni4+
lead(IV) Pb4+ (Monatomic)


Anion Ionic Charges at a Glance

There are no common anions with a 4- charge.
1- 2- 3-
acetate C2H3O2-
amide NH2-
bromate BrO3-
bromide Br- (Monatomic)
chlorate ClO3- (Oxoanion)
chlorite ClO2-
chloride Cl- (Monatomic)
cyanide CN-
cyanate OCN-
fluoride F- (Monatomic)
hydride H- (Monatomic)
hydrogen carbonate (bicarbonate) HCO3- (Oxoanion)
hydrogen sulfate (bisulfate) HSO4 (Oxoanion)
hydrogen sulfate (bisulfide) HS-
hydrogen sulfate (bisulfite) HSO3- (Oxoanion)
hydroxide OH- (Oxoanion)
hypochlorite ClO- (Oxoanion)
iodate IO3-
iodide I- (Monatomic)
nitrate NO3- (Oxoanion)
nitrite NO2- (Oxoanion)
perchlorate ClO4- (Oxoanion)
permanganate MnO4- (Oxoanion)
thiocyanate SCN-
carbonate CO32- (Oxoanion)
chromate CrO42- (Oxoanion)
dichromate Cr2O72- (Oxoanion)
oxide O2- (Monatomic)
oxalate C2O42-
silicate SiO32- (Oxoanion)
sulfate SO42- (Oxoanion)
sulfide S2- (Monatomic)
sulfite SO32- (Oxoanion)
tartrate C4H4O62-
tetraborate B4O72-
thiosulfate S2O32- (Oxoanion)
arsenate AsO43-
arsenite AsO33-
citrate C6H5O73-
ferricyanide Fe(CN)63-
nitride N3- (Monatomic)
phosphate PO43- (Oxoanion)
phosphite PO33-
phosphide P3- (Monatomic)


When Naming Ionic Compounds Which Comes First: The Cation or The Anion?

Ionic compounds are named and read with the cation first and the anion last. The central atom is the cation. The small particle that is held by the central atom is called the anion.


What Does the Size of Ions Determine?

The size of an ion can affect several things. The size of an ion influences its packing in lattices, as well as the lattice energy, which can affect how it behaves. For example, some biological recognition systems require that only small ions pass through the membrane channels while others will just accumulate on either side without getting into any useful work. 


What Influences the Size of an Ion?

There are three common properties that can influence the size of an ion. They are the number of electrons, the nuclear charge, and the valence orbitals. Electrons have a negative charge, so when an electron is removed from the atom it leaves behind a positive charge.  


Which is Smaller: Cations or Anions?

Cations are smaller than the parent atom because they've lost electrons. Anions, on the other hand, gain new ones to become larger in size and have a positive charge.