Common Polyatomic Ions, Acids, and Molecular Geometries

Vocabulary practice flashcards covering common polyatomic ions, binary and oxyacids, and VSEPR electron and molecular geometries.

Mercury(I) ion

A polyatomic cation with the formula $Hg_2^{2+}$.

Ammonium ion

A polyatomic cation with the formula $NH_4^+$.

Nitrite ion

A polyatomic anion with the formula $NO_2^-$.

Nitrate ion

A polyatomic anion with the formula $NO_3^-$.

Sulfite ion

A polyatomic anion with the formula $SO_3^{2-}$.

Sulfate ion

A polyatomic anion with the formula $SO_4^{2-}$.

Hydrogen sulfate ion

A polyatomic anion with the formula $HSO_4^-$ (bisulfate is a widely used common name).

Hydroxide ion

A polyatomic anion with the formula $OH^-$.

Cyanide ion

A polyatomic anion with the formula $CN^-$.

Phosphate ion

A polyatomic anion with the formula $PO_4^{3-}$.

Hydrogen phosphate ion

A polyatomic anion with the formula $HPO_4^{2-}$.

Dihydrogen phosphate ion

A polyatomic anion with the formula $H_2PO_4^-$.

Thiocyanate ion

A polyatomic anion with the formula $NCS^-$ or $SCN^-$.

Carbonate ion

A polyatomic anion with the formula $CO_3^{2-}$.

Hydrogen carbonate ion

A polyatomic anion with the formula $HCO_3^-$ (bicarbonate is a widely used common name).

Hypochlorite ion

A polyatomic anion with the formula $ClO^-$ or $OCl^-$.

Chlorite ion

A polyatomic anion with the formula $ClO_2^-$.

Chlorate ion

A polyatomic anion with the formula $ClO_3^-$.

Perchlorate ion

A polyatomic anion with the formula $ClO_4^-$.

Acetate ion

A polyatomic anion with the formula $C_2H_3O_2^-$.

Permanganate ion

A polyatomic anion with the formula $MnO_4^-$.

Dichromate ion

A polyatomic anion with the formula $Cr_2O_7^{2-}$.

Chromate ion

A polyatomic anion with the formula $CrO_4^{2-}$.

Peroxide ion

A polyatomic anion with the formula $O_2^{2-}$.

Oxalate ion

A polyatomic anion with the formula $C_2O_4^{2-}$.

Thiosulfate ion

A polyatomic anion with the formula $S_2O_3^{2-}$.

Hydrofluoric acid

An aqueous acid solution with the chemical formula $HF$.

Hydrochloric acid

An aqueous acid solution with the chemical formula $HCl$.

Hydrobromic acid

An aqueous acid solution with the chemical formula $HBr$.

Hydroiodic acid

An aqueous acid solution with the chemical formula $HI$.

Hydrocyanic acid

An aqueous acid solution with the chemical formula $HCN$.

Hydrosulfuric acid

An aqueous acid solution with the chemical formula $H_2S$.

Nitric acid

An acid with the chemical formula $HNO_3$.

Nitrous acid

An acid with the chemical formula $HNO_2$.

Sulfuric acid

An acid with the chemical formula $H_2SO_4$.

Sulfurous acid

An acid with the chemical formula $H_2SO_3$.

Phosphoric acid

An acid with the chemical formula $H_3PO_4$.

Acetic acid

An acid with the chemical formula $HC_2H_3O_2$.

Linear geometry (2 electron groups)

The molecular geometry formed by $2$ electron groups ($2$ bonding groups and $0$ lone pairs), featuring an approximate bond angle of $180^\circ$ (e.g., $CS_2$).

Trigonal planar geometry (3 electron groups)

The molecular geometry formed by $3$ electron groups ($3$ bonding groups and $0$ lone pairs), featuring an approximate bond angle of $120^\circ$ (e.g., $BCl_3$).

Bent geometry (3 electron groups)

The molecular geometry formed by $3$ electron groups ($2$ bonding groups and $1$ lone pair) with trigonal planar electron geometry and an approximate bond angle of $<120^\circ$ (e.g., $SO_2$).

Tetrahedral geometry (4 electron groups)

The molecular geometry formed by $4$ electron groups ($4$ bonding groups and $0$ lone pairs), featuring an approximate bond angle of $109.5^\circ$ (e.g., $CH_4$).

Trigonal pyramidal geometry

The molecular geometry formed by $4$ electron groups ($3$ bonding groups and $1$ lone pair) with tetrahedral electron geometry and an approximate bond angle of $<109.5^\circ$ (e.g., $PH_3$).

Bent geometry (4 electron groups)

The molecular geometry formed by $4$ electron groups ($2$ bonding groups and $2$ lone pairs) with tetrahedral electron geometry and an approximate bond angle of $<<109.5^\circ$ (e.g., $H_2S$).

Trigonal bipyramidal geometry (5 electron groups)

The molecular geometry formed by $5$ electron groups ($5$ bonding groups and $0$ lone pairs), featuring approximate bond angles of $120^\circ$ (equatorial) and $90^\circ$ (axial) (e.g., $PCl_5$).

Seesaw geometry

The molecular geometry formed by $5$ electron groups ($4$ bonding groups and $1$ lone pair) with trigonal bipyramidal electron geometry and approximate bond angles of $<120^\circ$ (equatorial) and $<90^\circ$ (axial) (e.g., $SF_4$).

T-shaped geometry

The molecular geometry formed by $5$ electron groups ($3$ bonding groups and $2$ lone pairs) with trigonal bipyramidal electron geometry and an approximate bond angle of $<90^\circ$ (e.g., $ClF_3$).

Linear geometry (5 electron groups)

The molecular geometry formed by $5$ electron groups ($2$ bonding groups and $3$ lone pairs) with trigonal bipyramidal electron geometry and an approximate bond angle of $180^\circ$ (e.g., $XeF_2$).

Octahedral geometry (6 electron groups)

The molecular geometry formed by $6$ electron groups ($6$ bonding groups and $0$ lone pairs), featuring an approximate bond angle of $90^\circ$ (e.g., $SF_6$).

Square pyramidal geometry

The molecular geometry formed by $6$ electron groups ($5$ bonding groups and $1$ lone pair) with octahedral electron geometry and an approximate bond angle of $<90^\circ$ (e.g., $BrF_5$).

Square planar geometry

The molecular geometry formed by $6$ electron groups ($4$ bonding groups and $2$ lone pairs) with octahedral electron geometry and an approximate bond angle of $90^\circ$ (e.g., $XeF_4$).