Chemistry Foundations: Elements, Ions, Solubility, and Significant Figures

Vocabulary flashcards covering element classifications, ion naming and formulas, solubility rules, and significant figure rules.

BrINClHOF Twins

The seven diatomic elements that naturally exist as two-atom molecules: $Br_2$, $I_2$, $N_2$, $Cl_2$, $H_2$, $O_2$, and $F_2$.

Liquid Elements at Standard Conditions

The two elements that exist as liquids at standard conditions: mercury ($Hg$) and bromine ($Br$).

Alkali Metal Cations

Group 1 elements that lose one electron to form cations with a $1+$ charge and retain their elemental name.

Alkaline Earth Metal Cations

Group 2 elements that lose two electrons to form cations with a $2+$ charge.

Anion Naming (-ide ending)

Monoatomic anions formed when nonmetals gain electrons, named by taking the root of the element name and adding the suffix '-ide' (e.g., chloride, oxide).

Roman Numeral Notation in Naming

A system where a Roman numeral in parentheses immediately following the metal name denotes the positive charge of a metal that forms multiple cations (e.g., Iron(III) for $Fe^{3+}$).

-ate vs. -ite Suffixes

A structural relationship in polyatomic anions where the '-ate' ion contains one more oxygen atom than the '-ite' ion while maintaining the same ionic charge (e.g., sulfate $SO_4^{2-}$ vs. sulfite $SO_3^{2-}$).

Hypo- Prefix

A prefix meaning 'under' or 'too little' used for an oxyanion that has one less oxygen atom than the corresponding '-ite' ion (e.g., hypochlorite $ClO^-$ has one less oxygen than chlorite $ClO_2^-$).

Per- Prefix

A prefix derived from 'hyper' (meaning 'above' or 'too much') used for an oxyanion that has one more oxygen atom than the corresponding '-ate' ion (e.g., perchlorate $ClO_4^-$ has one more oxygen than chlorate $ClO_3^-$).

Hydrogen Addition to Polyatomic Anions

Adding a hydrogen ion ($H^+$) to a polyatomic anion adds an $H$ atom to the front of the formula and makes the net charge less negative by one (e.g., phosphate $PO_4^{3-}$ becomes hydrogen phosphate $HPO_4^{2-}$).

Always Soluble Polyatomic Anions

Anions whose compounds are always soluble: nitrate ($NO_3^-$), chlorate ($ClO_3^-$), perchlorate ($ClO_4^-$), and acetate ($C_2H_3O_2^-$).

Halide Solubility Rule

Compounds containing chloride ($Cl^-$), bromide ($Br^-$), and iodide ($I^-$) are soluble EXCEPT when combined with $Ag^+$, $Pb^{2+}$, or $Hg_2^{2+}$.

Sulfate Solubility Rule

Compounds containing sulfate ($SO_4^{2-}$) are soluble EXCEPT when combined with $Ba^{2+}$, $Sr^{2+}$, $Ca^{2+}$, $Pb^{2+}$, or $Hg_2^{2+}$.

Hydroxide and Sulfide Solubility Rule

Compounds containing hydroxide ($OH^-$) and sulfide ($S^{2-}$) are insoluble EXCEPT when combined with $NH_4^+$, alkali metals, $Ba^{2+}$, $Sr^{2+}$, or $Ca^{2+}$.

Sulfites, Carbonates, Chromates, and Phosphates Solubility Rule

All sulfites ($SO_3^{2-}$), carbonates ($CO_3^{2-}$), chromates ($CrO_4^{2-}$), and phosphates ($PO_4^{3-}$) are insoluble EXCEPT when combined with $NH_4^+$ or alkali metals.

Pacific Rule for Significant Figures

A counting rule used when a decimal point is PRESENT: start from the Pacific (left) side at the first non-zero digit ($1$–$9$) and count every digit to the right.

Atlantic Rule for Significant Figures

A counting rule used when a decimal point is ABSENT: start from the Atlantic (right) side at the first non-zero digit ($1$–$9$) and count every digit to the left.

Addition and Subtraction Sig Fig Rule

A calculation rule requiring the final result to have the same number of decimal places as the number in the problem with the fewest decimal places.

Multiplication and Division Sig Fig Rule

A calculation rule requiring the final result to have the same number of significant figures as the number in the problem with the fewest total significant figures.

Measurement Precision Rule

A measurement rule stating that reported measurements must include all certain digits from device divisions plus exactly one estimated digit.

Hydronium Ion

A polyatomic cation with the formula $H_3O^+$.

Ammonium Ion

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

Mercury(I) Ion

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

Permanganate Ion

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

Dichromate Ion

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

Oxalate Ion

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

Thiosulfate Ion

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

Thiocyanate Ion

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

Peroxide Ion

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

Borate Ion

A polyatomic anion with the formula $BO_3^{3-}$.