nitrate
Ammonium, NH4+
The polyatomic ion that forms a neutral compound when combined with a Group IA monatomic ion in a 1:1 ratio is the nitrate ion (NO₃⁻). When the nitrate ion pairs with a Group IA cation, such as sodium (Na⁺), they create a neutral compound like sodium nitrate (NaNO₃). This 1:1 ratio ensures that the positive charge of the monatomic ion balances the negative charge of the polyatomic ion.
The ionic compound containing the polyatomic ion NaNO₃ is sodium nitrate. It consists of sodium ions (Na⁺) and nitrate ions (NO₃⁻). In this compound, each sodium ion pairs with one nitrate ion, resulting in a neutral compound that is commonly used as a fertilizer and in food preservation.
To find the charge on a chemical formula, first identify the oxidation states of the individual elements based on their typical charges in compounds. Sum these oxidation states to determine the overall charge of the compound. For ionic compounds, the total positive charge from cations should balance the total negative charge from anions, resulting in a neutral compound. If the compound is polyatomic, refer to the known charge of the polyatomic ion.
Titanium dioxide (TiO2) is a neutral compound, meaning it does not have a positive or negative charge overall. In its pure form, the individual titanium and oxygen atoms within TiO2 do have specific charges, but when combined in the compound, they balance out to give a neutral charge.
Ammonium, NH4+
The sulfate ion (SO4^2-) forms a neutral compound when combined with a group 1A monatomic ion such as potassium (K+) in a 1:2 ratio. This results in the formation of K2SO4, which is a neutral compound.
The polyatomic ion that forms a neutral compound when combined with a Group IA monatomic ion in a 1:1 ratio is the nitrate ion (NO₃⁻). When the nitrate ion pairs with a Group IA cation, such as sodium (Na⁺), they create a neutral compound like sodium nitrate (NaNO₃). This 1:1 ratio ensures that the positive charge of the monatomic ion balances the negative charge of the polyatomic ion.
Since Group 1A monatomic ions have a charge of 1+, only a polyatomic ion with a charge of 1- can combine to form a compound in which the monatomic ions and polyatomic ions are present in a 1 to 1 ratio. The following polyatomic ions with a charge of 1- can form a neutral compound when combined with a group of 1A monatomic ion in a 1 to 1 ratio.acetate - C2H3O2-bicarbonate (or hydrogen carbonate) - HCO3-bisulfate (or hydrogen sulfate) - HSO4-chlorate - ClO3-chlorite - ClO2-cyanate - OCN-cyanide - CN-dihydrogen phosphate - H2PO4-hydroxide - OH-nitrate - NO3-nitrite - NO2-perchlorate - ClO4-permanganate - MnO4-thiocyanate - SCN- Source: http://chemistry.about.com/od/chartstables/tp/common-polyatomic-ions.htm
Sodium sulfate is an ionic compound, composed of monatomic and monovalent sodium cations and polyatomic and divalent sulfate anions. The anions are internally covalently bonded, but are not compounds because they are not electrically neutral.
Polyatomic ions are not compounds because they are not electrically neutral, and they are not elements because they can be broken down into other chemical constituents -- the actual elements.
By definition, a compound is always neutral. If the polyatomic chemical entity has a charge, it is no longer a compound, but is now a polyatomic ion. Ionic compounds and molecular compounds are also neutral in charge. The word "ionic" is just referring to the type of chemical bond in the molecule.
The ionic compound containing the polyatomic ion NaNO₃ is sodium nitrate. It consists of sodium ions (Na⁺) and nitrate ions (NO₃⁻). In this compound, each sodium ion pairs with one nitrate ion, resulting in a neutral compound that is commonly used as a fertilizer and in food preservation.
The compound formed between a sodium ion (Na+) and a phosphate polyatomic ion (PO4 3-) is sodium phosphate (Na3PO4). This ionic compound is formed through the combination of three sodium ions and one phosphate ion, resulting in a neutral compound.
If aluminum and calcium were to combine, the resulting compound would likely be a binary ionic compound with the formula Al2Ca3. This compound would consist of aluminum ions (Al3+) and calcium ions (Ca2+) combined in a 2:3 ratio to achieve a neutral charge.
For a neutral molecule it is zero, for polyatomic ions the sum is the same as the ionic charge.
In a pure element, the oxidation number is zero. In a monatomic ion, the oxidation number is equal to the charge of the ion. Oxygen is typically assigned an oxidation number of -2, unless in a peroxide where it is -1. Hydrogen is typically assigned an oxidation number of +1 when bonded to nonmetals and -1 when bonded to metals. The sum of the oxidation numbers in a neutral compound is zero, and in a polyatomic ion it is equal to the charge of the ion.