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In the ionic compound AmBn, which element is the cation? |
In the ionic compound AmBn, A is the cation because the cation is always written first in the formula for an ionic compound. |
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Which element can replace X in the formula Mg3X2? |
Phosphorus can replace X in the formula Mg3X2 because three magnesium ions have a total charge of 6+ and a 6- charge is needed to balance the charge. If there are two "X" ions, they would each need to have a charge of 3-, which phosphorus has when it forms an ion. |
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An ionic compound has the formula X2O. Identify the element, X. |
Potassium can be the cation in the ionic compound X2O. To balance the 2- charge of the oxygen, two of the unknown cation should have a 2+ charge. This means that each cation should have a 1+ charge. Of the options given, potassium and hydrogen have 1+ charges. However, H2O is a covalent compound. |
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Which pair of elements will form an ionic compound with a 1:2 ratio between the cation and anion? |
Magnesium and bromine form the ionic compound, MgBr2, which has a ratio of 1:2 between the cation and anion. Magnesium forms a 2+ charge and needs two bromide ions (1- charge) to balance the 2+ charge. |
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What is the formula for the compound formed from calcium and oxygen? |
The compound formed from calcium and oxygen has the formula CaO. Calcium has a 2+ charge and oxygen has a 2- charge. For ionic compounds, the subscripts are reduced to the lowest ratio, which is 1:1 in this instance, because ionic compounds exist as a continuous network and not as discrete molecules with a fixed number of ions. |
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What ions compose the compound magnesium phosphide? |
Mg2+ and P3- compose the compound magnesium phosphide. Magnesium is a metal and becomes a cation with a 2+ charge because it donates two electrons when forming an ionic compound. Phosphorus is a nonmetal that forms an anion with a 3- charge. Having three magnesium ions and two phosphorus ions creates a charge balance between the two ions in the compound. |
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What is the correct formula for the compound made from sodium and oxygen? |
The correct formula for the compound formed from sodium and oxygen is Na2O. The sodium cation has 1+ charge and the oxide anion has a 2- charge. Therefore, two sodium cations are needed to balance the 2- charge of the oxygen anion. |
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An ionic compound has the general form, XCly. Which option for X and y correctly completes the formula? |
Beryllium will replace X with a subscript of 2 for chloride to correctly complete the formula XCly as BeCl2. Aluminum chloride has the formula AlCl3, boron forms the compound BCl3, and cesium chloride has the formula CsCl. The subscripts tell the number of each ion needed to balance the charges between the cations and anions. |
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Which one of the listed elements will form an ion with a 2+ charge? |
Calcium will form an ion with a 2+ charge. Calcium and cesium are both metals and will form cations (ions with a positive charge). However, only calcium will form a cation with a 2+ charge. Cesium, found in the first group with one valence electron, will form a 1+ charge. Both chlorine and oxygen are nonmetals and will form anions (ions with a negative charge) because they are gaining electrons in an ionic compound. |
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What is the formula for the ionic compound formed from barium and phosphorus? |
Barium and phosphorus form an ionic compound with the formula Ba3P2. Three barium ions (2+ charge) and two phosphorus ions (3- charge) are needed to balance the charges between the cation and anion. |
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Which one of the following correctly pairs the element and the charge it forms in an ionic compound? |
Lithium forms an ion with a 1+ charge because it donates one electron to the element forming the anion in the compound. Magnesium is a metal and forms a 2+ charge. Oxygen accepts two electrons in an ionic compound and forms a 2- charge, while chlorine accepts one electron to form an ion with a 1- charge. |
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Which group contains only elements that will form cations in ionic compounds? |
Sodium, magnesium, and aluminum will all form cations in ionic compounds. Metals form cations and nonmetals form anions in ionic compounds. |
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Which one of the ions will form an ion with a 1- charge in an ionic compound? |
Fluorine will form a 1- charge in an ionic compound as it gains an electron to become an anion. |
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Which ionic compound is possible? |
Potassium oxide has the formula K2O because potassium has a 1+ charge and two potassium ions are needed to balance the 2- charge of the oxide ion. |
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What is the name for the compound with the formula Ba3N2? |
Barium nitride is the correct name for the compound with the formula Ba3N2. Ba is the chemical symbol for barium and N is the symbol for nitrogen. The name of the cation is always given first and the name is unchanged from the name of the element. The name of the anion is written second and for monatomic anions, the ending is changed to "ide". Prefixes are not needed because they are only used in molecular compound names. |
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What is the formula for the compound made from beryllium and bromine? |
The formula for the compound made from beryllium and bromine is BeBr2. Beryllium has a 2+ charge and bromine has a 1- charge, so two bromine ions are needed to balance the charge of one beryllium ion. |
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Which one of the following pairs will form an ionic compound with a 1:1 ratio between the cation and anion? |
Calcium and sulfur form an ionic compound with a 1:1 ration between the cation and anion because calcium forms a 2+ charge and sulfur forms a 2- charge in an ionic compound. |
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Which group contains only elements that can form anions in ionic compounds? |
Nitrogen, oxygen, and fluorine will all form anions in ionic compounds. Metals form cations and nonmetals form anions in ionic compounds. |
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In the ionic compound XY3, if X has a charge of __________ then Y has a charge of __________. |
In the ionic compound XY3, if X has a charge of 3+ then Y has a charge of 1-. Since there are three Y ions for every one X, the charge on X must be three times the magnitude of the charge on Y. In an ionic compound, the cation is always written first so X must be positively charged. |
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What is the name for the compound with the formula MgCl2? |
The name for MgCl2 is magnesium chloride. When naming ionic compounds, the name of the cation is left unchanged and the ending of a monatomic anion is changed to "ide" which means magnesium chlorine is incorrect. |
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What is the name for the compound with the formula RbF? |
Rubidium fluoride is the name for the ionic compound with RbF. For ionic compounds, the cation name is the same name as the element and is written first. The anion is named second and is the name of the element with the ending changed to "ide". |
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A compound has the formula Al2X3. Which one of the following could be X? |
Sulfur could be X. Given the formula, Al2X3, the charge on X must be 2- in order to balance the charge of the two aluminum ions (3+ charge on each). Of the given elements, only sulfur will form an anion with 2- charge. |
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Which pair of ions will form an ionic compound with a 1:1 ratio? |
Calcium and sulfur will form an ionic compound with a 1:1 ratio since they have 2+ and 2- charges, respectively. To form an ionic compound, the cation charge must balance the anion charge. |
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What is the name for the ionic compound formed from Sr and P? |
Strontium phosphide is the name for the compound formed from Sr and P. For ionic compounds, the cation retains the name of the element and the monatomic ion has its ending changed to "ide". |
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Which one of the following is an ionic compound? |
AlBr3 is an ionic compound because it is composed of a metal and a nonmetal. |
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What ionic compound is formed from cesium and nitrogen? |
Cs3N is the ionic compound formed from cesium and nitrogen. Cesium forms an ion with a charge of 1+ and nitrogen forms a charge of 3-. To balance the charge, three cesium ions are needed to balance the charge of one nitride ion. |
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Which pair of elements can form an ionic compound? |
Barium and iodine can form an ionic compound. An ionic compound is composed of a cation (metal) and an anion (nonmetal or polyatomic ion). Barium and iodine are a metal and nonmetal, respectively, and can form an ionic compound. |
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