12 Questions
Which element has the symbol Mg2+?
Magnesium
What is the correct formula for iron (III) nitride?
Fe3N2
In compounds formed with polyatomic ions, where should the ion be placed in the chemical formula?
In a bracket before writing the number to indicate the ratio
What is the valency of Copper (II) in ionic compounds?
2+
What is the ratio by mass of magnesium to sulfur in magnesium sulphide?
3:4
How can valency be best described in relation to chemical compounds?
Valency is the combining power of an element that determines how it combines with other elements in a compound.
What would be the correct chemical formula for an octopus holding 8 humans based on the analogy provided?
O8H8
In the context of chemical compounds, how does valency relate to the number of arms or hands of an atom?
Valency represents the number of arms or hands an atom has for bonding with other atoms.
What is the correct order of writing when forming chemical formulas for compounds?
Write the symbol of cation first, followed by the symbol of anion
In magnesium chloride, why is the formula written as MgCl2?
There are two magnesium ions for each chloride ion
Why is it necessary to use brackets in the formula for calcium hydroxide?
To represent multiple hydroxyl groups attached to one calcium atom
How are the charges on ions represented in chemical formulas?
By placing charges outside the brackets
Study Notes
Chemical Compounds and Formulas
- Mg²⁺ is the symbol for magnesium ion.
Chemical Formula for Iron (III) Nitride
- The correct formula for iron (III) nitride is FeN.
Placement of Polyatomic Ions in Formulas
- In compounds formed with polyatomic ions, the ion should be placed after the symbol of the metal.
Valency of Copper (II)
- The valency of Copper (II) in ionic compounds is 2.
Ratio of Magnesium to Sulfur in Magnesium Sulphide
- The ratio by mass of magnesium to sulfur in magnesium sulphide is 1:1.
Valency in Relation to Chemical Compounds
- Valency can be best described as the number of electrons an atom gains or loses to form a stable compound.
Valency Analogy: Octopus Holding Humans
- The correct chemical formula for an octopus holding 8 humans would be Octo(Human)₈.
Valency and Atomic Arms or Hands
- Valency relates to the number of arms or hands of an atom, representing the number of electrons an atom can gain or lose to form a stable compound.
Order of Writing Chemical Formulas
- The correct order of writing chemical formulas for compounds is to write the symbol of the metal first, followed by the symbol of the non-metal.
Magnesium Chloride Formula
- The formula for magnesium chloride is written as MgCl₂ because magnesium has a valency of 2 and chlorine has a valency of 1.
Brackets in Calcium Hydroxide Formula
- Brackets are necessary in the formula for calcium hydroxide (Ca(OH)₂) to indicate that the OH group is a single unit.
Representation of Ion Charges in Formulas
- The charges on ions are represented in chemical formulas by writing the charge of the ion in superscript, e.g., Mg²⁺.
Test your knowledge of chemical symbols for elements and polyatomic ions. Learn the symbols for metals, nonmetals, and polyatomic ions with varying valencies.
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