Year 10 Forming and Balancing Equations Flashcards
(14 cards)
What is valency?
The combining power of an element.
Elements in the same group will have the same valency.
What must the total valency of a compound add up to?
Zero.
This is necessary for the compound to be stable.
What is the formula for Calcium oxide?
CaO.
Calcium has a valency of +2 and oxygen has a valency of -2.
How do you write the formula for Calcium chloride?
CaCl2.
The formula balances the valencies of calcium (+2) and chlorine (-1).
What are polyatomic ions?
Ions that contain more than one atom.
Examples include sulfate and hydroxide.
What is the formula for sodium nitrite?
NaNO2.
The compound adds to zero, so no bracket is needed.
What is the formula for calcium nitrate?
Ca(NO3)2.
A bracket is used because more than one nitrate ion is needed.
What is unique about transition metals regarding valency?
They can have more than one valency.
Roman numerals in the name indicate the specific valency.
What is the formula for iron (II) chloride?
FeCl2.
The (II) indicates that iron has a valency of +2.
How should a balanced equation be structured?
Reactants -> Products.
The number of atoms on each side must be the same.
What are the steps to balance a chemical equation?
- Count the number of atoms in reactants and products.
- Use balancing numbers to adjust.
- Never change a formula.
Balancing ensures the law of conservation of mass is obeyed.
What is the balanced equation for the reaction of CaCO3 and HCl?
CaCO3 + 2HCl -> CaCl2 + H2O + CO2.
Balancing numbers are used to ensure the same number of each atom on both sides.
True or False: The formula must be changed to balance an equation.
False.
Balancing is done by adding coefficients, not changing the formulas.
Fill in the blank: The aim is to get atoms to be _______.
even numbers first.
This helps in balancing the equation effectively.
