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Combined Science: Chemistry

GCSE · Edexcel · higher

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Group 1
- Group 1 (Alkali Metals)
  5
- Group 1: Reactivity & Electronic Configurations
  3
Group 7
Group 0

Relative Formula Mass Flashcards

All 3 cards in this deck

What is relative formula mass ( $M_r$ )?: The sum of the relative atomic masses of all the atoms shown in the formula of a substance.
What is the equation for the percentage by mass of an element in a compound?: % by mass = (total $A_r$ of that element's atoms in the formula ÷ $M_r$ of the compound) × 100
True or false? When finding the percentage by mass of hydrogen in $\mathrm{NH_3}$ , you use $3 \times 1.0$ as the mass of hydrogen.: True. You must use the mass of all the atoms of that element in the formula, not just one.