Chemical formulae
Lesson 5 / 9
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Waxaan isticmaali karaa astaamaha kiimikada si aan u qoro qaaciidooyinka kiimikada ee curiyeyaasha iyo isku-dhisyada.
Introduction
In this lesson: I can use chemical symbols to write down chemical formulae for elements and compounds. The symbols for each element (each type of atom) a substance contains, appear in its chemical formula. Numbers (subscripts) next to chemical symbols in a formula show the numbers of each type of atom in a compound.
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Quizzes
1. Which of the following is a molecule?
- Na
- Correct answer:H₂O
- Mg
- Correct answer:NH₃
1. What does the chemical formula H₂O represent?
- Correct answer:Two hydrogen atoms and one oxygen atom.
- One hydrogen atom and two oxygen atoms.
- Two hydrogen molecules and one oxygen molecule.
- Two oxygen atoms and one hydrogen atom.
2. In the formula CO₂, what does the subscript '2' indicate?
- There are two carbon atoms.
- Correct answer:There are two oxygen atoms.
- The compound is twice as heavy as oxygen.
- The compound is twice as reactive.
3. What is the difference between H₂O and H₂O₂?
- H₂O₂ has more hydrogen atoms.
- H₂O has more oxygen atoms.
- Correct answer:H₂O₂ has more oxygen atoms.
- H₂O has more hydrogen atoms.
- There's no difference. They have the same number of oxygen and hydrogen atoms.
4. Which statement best defines a chemical formula?
- A description of a chemical reaction.
- A graphical representation of a molecule.
- Correct answer:A symbolic way to represent the elements in a chemical substance.
- A method to determine the pH of a substance.
What pupils see
The same lesson as a pupil sees it. You can set any section as work on its own.
- IntroductionPrepare
- Starter quizActivate · 1 question
- Lesson videoLearn
- Exit quizCheck · 4 questions