Elements are made of atoms - AQA - GCSE Chemistry - Question 1 - 2017 - Paper 1
Question 1
Elements are made of atoms.
Table 1 shows the atomic numbers and mass numbers of three atoms.
Table 1
| Atom | Atomic number | Mass number |
|------|-------------... show full transcript
Worked Solution & Example Answer:Elements are made of atoms - AQA - GCSE Chemistry - Question 1 - 2017 - Paper 1
Step 1
Suggest, in terms of the number of subatomic particles, why the atomic numbers of the three atoms are the same.
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Answer
The atomic numbers of the three atoms are the same because they all have the same number of protons in their nuclei, specifically 12 protons each.
Step 2
Explain, in terms of the number of subatomic particles, why the mass numbers of the three atoms are different.
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Answer
The mass number is the total count of protons and neutrons in an atom's nucleus. Since all three atoms have 12 protons, the difference in mass numbers (24, 25, 26) is due to the varying numbers of neutrons present. Specifically, the first atom has 12 neutrons, the second has 13 neutrons, and the third has 14 neutrons.
Step 3
How many elements are in the formula H₂SO₄?
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There are 3 elements in the formula H₂SO₄: hydrogen (H), sulfur (S), and oxygen (O).
Step 4
How many atoms are in the formula H₂SO₄?
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There are 7 atoms in the formula H₂SO₄, consisting of 2 hydrogen atoms, 1 sulfur atom, and 4 oxygen atoms.
Step 5
What is the mass of the products? Tick (✓) one box.
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Answer
The mass of the products is 319 g (CuSO₄) and 36 g (H₂O).
Step 6
Describe and explain the changes seen during the reaction.
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Answer
During the reaction, the solution changes as follows: limewater turns cloudy indicating the presence of carbon dioxide, the solution in the apparatus decreases in mass as the copper carbonate is consumed, and the copper carbonate (green solid) disappears. The reaction may also produce bubbles, indicating effervescence, as carbon dioxide gas is produced.
