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Different atoms have different numbers of sub-atomic particles - AQA - GCSE Chemistry - Question 3 - 2016 - Paper 2
Question 3
Different atoms have different numbers of sub-atomic particles. 3 (a) (i) An oxygen atom can be represented as \(^{16}_8 O\). Explain why the mass number of this a... show full transcript
Worked Solution & Example Answer:Different atoms have different numbers of sub-atomic particles - AQA - GCSE Chemistry - Question 3 - 2016 - Paper 2
Step 1
Explain why the mass number of this atom is 16.
Answer
The mass number of an atom is calculated as the total number of protons and neutrons in its nucleus. In the case of the oxygen atom represented as (^{16}_8 O), it has 8 protons and 8 neutrons. Thus, the mass number is given by:
This is why the mass number of this oxygen atom is 16.
Step 2
Explain why \(^{12}_6 C\) and \(^{14}_6 C\) are isotopes of carbon.
Answer
The isotopes (^{12}_6 C) and (^{14}_6 C) are both forms of carbon that have the same number of protons, which is 6 in this case. However, they differ in the number of neutrons: (^{12}_6 C) has 6 neutrons while (^{14}_6 C) has 8 neutrons. Isotopes are defined as atoms of the same element that have the same atomic number (protons) but different mass numbers due to differing numbers of neutrons.
Step 3
Complete Figure 3 to show the arrangement of the outer shell electrons of the hydrogen and oxygen atoms in a molecule of water.
Answer
In a water molecule (H₂O), the oxygen atom has 6 outer shell electrons, and each hydrogen atom contributes 1 outer shell electron. Therefore, the arrangement would show:
- 2 hydrogen atoms, each with 1 • representing their outer shell electrons.
- The oxygen atom in the center with 4 unbonded electrons (• •) and 2 bonding pairs with the hydrogen atoms.
Step 4
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Step 6
How does the size of a nanoparticle compare with the size of an atom?
Answer
Nanoparticles are generally larger than individual atoms. While an individual atom typically has a size on the order of a few angstroms (1 Å = 10^{-10} m), nanoparticles can range from a few nanometers (1 nm = 10^{-9} m) to several hundred nanometers. Therefore, nanoparticles can be composed of many atoms and have larger sizes than single atoms.
Step 7
Suggest one reason why 1 g of cobalt oxide nanoparticles is a better catalyst than 1 g of cobalt oxide powder.
Answer
One reason is that cobalt oxide nanoparticles have a larger surface area compared to cobalt oxide powder. A larger surface area allows for more active sites for chemical reactions, which enhances the catalytic activity of the nanoparticles.