GCSE - General Certificate of Secondary Education Atomic Structure & Periodic Table Questions and Answers — Questions and Answers
Question 1: An atom has an atomic number of 11 and a mass number of 23. How many protons, neutrons, and electrons are in this atom?
- 12 protons, 11 neutrons, 11 electrons
- 11 protons, 12 neutrons, 11 electrons (Correct answer)
- 11 protons, 11 neutrons, 12 electrons
- 12 protons, 12 neutrons, 11 electrons
Correct answer: 11 protons, 12 neutrons, 11 electrons
The atomic number represents the number of protons. In a neutral atom, the number of electrons is equal to the number of protons. The mass number is the sum of protons and neutrons, so to find the number of neutrons, you subtract the atomic number from the mass number (23 - 11 = 12).
Question 2: Which of the following statements correctly describes isotopes?
- Atoms of the same element with a different number of protons but the same number of neutrons.
- Atoms of different elements with the same number of neutrons.
- Atoms of the same element with the same number of protons but a different number of electrons.
- Atoms of the same element with the same number of protons but a different number of neutrons. (Correct answer)
Correct answer: Atoms of the same element with the same number of protons but a different number of neutrons.
Isotopes are defined as atoms of the same element that have the same number of protons (and thus the same atomic number) but different numbers of neutrons. This results in them having different mass numbers.
Question 3: An element is located in Group 17 (or Group 7) of the periodic table. Which of the following properties is it most likely to have?
- It is a soft, highly reactive metal.
- It has a full outer shell of electrons and is unreactive.
- It forms a +1 ion when it reacts.
- It has 7 electrons in its outer shell and is a reactive non-metal. (Correct answer)
Correct answer: It has 7 electrons in its outer shell and is a reactive non-metal.
Elements in Group 17 are the halogens. They are characterized by having 7 electrons in their outer shell. This makes them highly reactive non-metals, as they tend to gain one electron to achieve a stable, full outer shell.
Question 4: A scientist discovers a new element with the electron configuration 2, 8, 5. In which period and group of the periodic table would this element be placed?
- Period 3, Group 5 (or 15) (Correct answer)
- Period 2, Group 8
- Period 5, Group 3
- Period 3, Group 2
Correct answer: Period 3, Group 5 (or 15)
The number of electron shells (in this case, three: 2, 8, 5) determines the period number, so it is in Period 3. The number of electrons in the outermost shell (5) determines the group number for main group elements, placing it in Group 15 (or 5).
Question 5: Which statement best describes the development of the modern periodic table?
- John Dalton arranged the elements in order of increasing atomic mass and chemical properties.
- Dmitri Mendeleev arranged the elements strictly by atomic mass, which resulted in a perfect ordering.
- Henry Moseley's work on atomic numbers led to the elements being arranged in order of increasing atomic number, resolving inconsistencies in Mendeleev's table. (Correct answer)
- J.J. Thomson arranged the elements based on the discovery of the electron.
Correct answer: Henry Moseley's work on atomic numbers led to the elements being arranged in order of increasing atomic number, resolving inconsistencies in Mendeleev's table.
While Mendeleev did amazing work by arranging elements by atomic mass and leaving gaps for undiscovered elements, his table had some inconsistencies. Henry Moseley later discovered that arranging elements by their atomic number (the number of protons) created a more accurate and consistent periodic table.
Question 6: What are the relative charges of a proton, neutron, and electron?
- Proton: 0, Neutron: +1, Electron: -1
- Proton: +1, Neutron: -1, Electron: 0
- Proton: +1, Neutron: 0, Electron: -1 (Correct answer)
- Proton: -1, Neutron: 0, Electron: +1
Correct answer: Proton: +1, Neutron: 0, Electron: -1
The standard relative charges for the subatomic particles are: proton is +1, neutron is neutral (0), and electron is -1. These charges are relative to each other.
GCSE - General Certificate of Secondary Education Atomic Structure & Periodic Table Questions and Answers
An atom has an atomic number of 11 and a mass number of 23.
How many protons, neutrons, and electrons are in this atom?