Structure of the Atom

Grade 9 Science — Structure of the Atom: 25 practice questions with instant scoring and explanations.

1. Thomson's model of the atom proposed that:
2. Rutherford's gold foil experiment showed that:
3. In Bohr's model of the hydrogen atom, electrons:
4. The nucleus of an atom contains:
5. Atomic number is defined as:
6. Mass number is the sum of:
7. An atom with 6 protons, 6 neutrons, and 6 electrons is:
8. Isotopes are atoms of the same element that have:
9. Carbon-12 and Carbon-14 are isotopes. What is the difference between them?
10. Isobars are atoms that have:
11. Chlorine has two main isotopes: Cl-35 and Cl-37. In nature, Cl-35 is more abundant. The average atomic mass of chlorine is:
12. An element with atomic number 8 has electrons:
13. The charge on a nucleus with 10 protons is:
14. Which pair consists of isobars?
15. The number of electrons in a neutral atom equals:
16. An ion with 8 protons and 10 electrons has a charge of:
17. The maximum number of electrons in the first shell is:
18. The maximum number of electrons in the second shell is:
19. A metal atom loses 2 electrons to form an ion. The ion will have a charge of:
20. Which of the following is TRUE about neutrons?
21. The relative mass of a proton compared to an electron is approximately:
22. Bohr's model was an improvement over Thomson's model because it:
23. An atom of nitrogen (atomic number 7) in its neutral state has electrons:
24. The mass of an atom is almost entirely due to:
25. Isotope notation ²⁴₁₂Mg indicates: