Atomic Structure

Fill in the Blanks | Science | Class 9

1. The _ is a positively charged subatomic particle found in the nucleus.
2. The _ is a neutrally charged subatomic particle found in the nucleus.
3. Electrons are located in energy levels or _ around the nucleus.
4. The total number of protons in an atom is called the _ number.
5. The total number of protons and neutrons in an atom is called the _ number.
6. The _ of an element is determined by the number of protons in its nucleus.
7. Isotopes of an element have the same number of _ but a different number of neutrons.
8. The atomic mass of an element is typically given in _.
9. Electrons in the outermost energy level are called _ electrons.
10. The maximum number of electrons that can be accommodated in the first energy level is _.
11. The maximum number of electrons that can be accommodated in the second energy level is _.
12. The atomic number of oxygen is _.
13. An atom with 8 protons and 10 neutrons has an atomic mass of _.
14. The chemical symbol for sodium is _.
15. The number of electrons in a neutral sodium atom is _.
16. The electrons in the outermost energy level are involved in _.
17. A cation is formed when an atom loses _.
18. Anions are formed when atoms gain _.
19. The nucleus of an atom contains nearly all of its _.
20. The subatomic particles that have approximately the same mass are protons and _.