Advertisements
Advertisements
Question
Give reason
Actual atomic mass is greater than mass number.
Advertisements
Solution
Actual atomic mass is greater than the mass number because the mass number is a whole number approximation of atomic mass unit. In fact, neutrons are slightly heavier than protons, and an atom has over 200 sub-atomic particles.
APPEARS IN
RELATED QUESTIONS
TRUE \ FALSE
After the emission of a beta-particle, the atomic number of the atom increases by one.
WRITE SHORT ANSWER
Define the atomic mass number of an atom.
From the symbol `""_2^4"He"` for the element helium, write down the mass number and the atomic number of the element.
Match the statements in List I with the correct answer from List II.
| List I | List II |
| 1. Mass number of an atom is the number of protons and | A: Electron |
| 2. The sub-atomic particle with a negligible mass. | B: Argon |
| 3. An atom having stable electronic configuration. | C: Nitrogen |
| 4. A molecule formed by sharing of electrons [covalency] | D: Sodium |
| 5. A metallic atom having unstable electronic configuration. | E: Neutrons |
The diagram represents an isotope of hydrogen [H]. Answer the following:
Atomic no. = 1
Mass no. = 1
Are isotopes atoms of the same element or different elements.
Draw the structure of the following atoms showing the nucleus containing – protons, neutrons and the orbits with the respective electron:
Isotopes of hydrogen [11H, 21H, 31H]
The ratio of the radii of hydrogen atom and its nucleus is ~ 105. Assuming the atom and the nucleus to be spherical,
- what will be the ratio of their sizes?
- If atom is represented by planet earth ‘Re ’ = 6.4 ×106 m, estimate the size of the nucleus.
A ______ number describes a specific aspect of an electron.
‘A’ is denoted by ______.
Ca2+ has completely filled outer shell. Justify your answer.
