Advertisements
Advertisements
प्रश्न
What are the atomic numbers of elements whose outermost electrons is represented by 3s1.
उत्तर
3s1
Completing the electron configuration of the element as
1s2 2s2 2p6 3s1.
∴ Number of electrons present in the atom of the element
= 2 + 2 + 6 + 1 = 11
∴ Atomic number of the element = 11
APPEARS IN
संबंधित प्रश्न
With the help of given Table, find out the mass number of sulphur atom.
| Composition of Atoms of the First Eighteen Elements with Electron Distribution in Various Shells | ||||||||||
| Name of Element | Symbol | Atomic Number | Number of protons | Number of Neutrons | Number of Electrons | Distribution of Electrons | Valency | |||
| K | L | M | N | |||||||
| Hydrogen | H | 1 | 1 | - | 1 | 1 | - | - | - | 1 |
| Helium | He | 2 | 2 | 2 | 2 | 2 | - | - | - | 0 |
| Lithium | Li | 3 | 3 | 4 | 3 | 2 | 1 | - | - | 1 |
| Beryllium | Be | 4 | 4 | 5 | 4 | 2 | 2 | - | - | 2 |
| Boron | B | 5 | 5 | 6 | 5 | 2 | 3 | - | - | 3 |
| Carbon | C | 6 | 6 | 6 | 6 | 2 | 4 | - | - | 4 |
| Nitrogen | N | 7 | 7 | 7 | 7 | 2 | 5 | - | - | 3 |
| Oxygen | O | 8 | 8 | 8 | 8 | 2 | 6 | - | - | 2 |
| Fluorine | F | 9 | 9 | 10 | 9 | 2 | 7 | - | - | 1 |
| Neon | Ne | 10 | 10 | 10 | 10 | 2 | 8 | - | - | 0 |
| Sodium | Na | 11 | 11 | 12 | 11 | 2 | 8 | 1 | - | 1 |
| Magnesium | Mg | 12 | 12 | 12 | 12 | 2 | 8 | 2 | - | 2 |
| Aluminium | Al | 13 | 13 | 14 | 13 | 2 | 8 | 3 | - | 3 |
| Silicon | Si | 14 | 14 | 14 | 14 | 2 | 8 | 4 | - | 4 |
| Phosphorus | P | 15 | 15 | 16 | 15 | 2 | 8 | 5 | - | 3.5 |
| Sulphur | S | 16 | 16 | 16 | 16 | 2 | 8 | 6 | - | 2 |
| Chlorine | Cl | 17 | 17 | 18 | 17 | 2 | 8 | 7 | - | 1 |
| Argon | Ar | 18 | 18 | 22 | 18 | 2 | 8 | 8 | 0 | |
Multiple Choice Questions
The sum of number of protons and number of neutrons present in the nucleus of an atom is called its
What are the two main features of Rutherford’s atomic model?
TRUE \ FALSE
After the emission of a beta-particle, the atomic number of the atom increases by one.
Fill in the following blanks :
| Atomic Number | Mass Number | Protons | Neutrons | Electrons | Symbol |
| 10 | 22 | _________ | _________ | _________ | _________ |
From the symbol `""_15^31"P"`, state :
(i) mass number of phosphorus,
(ii) atomic number of phosphorus, and
(iii) electron configuration of phosphorus.
The atom of an element X has 7 electrons in its M shell.
What is the atomic number of element X?
The properties of the elements are a periodic function of their __________.
From the symbol `""_2^4"He"` for the element helium, write down the mass number and the atomic number of the element.
Draw the atomic diagram of the following element showing the distribution of – protons, neutrons and the electrons in the various shell of the atom.
Calcium – \[\ce{^40_20Ca}\]
[The upper number represent the – mass number and the lower number represent the – atomic number e.g. calcium – mass number = 40, atomic number = 20]
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
Do isotopes have the same atomic number or the same mass number?
Draw the structure of the following atoms showing the nucleus containing – protons, neutrons and the orbits with the respective electron:
Lithium [At. no. = 3, Mass no. = 7]
What are nucleons? How many nucleons are present in Phosphorous? Draw its structure.
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.
The particles that make up the atom are called ______ particles.
______ = No. of protons = No. of the electrons.
Match the following:
| Column A | Column B | ||
| 1. | Mass of proton | a. | +1 |
| 2. | Mass of electron | b. | -1 |
| 3. | Charge of electron | c. | 9.31 x 10-28g |
| 4. | Charge of proton | d. | 1.67 x 10-24g |
What is the relation between mass number & atomic number?
