The first use of quantum theory to explain the structure of atom was made by –
Plum-Pulding model is known as–
Thomson proposed the plum pudding model of the atom, which had negatively-charged electrons embedded within a positively-charged "soup." Rutherford's gold foil experiment showed that the atom is mostly empty space with a tiny, dense, positively-charged nucleus.
Nucleous consist of–
The number of valence electron in Na is –
we know , the atomic no. Of Na:- 11 , so , the first shell is filled with two electrons, the 8 electrons are filled in the second shell , thus there is one electron left.
So, there is only one valence electron in Na.
Mass number of element is –
The mass number, also called atomic mass number or nucleon number, is the total number of protons and neutrons in an atomic nucleus. It is approximately equal to the atomic mass of the atom expressed in atomic mass units.
According to the Dalton's atomic theory –
Neutron is a fundamental particle which have–
No. of unpaired electron in 1s2.2s2.2p4
Hund's rule says , when electrons are filled in orbitals of equal energy, one electron enters each orbital until all the orbitals contain one electron with the same spin direction. Then the pairing of electrons take place.
Thus in electronic configuration, the electrons in p subshell are filled in 3 orbitals such that every orbital contains one electron each. The fourth electron will be paired up with the first electron and the other two electrons remain unpaired.
The electron should be filled in the orbital in accordance with the increasing order of their energy. This statement
is related with
This statement is related with Aufbau principle.
According to Aufbau principle (also known as (n+l) rule), electrons are filled in different orbitals from lower (n+l) value orbital to higher (n+l) value orbital.
In case (n+l) value is same, electron is filled first in orbital with lower value of n.
Which species does not contain neutron –
In an atom, the mass number of an atom is equal to the number of___________.
Atomic number of any element–
Atomic number = atomic weight / 2
Atomic no. Of Ca( 20) :-
atomic weight (40) /2
Lighest particle is –
Fundamental particle of atomic nucleus is–
The nucleus of an atom consists of neutrons and protons, which in turn are the manifestation of more elementary particles, called Quark. That is held in association by the nuclear strong force in a certain stable combination of hadrons, called baryons.
The atomic size of atom is nearly –
The atom is about 10-10 meters (or 10-8 centimeters) in size. This means a row of 10^8 (or 100,000,000)atoms would stretch a centimeter, about the size of your fingernail. Atoms of different elements are different sizes, but 10-10 m can be thought of as a rough value for any atom.
An atom which has a mass number of 14 or 8 neutrons is–
Isotopes are the atoms of the same element with similar atomic number but different atomic mass.The elements of isotopes share same chemical properties but different physical properties
Electronic configuration of p in ground state is –
The ground state electron configuration of ground state gaseous neutral phosphorus is [Ne]. 3s².3p³
When a gas at reduced pressure is subjected to an electric discharge, the rays orignating from the negative electrode are–
Cathode ray, stream of electrons leaving the negative electrode (cathode) in a discharge tube containing a gas at low pressure, or electrons emitted by a heated filament in certain electron tubes. Cathode rays focused on a hard target (anticathode) produce X-rays or focused on a small object in a vacuum generate very high temperatures (cathode-ray furnace). When cathode rays strike certain molecules used to coat a cathode screen, they cause the molecules (and hence the screen) to emit light.
The maximum number of electrons that can be accomodate in the nth level is–
Isotopes of an element are the atom which have –
The nucleus of an atom contains:
What is the no. of electrons in Argon?
The no. of electrons is the atomic number of an element.
The isotope deuterium of hydrogen has
The other stable hydrogen isotope is known as deuterium and contains one proton and one neutron in its nucleus. The nucleus of deuterium is called a deuteron.
The no. of electrons in the valence shells of Sodium and Calcium repectively:
Electronic configuration of
Na is 2, 8, 1
Ca is 2, 8, 8, 2
The maximum number of electrons that can be accommodated in third shell ( n = 3) is: