structure of atom Flashcards
(22 cards)
it was known by 1900 that the atom was an indivisible particle which contained atleast one subatomic particle. what was this and who was it identified by?
electron identified by JJ thomson
what are canal rays?
E. goldstein in 1886 discovered the presence of new radiations in a gas discharge and called them canal rays . they were positively charged radiations.
what is the mass of a proton with respect to an electron?
2000 times that of electron
what is the charge and mass of electron?
mass of an electron is considered negligible and its charge is -1
Who was the first to propose a model for the structure of an atom?
JJ thomson
What is the radius of a nucleus with respect to that of an atom?
about 10^5 less than that of the atom
Who first discovered neutrons?
J. Chadwick
what is the charge and mass of neutron?
a neutron has no charge and a mass nearly equal to that of a proton.
what are the symbols for proton, electron and neutron respectively?
p^+ , e^- , n
Neutrons are present in the nucleus of all atoms, with the exception of _
hydrogen
who suggested the distribution of electrons into different orbits of atoms?
Bohr and Bury
what are valence electrons?
the electrons present in the outermost shell of atoms
what causes a substance to have a combining capacity?
the tendency of atoms to react and form molecules was explained as an attempt to attain a fully filled outermost shell (which would make them inert).
what is octet?
an outermost shell with 8 electrons is said to possess an octet.
how is valency of an element found?
it is the number of electrons gained or lost in an atom in order to make an octet in its outermost shell.
what is atomic number and what is it denoted by?
The total number of protons present in the nucleus of an atom gives its atomic mass. It is denoted by “Z”.
what are protons and neutrons collectively called?
nucleons
what is mass number and what is it denoted by ?
the sum of total number of protons and neutrons present in the nucleus of an atom is its mass number. it is denoted by”A”.
what are isotopes?
isotopes are defined as the atoms of the same element having the same atomic number but different mass numbers.
name the three isotopes of hydrogen.
protium, deuterium, tritium
pg 52 learn isotopes of carbon
learnt
what are isobars?
atoms of different elements with different atomic numbers but same mass numbers are called isobars.
