atomic number Flashcards
The velocity of photon is
Independent of its wavelength
Because the photons move with the speed of light so their velocity is independent of wavelength
The 3rd orbit of hydrogen atom is______ away from the nucleus as compare to first orbit
Distance of shell from nucleus given by 0.529n2Ao
1st shell ⟶ 0.529(1)2Ao = 0.529 Ao
3rd shell ⟶ 0.529(3)2Ao = 0.529 × 9 Ao
so, 9 times away than 1st shell
what is meant by isoelectronic
both ions/atom have the same no. of electrons
Which of the following quantum numbers describes energy of an electron in an atom?
Principal quantum number (n) provides information about the energy of the an electron in an atom.
It is also present in energy formula derived by Bohr.
E = 2.178 × 10-18 × [1/n2] J
formula for calculating radial nodes
Radial nodes = n – l – 1
for 4f orbital 4 – 3 – 1 = 0
Angular momentum of 2nd orbit is
Angular momentum is given by nh/2π. Since n=2 so it becomes h/π
With increase in value of principle quantum number ‘n’, the shape of ‘s’ orbital remains same although their sizes
n α size of ‘s’ orbital
so sizes increas
The charge of one gram of electron is
One electron mass is 9.109⨯10-28 g, so there are 1/(9.11⨯10-28) = 1.098⨯1027 electrons per gram. One electron charge is 1.602⨯10-19 C, so the charge of a gram of electrons is
(1.098⨯1027) (1.602⨯10-19) C = 1.759⨯108 C.
USEFUL TRICK: In the actual test use approximations to save time.
Mass of electron is 9⨯10-28 g so there are 1/(9⨯10-28) = 1⨯1027 electrons per gram. Multiple it with charge to get 1.6⨯108 C and the closest choice to this approximation is C.
Maximum number of electrons in an orbital of f-sub shell are
Orbital of any sub-shell can accommodate 2e– Only.
Which quantum number tells about the orientation of orbitals?
The magnetic quantum number determines the number of orbitals and their orientation within a subshell. Consequently, its value depends on the orbital angular momentum quantum number l. Given a certain l, ml is an interval ranging from –l to +l, so it can be zero, a negative integer, or a positive integer.
Which of the following quantum numbers determines number of orbitals in a sub-shell
Magnetic quantum number
The value of “m” gives us information of degeneracy of orbitals in space. The different values of ‘m’ represent total number of different space orientations for a sub-shell.
The atomic number of an element is 17. The number of orbits is?
3
the number of orbitals containing eclectrons in the valence shell is 3
as 3s2 and 3p5
For a given value of “l”, the total values of “m” are
(2l + 1)
The total number of electrons in a sub-shell can be determined by
2(2l + 1)
The number of orbitals in the fourth energy level is
16
n2
In a Multi-electron atoms, the energy of the electrons in a particular orbital is determined by
n + l
The divisibility of atom was showed by
JJ Thomson suggested that atoms are divisible and consist of negatively charged particles.
Angle of deflection in magnetic field was studied by
J. Perrin
1895
Charge of electron was measured by
Millikan
Who modified Bohr’s theory by introducing elliptical orbital for electron path
Sommerfield
the maximum possible number of electrons a shell n can accomadate by
2n squared
JJ thomson determined the
e/m value of electron
rls between n and L is?
L = n - 1
diameter of an atom
0.5 nm
value of rydberg constant
1.09678 x 10’ 7 m-1
in gases how many times is the distance greater than their diameters
300
the radius of an electron orbit in a hydrogen atom is of the order of
1 x 10 11th power meters
0.53 Armstrong
the mass of one mole of electrons is
0.54 mg
shielding effect is also called
screening effect
the number of atoms present in a molecule determines it’s
atomicity
how many times are hb molecules heavier than H atoms?
68,000
which of the following technique is used to measure the atomic radius
x ray anaylsis
magnetic quantum number of s is
zero
the presence of several fine lines in a line spectrum shows the presence of?
sub shells
which character of p-orbital determines the geometry of molecules
directional
the value of the principal quantum number n represent?
shells or energy levels
canal rays are produced in te discharge tube from
gas molecules in the tube
which experiment proved electron’s particle nature
paddlewheel/pinwheel
after 3d is filled next electron goes 4p according to
auf ba’s principle
electrons w same “m” quantum number prefered to be — according to —
Unpaired
Hund’s rule
no of orbitals in a shell formula
n^2
max no of transitions of excited atom formula
n(n-1)/2
when hydrogen gas is enclosed in a discharge tube using low pressure it emits
blue light
which atom does have spin quantum number 1/2
odd mass number and odd atomic number
as the attraction between the nucleus and the foreign electron increases, the P.E of the system
decreases
