chemistry Flashcards
Who was the first person to assign chemical symbols to the different atoms?
Dalton.
Define Element
An element is a substance that cannot be broken down into simpler substances by chemical reactions.
Define Compound
Is a substance made up by chemically combining two or more elements.
It has different properties from its constituent elements.
Who pictured ‘‘PLUM PUDDING’’ model?
J.J.Thomson
the negatively charged electrons scattered in positively charged sponge like substance.
The alpha particles are………………………………….
Helium nuclei,composed of two p and two n with a positive charge.
Conclusion of Rutherford experiment are ?
The large no of deflected particles led to the conclusion that the atom is mainly empty space.
1] Nuclear Radius
2] Atomic Radius
1] 10^-15 m
2] 10^-10 m
Importance of the NEUTRONS.
Neutrons are crucial for the stability of the nuclei.
Because without neutrons protons will repel each other and nucleus would fall apart.
Define Isotopes
Atoms of the same element with the different numbers of neutrons are called isotopes. Because atomic number is same because it has to be the same element .
- same element with different mass number.
Does isotopes has the same chemical properties ?
Yes because different number of neutrons doesn’t make difference how they react so they occupy same place in the periodic table.
Refer pg no 64
Does Isotopes affects physical properties?
Yes difference in mass affects physical proprties such as BP & MP.
ow to separate the isotopes?
Heavier isotopes move slower hence easy to differentiate.
Chlorine isotopes
Cl-35(abundant)
Cl-37
The number of protons and neutrons never change in chemical reactions.
true/false ?
1] then which is responsible for the change in the chemical reactions ?
TRUE
1] Electrons
Define Ions
Atoms can lose or gain electrons to form ions.
Full spectrum
Ranges from low energy radio waves to high energy gamma waves .
All electromagnetic waves travel at the same speed .
TRUE/FALSE ?
Red has the highest wavelength.
TRUE, but they have different wavelength.
[different colors of visible light have different wavelength]
Define frequency
The number of waves which pass a particular point in 1 s is called frequency.
Relation between frequency and wavelength
Inversely proportional .
hence blue light has the higher frequency than the red light.
[where c is the speed of light]
Prism produces ……………..
Continuous spectrum
Spectrum
Visible light emits infrared radiations,which has longer wavelength than red light,
UV radiations,with shorter wavelength than violet light.
[REFER PG NO 71]
1.Absorption of radiation……..
Uses to excite the atoms from lower energy level to higher energy level.
[excited state is unstable ]
The energy that electron gives out when it falls into lower levels is in the form of ?
Electromagnetic radiations
one packet of energy [quantum] or photon is released for each electron transition. TRUE/FALSE?
TRUE
UV photon > Infrared light Photon [energy ]
True
The energy of photon is proportional to the ……………………
frequency of the radiations
When an atom falls from excited state to the ground state,light of specific frequency v is emitted.
When an atom moves from the ground state to an excited state,light of specific frequency v is absorbed.
E = h ν
Refer pg no 72
The electron cannot change its energy in continuous way . TRUE/FASLE
TRUE because it can change only in discrete amts.
The energy of atom is QUANTIZED.
Refer pg no 72 & 71
1]Diffraction………………………..
2]Scattering of electrons………………………….
1] Wave
2]Particle
The shape of the orbital depends upon ?
The energy of electron.
Higher the energy ………………….
Farther from the nucleus.
The transition from n=1 to n =infinite corresponds to
Ionization
Energy level converge at
Highers energy
There is a increase in successive Ionization energy .
TRUE/FALSE
TRUE
