Structure of Atoms Flashcards
(10 cards)
Key points of John Dalton’s Atomic Theory (1804)
What are all matters made of according to Dalton? A) Electrons B) Protons C) Atoms D) Molecules
What are atoms of the same element like, according to Dalton? A) They are all the same B) They are all different C) They are isotopes D) They are reactive
According to Dalton, how are atoms of different elements? A) Identical B) The same in all ways C) Different D) Mixed
What did Dalton say about creation and destruction of atoms? A) They can be created B) They can be destroyed C) They can be changed D) Neither created nor destroyed
What can atoms do in a chemical reaction according to Dalton? A) Form radiation B) Take part C) Get destroyed D) Lose mass
How are compounds formed as per Dalton’s theory? A) By melting solids B) By combining atoms C) By evaporating liquids D) By splitting molecules
Drawbacks of Dalton’s Atomic Theory
What was discovered about atoms that proved they are divisible? A) They are small B) They contain protons, neutrons, and electrons C) They can melt D) They weigh less than hydrogen
What do we call atoms of the same element with different mass and density? A) Isomers B) Isotopes C) Isobars D) Ions
Chlorine has two isotopes with mass numbers: A) 30 and 35 B) 32 and 34 C) 35 and 37 D) 36 and 38
Atoms of different elements having the same atomic mass are called: A) Isotopes B) Isomers C) Isobars D) Electrons
Which pair of elements are examples of isobars? A) Argon and Sodium B) Argon and Calcium C) Potassium and Calcium D) Calcium and Neon
What does Dalton’s theory fail to explain about carbon forms? A) Bonding B) Isotopes C) Isobars D) Allotropes like graphite and diamond
Merits of Dalton’s Atomic Theory
What does Dalton’s atomic theory help explain? A) Atomic number B) Chemical bonding C) Laws of chemical combination D) Molecular shape
What did Dalton clearly distinguish for the first time? A) Metals and non-metals B) Atoms and molecules C) Solids and gases D) Electrons and protons
C) Atoms
A) They are all the same
C) Different
D) Neither created nor destroyed
B) Take part
B) By combining atoms
B) They contain protons, neutrons, and electrons
B) Isotopes
C) 35 and 37
C) Isobars
B) Argon and Calcium
D) Allotropes like graphite and diamond
C) Laws of chemical combination
B) Atoms and molecules
Discovery of the Electron
Cathode Rays
Who discovered the electron using a cathode ray tube? A) J.J. Thomson B) Rutherford C) Bohr D) Chadwick
In which year did the discovery of the electron occur? A) 1885 B) 1897 C) 1905 D) 1911
What kind of particle is the electron according to J.J. Thomson’s experiment? A) Heavy neutral particle B) Positively charged particle C) Massless particle D) Negatively charged particle
What is the charge of an atom overall? A) Positive B) Neutral C) Negative D) Double
Are electrons found in all atoms? A) Only in gases B) No C) Yes D) Only in metals
What balances the negative charge of electrons in an atom? A) Neutrons B) Protons C) Energy D) Magnetic fields
What is seen when high voltage current passes through a gas at very low pressure? A) Red light B) Green fluorescence C) Bubbles D) Blue haze
Where do cathode rays come from? A) From anode B) From outside C) From cathode (negative plate) D) From vacuum
What are cathode rays made of? A) Atoms B) Electrons C) Protons D) Light waves
Who studied the properties of cathode rays? A) Bohr B) J.J. Thomson C) Maxwell D) Goldstein
A) J.J. Thomson
B) 1897
D) Negatively charged particle
B) Neutral
C) Yes
B) Protons
B) Green fluorescence
C) From cathode (negative plate)
B) Electrons
B) J.J. Thomson
Discovery of the Electron
Cathode Rays – Conclusions and Thomson’s Model
What are cathode rays made of? A) Positively charged particles B) Neutral gas atoms C) Negatively charged particles (electrons) D) Protons
Do electrons from different sources have the same mass? A) No B) Yes C) Sometimes D) Only in metals
What are electrons in terms of atom structure? A) Found in gases only B) Not part of atoms C) Constituent part of all atoms D) Not related to matter
What is the charge of an electron? A) +1.602×10⁻¹⁹ C B) -1.602×10⁻¹⁹ C C) -9.108×10⁻³¹ C D) +1.602×10⁻²⁰ C
What is the mass of an electron relative to a hydrogen atom? A) 1/1836 B) 1/1837 C) 1/1838 D) 1/1840
What is the actual mass of an electron? A) 9.108×10⁻³⁰ kg B) 9.108×10⁻³¹ kg C) 1.673×10⁻²⁷ kg D) 1.602×10⁻¹⁹ kg
What is the approximate radius of an electron? A) Less than 1×10⁻¹³ m B) Less than 1×10⁻¹⁶ m C) Less than 1×10⁻¹⁵ m D) Less than 1×10⁻¹² m
What is the idea behind Thomson’s “plum pudding” model? A) Electrons orbit the nucleus in shells B) Electrons are like plums in a positively charged “pudding” C) Electrons are in a dense nucleus D) Electrons are outside the atom
C) Negatively charged particles (electrons)
B) Yes
C) Constituent part of all atoms
B) -1.602×10⁻¹⁹ C
B) 1/1837
B) 9.108×10⁻³¹ kg
C) Less than 1×10⁻¹⁵ m
B) Electrons are like plums in a positively charged “pudding”
Discovery of the Electron
Rutherford’s gold foil experiment and Rutherford’s atomic model
What model did Rutherford use for his gold foil experiment? A) Nuclear model B) Bohr’s model C) Plum pudding model D) Planetary model
According to the Plum pudding model, what was expected in Rutherford’s experiment? A) Most alpha particles would bounce back B) Alpha particles would stop at the foil C) Alpha particles would pass straight through D) Alpha particles would ionize air
What result did Rutherford actually observe? A) All alpha particles bounced back B) Most alpha particles passed through; few were deflected C) Alpha particles got absorbed D) No particles passed through
What did Rutherford’s experiment prove? A) Atoms are solid B) Electrons are in shells C) Most of the atom is empty space D) Atoms have equal charge distribution
What is the name of the atom model proposed by Rutherford? A) Electron shell model B) Nuclear atom model C) Classical atom model D) Quantum model
What does Rutherford’s model say about the atom’s mass and charge? A) Spread out in space B) Evenly mixed C) Concentrated in the nucleus D) Outside the nucleus
In Rutherford’s model, where are the positive charges? A) In shells B) In orbitals C) Scattered D) In the nucleus
How do electrons move according to Rutherford’s model? A) In elliptical orbits B) In circular orbits around the nucleus C) Randomly D) In shells with fixed energy
What force pulls electrons toward the nucleus? A) Magnetic force B) Nuclear force C) Gravitational force D) Electrostatic attraction
What force balances the attraction between electrons and nucleus? A) Gravitational force B) Electrostatic repulsion C) Centrifugal force from electron motion D) Magnetic repulsion
C) Plum pudding model
C) Alpha particles would pass straight through
B) Most alpha particles passed through; few were deflected
C) Most of the atom is empty space
B) Nuclear atom model
C) Concentrated in the nucleus
D) In the nucleus
B) In circular orbits around the nucleus
D) Electrostatic attraction
C) Centrifugal force from electron motion
Discovery of the Electron
Rutherford’s gold foil experiment and Rutherford’s atomic model – Limitations
Questions:
Rutherford’s atomic model is based on which scientific laws? A) Newton’s Laws B) Kepler’s Laws C) Coulomb’s Law D) Boyle’s Law
Who identified the limitations of Rutherford’s atom model? A) J.J. Thomson B) Bohr C) Chadwick D) Dalton
According to the first limitation, which laws can apply only to neutral bodies like planets? A) Coulomb’s Laws B) Newton’s Laws C) Faraday’s Laws D) Avogadro’s Laws
What do planets do because of gravitational forces? A) Repel each other B) Remain stationary C) Attract each other D) Explode
What type of attraction exists in the nuclear atom model? A) Magnetic attraction B) Gravitational attraction C) Electrostatic attraction D) Nuclear fusion
According to Maxwell’s theory, a charged body like an electron must: A) Remain motionless B) Absorb energy C) Radiate energy continuously D) Orbit randomly
What happens to the speed of an electron if it radiates energy continuously? A) Increases B) Doubles C) Decreases D) Stops completely
If an electron loses speed, what happens to its orbit radius? A) Increases B) Becomes infinite C) Decreases D) Stays constant
What is the final result if the electron keeps losing energy and the orbit shrinks? A) Electron turns into neutron B) Atom becomes ionized C) Electron falls into nucleus D) Electron disappears
What is the main weakness of Rutherford’s atomic model? A) It describes orbit shapes poorly B) It cannot explain bonding C) It leads to atom collapse D) It ignores neutrons
What key detail was not given by Rutherford in his model? A) Mass of electrons B) Orbit shapes or sizes C) Chemical reactivity D) Number of protons
Answers:
A) Newton’s Laws
B) Bohr
B) Newton’s Laws
C) Attract each other
C) Electrostatic attraction
C) Radiate energy continuously
C) Decreases
C) Decreases
C) Electron falls into nucleus
C) It leads to atom collapse
B) Orbit shapes or sizes
Bohr’s atom model
Questions:
What kind of orbits are present in an atom according to Bohr?
A) Random paths
B) Elliptical orbits
C) Stable circular orbits
D) Parabolic curves
What are stable orbits also called?
A) Shells
B) Quantum rings
C) Energy levels
D) Radial paths
How are these orbits named based on their position?
A) Primary, secondary, tertiary
B) 1st, 2nd, 3rd energy levels
C) Kinetic zones
D) Alpha, beta, gamma
What happens to the energy as the electron’s orbit gets farther from the nucleus?
A) It decreases
B) It stays the same
C) It increases
D) It drops to zero
What type of energy do electrons have in these orbits?
A) Fixed energy with radiation
B) Random quantum energy
C) Integral multiple of hν without radiation
D) Variable energy
What is the closest shell to the nucleus called?
A) L shell B) M shell C) N shell D) K shell
Which shell is the third energy level? A) L B) M C) K D) N
What is the order of energy levels from lowest to highest?
A) E₃ < E₂ < E₁ B) E₁ < E₂ < E₃ C) E₂ < E₁ < E₃ D) E₁ = E₂ = E₃
What is Bohr’s condition for angular momentum of electrons?
A) mvr = nh B) mvr = 2πn C) mvr = n(h/2π) D) mvr = h/n
In the formula mvr = n(h/2π), what does ‘m’ represent?
A) Mass of nucleus B) Mass of electron C) Magnetic field D) Number of orbits
What does ‘v’ represent in mvr = n(h/2π)?
A) Voltage B) Volume C) Velocity of electron D) Vector direction
What does ‘r’ represent in the angular momentum formula?
A) Radius of orbit B) Resistance C) Reaction time D) Relative position
What does ‘h’ represent in Bohr’s equation?
A) Helium constant
B) Height of orbit
C) Planck’s constant
D) Hydrogen energy
What does ‘n’ represent in the angular momentum formula?
A) Neutron number B) Number of protons C) Principal quantum number
D) Atomic number
What is ‘n’ called in Bohr’s model? A) Quantum zone B) Orbital label
C) Principal quantum number D) Shell rank
C) Stable circular orbits
C) Energy levels
B) 1st, 2nd, 3rd energy levels
C) It increases
C) Integral multiple of hν without radiation
D) K shell
B) M
B) E₁ < E₂ < E₃
C) mvr = n(h/2π)
B) Mass of electron
C) Velocity of electron
A) Radius of orbit
C) Planck’s constant
C) Principal quantum number
C) Principal quantum number
Bohr’s atom model
Postulate concerning radiation of energy
What happens when an electron jumps from one orbit to another? A) Nothing happens B) Light is absorbed only C) Atom emits or absorbs energy D) Atom gains a proton
When does an atom radiate energy as light? A) When an electron goes to a higher level B) When a neutron is added C) When an electron goes from higher to lower level D) When the atom vibrates
What causes dark lines in a spectrum according to Bohr? A) Heating the atom B) Neutron collisions C) Electron jumping to higher level with energy absorption D) Atom cooling down
The energy emitted or absorbed equals: A) Zero B) The difference in energies before and after orbit change C) The energy in nucleus D) A multiple of atom’s mass
Bohr’s atom model
What is the equation for energy difference when an electron moves from higher to lower energy level? A) E₂ – E₁ = hv B) E₁ + E₂ = hv C) E₁ – E₂ = hv D) E₁/E₂ = h
What do h and ν represent in the equation E₁ – E₂ = hν? A) Heat and volume B) Height and velocity C) Planck’s constant and frequency of radiation D) Pressure and number of atoms
Limitations of Bohr’s atomic model
Which atomic spectra can’t be explained by Bohr’s theory? A) Helium only B) Multi-electron atoms C) Hydrogen D) Radioactive atoms
What is the Zeeman effect? A) Electron gets removed from atom B) Splitting of spectrum in electric field C) Spectrum lines split in magnetic field D) Spectrum lines merge
What does Bohr’s theory fail to explain about Zeeman effect? A) Frequency of radiation B) Energy gap C) Spectral line splitting in magnetic field D) Velocity of particle
What does modern research reveal about electron movement? A) Electrons don’t move B) Electrons spin in straight lines C) Electrons may move in elliptical orbits D) Electrons jump into the nucleus
C) Atom emits or absorbs energy
C) When an electron goes from higher to lower level
C) Electron jumping to higher level with energy absorption
B) The difference in energies before and after orbit change
C) E₁ – E₂ = hν
C) Planck’s constant and frequency of radiation
B) Multi-electron atoms
C) Spectrum lines split in magnetic field
C) Spectral line splitting in magnetic field
C) Electrons may move in elliptical orbits
Quantum number
Principal and Subsidiary quantum number
Meaning and types of quantum numbers
What do quantum numbers help describe about electrons? A) Size and taste of atom B) Temperature and density C) Position, energy, spin, size, and shape of energy levels D) Atomic mass and number
How many types of quantum numbers exist? A) Two B) Three C) Four D) Five
Which one is not a type of quantum number? A) Principal B) Subsidiary C) Rotational D) Spin
Principal quantum number (n)
What does the principal quantum number express? A) Temperature of atom B) Number of neutrons C) Orbits or principal energy levels of electrons D) Ionization potential
What is the symbol of the principal quantum number? A) l B) m C) s D) n
What is the value of n for the first orbit? A) 0 B) 2 C) 3 D) 1
Naming of electron shells
What are the energy levels also called? A) Electron clouds B) Electron shells C) Subshells D) Nodes
What is the name of the innermost shell? A) L shell B) M shell C) K shell D) Q shell
Which letters are used for the outer shells beyond K? A) A, B, C B) P, Q, R C) L, M, N, O, P, Q D) W, X, Y
Which energy level is closest to the nucleus? A) Fifth B) Second C) First D) Fourth
Subsidiary (Azimuthal) quantum number (l)
What is another name for the subsidiary quantum number? A) Magnetic quantum number B) Spin quantum number C) Azimuthal quantum number D) Radial quantum number
What does the subsidiary quantum number describe? A) Number of electrons in shell B) Shape of nucleus C) Sublevel of the electron D) Size of the atom
What symbol is used for subsidiary quantum number? A) m B) s C) n D) l
What determines the possible values of l? A) Proton number B) Atomic weight C) Value of n D) Atomic radius
Range and identification of sublevels (s, p, d, f)
For a given value of n, what values can l have? A) 1 to n B) n to n+1 C) 0 to n–1 D) –n to +n
C) Position, energy, spin, size, and shape of energy levels
C) Four
C) Rotational
C) Orbits or principal energy levels of electrons
D) n
D) 1
B) Electron shells
C) K shell
C) L, M, N, O, P, Q
C) First
C) Azimuthal quantum number
C) Sublevel of the electron
D) l
C) Value of n
C) 0 to n–1
Quantum number
3. Magnetic quantum number
What is the symbol for the magnetic quantum number? A) l B) s C) m D) n
What does the magnetic quantum number explain? A) Size of the orbit B) Shape of the orbital C) Orientation of the orbital in space D) Distance from the nucleus
If l = 1 (p orbital), what values can the magnetic quantum number have? A) –1, 0, +1 B) –2, –1, 0 C) 0, +1, +2 D) –1, +1, +2
How many types of p orbitals are there? A) Two B) Three C) Four D) Five
What are the three types of p orbitals called? A) Py, Pz, Pw B) Px, Py, Pz C) Px, Py, Pn D) P1, P2, P3
4. Spin quantum number
What does the spin quantum number represent? A) Shape of the orbit B) Direction of the electron spin C) Position of the nucleus D) Velocity of electron
What is the symbol for spin quantum number? A) n B) m C) l D) s
In how many directions can an electron spin? A) One B) Two C) Three D) Four
What are the possible values of the spin quantum number? A) +1, –1 B) +½, –½ C) 0, 1 D) +1, 0
How are the two electron spin directions shown? A) Circles B) Arrows in same direction C) Arrows in opposite directions D) Dashed lines
C) m
C) Orientation of the orbital in space
A) –1, 0, +1
B) Three
B) Px, Py, Pz
B) Direction of the electron spin
D) s
B) Two
B) +½, –½
C) Arrows in opposite directions
Quantum number
Aufbau’s law and Pauli’s Exclusion Principle
Aufbau’s Law
According to Aufbau’s law, electrons go to the different orbitals according to their: A) Decreasing energy B) Increasing energy C) Random order D) None of the above
The orbital with a lower value of (n + l) has: A) Higher energy B) Lower energy C) Same energy D) No electrons
What is the value of n for 4s orbital? A) 3 B) 2 C) 4 D) 1
What is the value of l for 3d orbital? A) 0 B) 1 C) 2 D) 3
Which orbital is filled first—4s or 3d? A) 4s B) 3d C) Both together D) Cannot be said
What is the value of (n + l) for the 4p orbital? A) 4 B) 5 C) 6 D) 3
If two orbitals have the same (n + l) value, the electron enters the one with: A) Higher n B) Lower n C) Same n D) Any n value
Pauli’s Exclusion Principle
Pauli’s principle states that no two electrons in the same atom can have: A) Same one quantum number B) Same two quantum numbers C) Same three quantum numbers D) Same four quantum numbers
According to Pauli’s principle, two electrons can occupy the same orbital if they have: A) Same spin B) Opposite spin C) Random spin D) No spin
✅ Answers:
B) Increasing energy
B) Lower energy
C) 4
C) 2
A) 4s
B) 5
B) Lower n
D) Same four quantum numbers
B) Opposite spin
