atomic structure

Question 2

What is atomic number? The number of protons in an atom

Answer 2

represented by Z.

Question 3

What are isotopes?

Answer 3

Atoms of the same element with different numbers of neutrons.

Question 4

What are isobars?

Answer 4

Atoms of different elements with the same mass number but different atomic numbers.

Question 5

What are the fundamental particles of an atom?

Answer 5

neutrons & Protons

Question 6

What was Rutherford’s gold foil experiment?

Answer 6

An experiment where alpha particles were directed at a thin gold foil to study atomic structure.

Question 7

What were the conclusions of Rutherford’s experiment?

Answer 7

The atom has a dense positively charged nucleus

Question 8

What is electromagnetic radiation?

Answer 8

A form of energy that travels in waves including light

Question 9

What are the characteristic parameters of electromagnetic radiation?

Answer 9

Wavelength frequency

Question 10

What is the relationship between wavelength and frequency?

Answer 10

Wavelength (λ) and frequency (ν) are inversely proportional: c = λν.

Question 11

What is the hydrogen line spectrum?

Answer 11

A set of distinct lines observed in hydrogen’s emission spectrum.

Question 12

What are Bohr’s postulates?

Answer 12

1. Electrons orbit in fixed energy levels.
2. Energy is absorbed/emitted when electrons move between levels.
3. Angular momentum is quantized.

Question 13

What is the energy level diagram of hydrogen?

Answer 13

A diagram showing electron transitions between energy levels forming spectral series like Lyman

Question 14

Why are half-filled and fully filled orbitals stable?

Answer 14

Due to symmetrical distribution and exchange energy stabilization.

Question 15

What is wave-particle duality?

Answer 15

The concept that matter and radiation exhibit both wave-like and particle-like properties.

Question 16

What is Heisenberg’s uncertainty principle?

Answer 16

It is impossible to simultaneously determine the exact position and momentum of an electron.

Question 17

Why is the quantum mechanical model needed?

Answer 17

It explains electron behavior using wave functions and probability distributions.

Question 18

What are probability pictures of an electron?

Answer 18

Visual representations of electron cloud density showing where an electron is likely to be found.

Question 19

What are quantum numbers?

Answer 19

Numbers that describe an electron’s energy shape

Question 20

What is the significance of the principal quantum number (n)?

Answer 20

Indicates the energy level and size of the electron orbital.

Question 21

What does the azimuthal quantum number (l) represent?

Answer 21

Defines the shape of the orbital (spfd)

Question 22

What is the magnetic quantum number (mₗ)?

Answer 22

Determines the orientation of an orbital in space.

Question 23

What does the spin quantum number (mₛ) indicate?

Answer 23

Specifies the spin of the electron (+½ or -½).

Question 24

What are the shapes of s p d orbitals

Answer 24

s - spherical, p - dumbbell-shaped, d - complex clover-like.

Question 25

What is a nodal plane?

Answer 25

A region in an orbital where the probability of finding an electron is zero.

Question 26

What is Pauli’s exclusion principle?

Answer 26

No two electrons in an atom can have the same set of four quantum numbers.

Question 27

What is the Aufbau principle?

Answer 27

Electrons fill orbitals starting from the lowest energy level.

Question 28

What is Hund’s rule of maximum multiplicity?

Answer 28

Electrons fill degenerate orbitals singly before pairing up.

Question 29

Why are half-filled and fully filled orbitals more stable?

Answer 29

They provide lower energy configurations due to exchange energy and symmetry.

Question 30

How is atomic number related to chemical properties?

Answer 30

Elements with the same atomic number have the same number of protons and similar chemical properties.

Question 31

What is the difference between isotopes and isobars?

Answer 31

Isotopes have the same atomic number but different mass numbers while isobars have the same mass number but different atomic numbers.

Question 32

What did Rutherford's experiment disprove?

Answer 32

It disproved the plum pudding model showing that atoms have a dense nucleus.

Question 33

What was the major flaw in Rutherford’s model?

Answer 33

It could not explain why electrons do not spiral into the nucleus.

Question 34

What is the speed of electromagnetic radiation in a vacuum?

Answer 34

3.0 × 10⁸ m/s.

Question 35

What is Planck’s equation?

Answer 35

E = hν where E is energy

Question 36

What is the relation between energy and wavelength?

Answer 36

Energy is inversely proportional to wavelength: E = hc/λ.

Question 37

What is the Rydberg formula for hydrogen spectra?

Answer 37

1/λ = R_H (1/n₁² - 1/n₂²) where R_H is the Rydberg constant.

Question 38

What are the spectral series of hydrogen?

Answer 38

Lyman (UV) Balmer (visible)

Question 39

Why does the hydrogen spectrum have discrete lines?

Answer 39

Energy levels are quantized so electrons absorb/emit photons of specific energies.

Question 40

What are the limitations of Bohr’s model?

Answer 40

It only works well for hydrogen and does not explain multi-electron atoms.

Question 41

How does the quantum mechanical model improve upon Bohr’s model?

Answer 41

It describes electron behavior as probability distributions rather than fixed orbits.

Question 42

What is Schrödinger’s wave equation?

Answer 42

A mathematical equation describing the probability distribution of electrons in an atom.

Question 43

What is an atomic orbital

Answer 43

? A region in space where an electron is most likely to be found.

Question 44

How does probability relate to electron position in an atom?

Answer 44

The probability of finding an electron is given by the square of the wave function (ψ²).

Question 45

What are the shapes of f orbitals?

Answer 45

f orbitals have complex shapes often resembling multi-lobed structures.

Question 46

What is the total number of orbitals in a shell?

Answer 46

Determined by n² where n is the principal quantum number.

Question 47

What is the number of electrons that can be held in a shell?

Answer 47

Given by 2n² where n is the principal quantum number.

Question 48

What is an angular node?

Answer 48

A region where electron probability is zero due to orbital shape.

Question 49

What is a radial node?

Answer 49

A spherical region around the nucleus where electron probability is zero.

Question 50

How is the number of nodal planes in p orbitals determined?

Answer 50

p orbitals have one nodal plane.

Question 51

How does Pauli’s exclusion principle influence electron configuration?

Answer 51

It ensures no two electrons in an atom have identical quantum numbers.

Question 52

What is the order of filling of orbitals according to Aufbau principle?

Answer 52

Orbitals fill in increasing order of energy: 1s < 2s < 2p < 3s < 3p < 4s < 3d < 4p etc.

Question 53

What is the significance of Hund’s rule?

Answer 53

It maximizes electron stability by keeping unpaired electrons in degenerate orbitals with parallel spins.

Question 54

Why does Cr and Cu have unusual electron configurations? Due to extra stability of half-filled (Cr: 4s¹3d⁵) and fully filled (Cu: 4s¹3d¹⁰) d orbitals.

Question 55

How does exchange energy contribute to orbital stability? Exchange energy stabilizes half-filled and fully filled orbitals by increasing parallel spin interactions.