Atomic models, Electron configuration, and Spectra

What did Democritus propose about matter?

He proposed that matter is composed of tiny, indivisible particles called 'atomos'.

What are the four classical elements according to early theories?

Fire, air, water, and earth.

What did Dalton state about atoms in 1804?

All elements are composed of tiny particles called atoms, which are identical for the same element and different for different elements.

What is the significance of compounds in atomic theory?

Atoms of different elements can physically mix or chemically combine to form compounds.

What does the Bohr model describe about electron paths?

Electrons travel in defined paths or orbits around the nucleus, known as shells or principal energy levels.

What is the Wave-Mechanical Model of the atom?

It describes orbitals as areas of highest probability where an electron is likely to be found, with cloud-like shapes.

What did Thomson discover in 1897?

He discovered negatively charged particles, now known as electrons, using a cathode ray tube.

What was the conclusion of Rutherford's Gold Foil Experiment?

He discovered the nucleus, a small, dense, positively charged core of the atom.

What is the charge and mass of a proton?

A proton has a charge of +1 and a mass of approximately 1 atomic mass unit (amu).

What is the charge and mass of an electron?

An electron has a charge of -1 and a negligible mass (1/1836 amu).

What is the atomic number?

The atomic number is the number of protons in an atom, which identifies the element.

What is the mass number?

The mass number is the sum of protons and neutrons in an atom.

What is an isotope?

Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons.

What is Avogadro's number?

Avogadro's number is 6.02214 x 10^23, representing the number of atoms in one mole of a substance.

How is the average atomic mass calculated?

It is calculated as a weighted average of the atomic masses of its isotopes based on their relative abundances.

What does the term 'mass spectrum' refer to?

A mass spectrum shows the distribution of isotopes of an element based on their mass and relative abundance.

What is the significance of the Oil Drop Experiment conducted by Millikan?

It determined the charge of an electron to be approximately 1.602 x 10^-19 coulombs.

What does the term 'quantum mechanical model' refer to?

It refers to the Wave-Mechanical Model that describes the behavior of electrons in atoms using probabilities.

What is the relationship between atomic mass and atomic number?

Atomic mass is the total number of protons and neutrons, while atomic number is solely the number of protons.

What is the isotopic symbol for Carbon-14?

The isotopic symbol is 14C, where 14 is the mass number and 6 is the atomic number.

How do isotopes differ in terms of neutrons?

Isotopes have the same number of protons but different numbers of neutrons.

What is the significance of the atomic mass unit (amu)?

1 amu is defined as 1/12th the mass of a carbon-12 atom.

What is the Aufbau principle?

Electrons enter orbitals of lowest energy first.

What does the Pauli Exclusion Principle state?

No more than two electrons can occupy an orbital, and they must have opposite spins.

What is Hund's Rule?

When electrons enter orbitals of equal energy, they will maximize spin in the same direction.

What is the ground state of an atom?

When all electrons occupy the lowest available orbitals.

What is the excited state of an atom?

When electrons have absorbed energy and occupy higher energy levels.

How many sublevels are in the second principal energy level (PEL)?

2 sublevels (s and p).

What is the maximum number of electrons in the third principal energy level?

18 electrons (2 in s, 6 in p, and 10 in d).

What is the significance of the bright line emission spectrum?

It represents discrete wavelengths emitted during electron transitions between energy levels.

What is the formula for calculating energy of a photon?

E = hv, where E is energy, h is Planck's constant, and v is frequency.

What does the term 'valence electrons' refer to?

Electrons in the outermost principal energy level.

What is the maximum number of orbitals in the fourth principal energy level?

16 orbitals.

What does the term 'quantum' refer to in electron transitions?

A specific amount of energy required for an electron to move to a higher energy level.

How does the wavelength relate to frequency in electromagnetic radiation?

The speed of light (c) equals the product of wavelength (λ) and frequency (ν): c = λν.

What is the relationship between energy and wavelength?

Energy is inversely proportional to wavelength; shorter wavelengths have higher energy.

What is a condensed electron configuration?

An abbreviated way to represent electron configurations using noble gas notation.

What is the electron configuration for Sodium (Na)?

[Ne] 3s¹

What is the electron configuration for Magnesium (Mg)?

1s² 2s² 2p⁶ 3s²

What is the electron configuration for Carbon (C)?

1s² 2s² 2p²

What is the electron configuration for Oxygen (O)?

1s² 2s² 2p⁴

What is the electron configuration for Fluorine (F)?

1s² 2s² 2p⁵

What is the electron configuration for Neon (Ne)?

1s² 2s² 2p⁶

What is the electron configuration for Iron (Fe)?

[Ar] 4s² 3d⁶

What is the electron configuration for Chromium (Cr)?

[Ar] 4s¹ 3d⁵ (half-filled orbitals are more stable).

What is the electron configuration for Copper (Cu)?

[Ar] 4s¹ 3d¹⁰ (filled orbitals are more stable).