BackIntroduction to Chemistry: Electrons in Atoms and the Periodic Table
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1/28BackSkip to main contentBackWhy was the Hindenburg airship filled with hydrogen gas?
Hydrogen gas was used for buoyancy because it is less dense than air, but it is highly reactive and flammable. What makes helium gas inert?
Helium has a highly stable electron configuration with two protons and two electrons, making it chemically inert. What does Mendeleev's periodic law state?
When elements are arranged by increasing atomic mass, certain sets of properties recur periodically. What is the speed of light (c)?
Light travels through space at a constant speed of 3.0 x 10\(8\) m/s. What is wavelength (λ) in light waves?
Wavelength is the distance between adjacent wave crests in a light wave. How many colors does white light split into when passed through a prism?
White light splits into 7 colors: red, orange, yellow, green, blue, indigo, and violet. Which visible light color has the longest wavelength and which has the shortest?
Red light has the longest wavelength (750 nm), and violet light has the shortest wavelength (400 nm). What is frequency (ν) in electromagnetic waves?
Frequency is the number of wave crests passing a point per second, inversely related to wavelength. What part of the electromagnetic spectrum has the highest energy?
Gamma rays have the highest energy in the electromagnetic spectrum. What is the difference between a white light spectrum and an emission spectrum?
White light spectrum is continuous, while emission spectra of elements contain discrete specific wavelengths. What is the key idea of Bohr's atomic model?
Electrons travel in fixed, circular orbits around the nucleus at specific quantized energy levels. What happens when an electron jumps from a higher to a lower energy orbit in Bohr's model?
A photon of light is emitted corresponding to the energy difference between the orbits. Why was the Bohr model replaced by the quantum-mechanical model?
Bohr's model failed to explain emission spectra of multi-electron elements and lacked a full description of electron behavior. What do quantum-mechanical orbitals represent?
Orbitals represent probability maps showing where an electron is likely to be found, not exact paths. What does the principal quantum number (n) describe?
The size and energy level of an orbital; higher n means larger size and higher energy. What shapes correspond to angular quantum numbers (l) 0, 1, and 2?
l=0: spherical (s), l=1: dumbbell (p), l=2: cloverleaf (d) shapes. What does the magnetic quantum number (m) describe?
The orientation of an orbital in space; m ranges from -l to +l. What is the Pauli exclusion principle?
An orbital can hold a maximum of two electrons with opposite spins. What is Hund's rule?
Electrons occupy orbitals of the same energy singly first, with parallel spins, before pairing. How many valence electrons does sulfur have if its configuration is 1s2 2s2 2p6 3s2 3p4?
Sulfur has 6 valence electrons and 10 core electrons. What general electron configuration do alkali metals (Group 1A) have?
ns1; they lose one valence electron to form +1 cations. What general electron configuration do halogens (Group 7A) have?
ns2 np5; they gain one electron to form -1 anions. What is the maximum number of electrons in a d orbital?
A d orbital can hold up to 10 electrons. How many p orbitals are in the second shell?
There are 3 p orbitals in the second shell. How many d orbitals are in the third shell?
There are 5 d orbitals in the third shell. Which orbital fills first among 3p, 4s, and 3d?
The 4s orbital fills before 3d and 3p orbitals. What is the electron configuration notation for chlorine using noble gas core notation?
[Ne] 3s2 3p5 What determines the chemical properties of elements?
The number of valence electrons largely determines chemical properties.
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