Atomic Structure
Which subatomic particle determines the identity of an element?
Protons
Who first proposed the idea of the atom?
Democritus
What happens to an electron when it absorbs energy?
It moves to a higher energy level / excited state.
How many orbitals are found in each sublevel: s, p, d, and f?
s = 1, p = 3, d = 5, f = 7
What equation relates wavelength and frequency?
c = λf
An atom contains 19 protons, 20 neutrons, and 19 electrons. What is its mass number?
39
Which scientist discovered the electron?
J.J. Thomson
What happens when an excited electron returns to a lower energy level?
Energy is emitted/released as a photon.
Identify the element represented by:
1s² 2s² 2p⁶ 3s² 3p³
Phosphorus (15 electrons)
What equation relates the energy of a photon to its frequency?
E = hf
A particle contains 16 protons and 18 electrons. What is its charge?
2-
Which scientist performed the gold foil experiment?
Ernest Rutherford
What are the four main parts/features of a wave that you should be able to identify on a diagram?
Crest, trough, wavelength, and amplitude
Write the full electron configuration for an atom containing 18 electrons.
1s² 2s² 2p⁶ 3s² 3p⁶
A wave has a wavelength of:
5.00 × 10⁻⁷ m
Calculate its frequency.
Use c = 3.00 × 10⁸ m/s
f = c/λ
f = (3.00 × 10⁸)/(5.00 × 10⁻⁷)
f = 6.00 × 10¹⁴ Hz
Atom A has 8 protons and 8 neutrons. Atom B has 8 protons and 10 neutrons. What is the relationship between these atoms?
They are isotopes of the same element.
Which scientist proposed that electrons occupy specific energy levels around the nucleus?
Niels Bohr
If the wavelength of electromagnetic radiation decreases, what happens to its frequency?
Frequency increases. They have an inverse relationship.
An atom has four electrons in its 2p sublevel. A student draws:
[↑↓] [↑↓] [ ]
Which rule is violated, and what should the correct arrangement be?
Hund’s Rule
An element has two naturally occurring isotopes:
Isotope A:
Mass = 62.0 amu
Abundance = 40.0%
Isotope B:
Mass = 65.0 amu
Abundance = 60.0%
Calculate the average atomic mass.
(62.0)(0.400) + (65.0)(0.600)
24.8 + 39.0 =
63.8 amu
A particle has a mass number of 31, 16 neutrons, and a 3− charge. Determine its number of protons AND electrons.
31 − 16 = 15 protons
3− means it gained 3 electrons → 18 electrons
Rutherford's gold foil experiment showed that most alpha particles passed straight through the foil, but a few were strongly deflected. What two conclusions about atomic structure did this evidence support?
The atom is mostly empty space AND contains a small, dense, positively charged nucleus.
Photon A has a higher frequency than Photon B.
Without calculating, compare their:
Photon A has a shorter wavelength and greater energy.
An atom contains 13 electrons.
Aluminum
1s² 2s² 2p⁶ 3s² 3p¹
3p: [↑] [ ] [ ]
A photon has a frequency of:
4.00 × 10¹⁴ Hz
Calculate:
a. Its wavelength
b. Its energy
Use:
c = 3.00 × 10⁸ m/s
h = 6.626 × 10⁻³⁴ J·s
λ = c/f
λ = (3.00 × 10⁸)/(4.00 × 10¹⁴)
λ = 7.50 × 10⁻⁷ m
Then:
E = hf
E = (6.626 × 10⁻³⁴)(4.00 × 10¹⁴)
E = 2.65 × 10⁻¹⁹ J