Chemistry: Unit 3 - Electrons and Their Arrangement Study Guide
Give the electron configuration for a neutral atom of beryllium. Draw its orbital diagram.
1s2 2s2
Give the electron configuration for a neutral atom of chlorine. Draw its orbital diagram.
1s2 2s2 2p6 3s2 3p5
Give the electron configuration for a neutral atom of selenium. Draw its orbital diagram.
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p4
Write the electron configuration for manganese. Both longhand and shorthand.
1s2 2s2 2p6 3s2 3p6 4s2 3d5 [Ar] 4s2 3d5
Speed of Light
3.00 x 10^8 m/s.
F-orbitals
A complex shaped orbital that has 7 different directions in 3d space. This orbital can contain up to 14 electrons.
Orbital Notation
A diagramic representation that uses dashes and arrows to show the principal energy levels and sublevels for all the electrons in an atom.
P-orbitals
A dumbell (propeller) shaped orbital that has 3 different directions in 3d space. This orbital can contain up to 6 electrons.
What does wavelength mean in terms of energy of the light?
A higher wavelength will decrease the amount of energy, while a lower wavelength will increase the amount of energy.
D-orbitals
A pear shaped orbital that has 5 different directions in 3d space. This orbital can contain up to 10 electrons.
Shell
A region of space around a nucleus that can be occupied by electrons, corresponding to a principal quantum number.
Orbital
A region of space in an atom where there is a high probability of finding electrons (90%).
Pauli Exclusion Principle
A rule that states an atomic orbital may describe at most two electrons, each with opposite spin direction.
Hund's Rule
A rule that states orbitals of equal energy are each occupied by one electron before any orbital is occupied by a second electron, and all electrons in singly occupied orbitals must have the same spin
Aufbau Principle
A rule that states that an electron occupies the lowest-energy orbital that can receive it before moving on to higher-energy orbitals.
Niels Bohr
A scientist who discovered that electrons orbit around the atom in specific electron shells and developed the planetary model of the atom, where electrons have shells and a higher shell means a higher energy level.
J.J. Thomson
A scientist who discovered the electron and proposed the plum pudding model, a model in which electrons float in a positively-charged goo.
Ernest Rutherford
A scientist who discovered the nucleus of the atom and also made the planetary model of the atom, where a positively charged and dense nucleus is located in the center of an atom and the electrons are floating outside of the nucleus.
Noble gas electron configuration
A shortened code which identifies the location of each electron in an element.
S-orbitals
A spherical shaped orbital that has no direction in 3d space. This orbital can contain up to 2 electrons.
Subshell
A subdivision of an energy level in an atom. They are divided into orbitals and are labeled s, p, d, and f in an electron configuration.
Valence Electron
An electron that is found in the outermost shell of an atom and that determines the atom's chemical properties.
Principle Quantum Number
Assigned by the quantum mechanical model to indicate the relative sizes and energies of atomic orbitals (the energy level occupied by the electron).
Write the electron configuration (both longhand and noble gas configurations) for an ion of barium.
Ba 2+ longhand: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 Ba 2+ shorthand: [Kr] 5s2 4d10 5p6
What do electrons release when they lose energy and drop to a lower energy level?
Electrons release visible light when they lose energy and drop to a lower energy level.
Isaac Newton
English mathematician who defined the laws of motion and gravity and tried to explain the motion of the universe.
Heisenberg/Schrodinger
Heisenberg and Schrodinger created the Quantum Mechanical model of the atom, which explained that electrons have a 90% chance of being found inside specific orbitals.
Wavelength
Horizontal distance between the crests, between the troughs, or between two corresponding parts of two adjacent waves.
How many valence electrons does an atom of iron have?
Iron has 2 valence electrons.
What is the electron configuration of potassium? (both longhand and noble gas)
K (19) 1s2 2s2 2p6 3s2 3p6 4s1 [Ar] 4s1
Write the electron configuration (both longhand and noble gas configurations) for an ion of nitrogen.
N 3- longhand: 1s2 2s2 2p6 N 3- shorthand: [He] 2s2 2p6
How many valence electrons does an atom of phosphorus have?
Phosphorus has 5 valence electrons.
How many valence electrons does an atom of rubidium have?
Rubidium has 1 valence electron.
Louis de Brogile
Suggest that if light can have both wavelike and particle like characteristics (Planck), then particles can also have wavelike characteristics. Suggested electrons could be both particles and waves, applying Einstein's particle-wave theory to electrons.
Quantum
The amount of energy needed to move an electron from one energy level to another.
Electron configuration
The arrangement of electrons of an atom in its ground state into various orbitals around the nuclei of atoms.
What is the order of the electromagnetic spectrum? Label the one with the longest wavelength and the shortest wavelength.
The electromagnetic spectrum is radio, microwave, infrared, visible, uv, x-ray, gamma ray. Radio waves have the longest wavelength. Gamma waves have the shortest wavelength.
If three electrons are available to fill three empty 2p atomic orbitals, how will the electrons be distributed in the three orbitals? Draw the orbital diagram for this.
The electrons will be evenly distributed in the three orbitals.
How does the energy of an electron change when the electron moves closer to the nucleus?
The energy level decreases and the electron gives off energy when the electron moves closer to the nucleus.
What are the exceptions to electron configurations? WHY? Give an example on how to actually write it.
The exceptions to the electron configuration is chromium and copper. This is due to the electrons being more stable at a lower level orbital than a higher level orbital because the lower level orbital is almost full or half full. Example for copper: [Ar] 4s1 3d10 Example for chromium: [Ar] 4s1 3d5
Amplitude
The height of a wave's crest.
Uncertainty Principle
The idea by Heisenberg that the behavior of subatomic particles is uncertain, suggesting that all of the physical laws governing the universe are based on uncertainty and we can only know they momentum or position of a particle.
What is the maximum number of d orbitals in a principal energy level (how many different types of d orbitals are there)?
The maximum number of d orbitals in a principal energy level is 5 (there are 5 different types of d orbitals).
What is the maximum number of electrons in the second energy level? Why?
The maximum number of electrons in the second energy level is 8. This is because 2s2 and 2p6 are the only orbitals available, which add up to 8 electrons.
Frequency
The number of complete wavelengths that pass a certain point in a given time.
The principal quantum number indicates what property of an electron? Example 2s^2 2= ____________________ Also, what does the s and the superscript 2 indicate? s= _____________________ 2= _____________________
The principal quantum number indicates the principal energy level of an electron. 2 is the principal quantum number. S is the shape of the orbital (suborbital). The subscript 2 represents the number of electrons in the orbital.
Light
The range of electromagnetic radiation that can be detected by the human eye.
Electromagnetic Spectrum
The range of wavelengths or frequencies over which electromagnetic radiation extends.
Energy Level
The specific amount of energy an electron has that corresponds to the orbital an electron can be found in.
Hertz
The unit of frequency, equal to one cycle per second.
How many energy sublevels are there in the second principal energy level? What are they?
There are 2 sublevels: 2s and 2p in the second principal energy level.
Which color of visible light has the shortest wavelength and highest energy?
Violet has the shortest wavelength and the highest energy within the visible light spectrum.
Emission of light from an atom occurs when the electron _____. a. Drops from a higher to a lower energy level b. Moves within its atomic orbital c. Jumps from a lower to a higher energy level d. Falls into the nucleus
a. Drops from a higher to a lower energy level
What type of atomic orbitals are in the third principal energy level? a. s, p, and d only b. s and p only c. p, d, and f only d. s, p, d, and f e. p and d only
a. s, p, and d only
The shape (not the size) of an electron cloud is determined by the electron's ___? a. Speed b. Energy sublevel c. Position d. Principal quantum number e. Spin
b. Energy sublevel
The letter "p" in the symbol 4p^3 indicates the ___. a. Speed of an electron b. Orbital shape c. Spin of an electron d. Principal energy level
b. Orbital shape
What is the wavelength of light with a frequency of 1.0 x 10^20 hz?
c = f * w c/f = w 3.0 x 10^8 m/s / 1.0 x 10^20 hz = 3.0 x 10^-12 m
What is the frequency of light with wavelength 1.0 x 10^-8 m?
c = f * w c/w = f 3.0x10^8 m/s / 1.0 x 10^-8 m = 3x10^16 1/s
What is the probability of finding an electron within the region indicated by the drawn electron cloud? a. 67% b. 50% c. 90% d. 100% e. 75%
c. 90%
When an electron moves from a lower to a higher energy level, the electron ___? a. Absorbs a continuously variable amount of energy b. Always doubles its energy c. Moves closer to the nucleus d. Absorbs a quantum of energy
d. Absorbs a quantum of energy.
In order to occupy the same orbital, two electrons must have ___. a. Low energy b. A high quantum number c. The same direction of spin d. Opposite direction of spin
d. Opposite direction of spin
The lowest energy state of an atom is called the _______. a. Dependent state b. Configuration state c. Excited state d. Independent state e. Ground state
e. Ground state
The quantum mechanical model exactly predicts which characteristic of electrons in an atom? a. Energy b. Position c. Charge d. Orbit e. None of the above
e. None of the above
