Unit 2 Chemistry

principal energy level

principal energy level

the shell or orbital in which the electron is located relative to the atom's nucleus

quantum

single packet of matter or energy

electromagnetic spectrum

the entire frequency range of electromagnetic waves

amplitude

how high the peak is or how low the trough is to the line that the wave is on

wavelength

distance between the center point of a peak to another peak (applicable to troughs)

frequency

the number of waves that pass a certain point in a specified amount of time

hertz (hz)

SI unit for frequency

atomic emission spectrum

spectrum that shows what light is absorbed and emitted

planck's equation

E=hv (Energy = planck's constant * frequency)

photoelectric effect

emission of electrons when electromagnetic radiation, such as light, hits a material

photon

light particle

ground state

the lowest energy state of electron

excited state

high energy state of an electron

quantum mechanical model

the accepted model of the atom. combines ideas of Rutherford's discovery of the nucleus, Planck's energy equation, and Einstein's idea that photons are particles that move like waves

Aufbau's rule

electrons fill subshells of the lowest available energy, then they fill subshells of higher energy

pauli exclusion principle

2 arrows in a box (orbital notation) cannot face the same direction

Hund's rule

Each orbital is occupied by one electron first before they are double occupied. (draw ↑ in each box for orbital notation before you add ↓)

atomic sublevels

s p d f. sublevels of energy levels

atomic orbitals

a function describing the location and wave-like behavior of an electron in an atom

uncertainty principle

principle that states it is impossible to figure out the exact location of small particles such as electrons

valence electron

electrons in the outer shell of an atom

electronegativity

the tendency of an atom to attract electrons in the formation of an ionic bond

ion

electrically charged atom

cation

a positively charged ion

anion

a negatively charged ion

What element did Bohr work with nearly exclusively and what phenomenon caused him to develop his own atomic model?

Hydrogen. The phenomenon is that hydrogen would produce different spectral lines. The reason behind this is that the electron of hydrogen could fall from the 6th shell to the 1st shell, but it could also fall from the 3rd shell to the 1st. This would produce different spectral lines. He proposed that electrons move around the nucleus in energy levels.

What improvements did Bohr make upon Rutherford’s atomic model?

He proposed that electrons orbit the nucleus in energy levels.

How can we use a periodic table to determine the number of principal energy levels an atom of a given element has?

Using the periods on the side of the periodic table

According to the Bohr model, how many electrons can each of the first three energy levels hold?

2, 8, 18

What sort of research did Planck conduct and how is it directly related to the Bohr model?

Planck researched black body radiation. He came up with the equation E=hv. This is directly related to Bohr's model because electrons orbit around the nucleus in energy levels. These electrons can emit energy in the form of photons.

What is a quantum?

the smallest discrete unit of a phenomenon

What does it mean to quantize something?

to divide a phenomenon into small, discrete packets.

Are all quanta equal? Explain.

No. For example, not all photons are the same. Photons can have different amounts of energy.

What do we call a quantum of electromagnetic radiation?

photon

Draw a transverse wave and label the parts.

What revolutionary concept did Einstein propose as an explanation for the photoelectric effect?

Proposed light is made of photons that move like waves. He said that the photons transfer their energy to the electrons and then they are ejected from the material.

What is an atomic emission spectrum and how did Bohr’s atomic model explain it?

The atomic emission spectrum shows what visible light is emitted and absorbed by an element. The Bohr model explains that when an electron falls from a high energy level, energy is released in the form of a photon. The energy released is represented by the spectral lines on the atomic emission spectrum.

Can we calculate the amount of energy a photon has? If so, how?

E=Hv

If the velocity of two waves is the same, how can we determine which wave has more energy?

By it's amplitude.

What affects the frequency of a photon more, speed or wavelength?

Wavelength

What about a hydrogen atom is Bohr’s model able to accurately predict? What are the limitations of the Bohr model?

The atomic light spectra of a hydrogen atom. The Bohr model is only applicable to hydrogen atoms.

What effect did de Broglie’s equation have on the atomic model? How did it change Bohr’s model?

De Brogile's equation explained electrons wave like properties.

How did Schrödinger use de Broglie’s wave equation and Heisenberg’s uncertainty principle to devise the quantum mechanical model of the atom?

In the Schrödinger model, the electrons behave as standing waves that have a greater probability of being in some regions of space (orbitals) than in others.

Where does the quantum mechanical model state that electrons may be found? How is this different from Bohr’s model?

In orbitals. Bohr's model stated that electrons are on fixed paths, whereas the quantum mechanical model incorporated Heisenberg's uncertainty principle, which states that it is impossible to find where an electron may be in an atom; however, it's possible to find where an electron is most likely located. The areas where electrons are likely to be are called orbitals.

What is a sublevel? How is it different from a principal energy level?

A sub-level makes up principle energy levels.

What is an orbital? What determines the shape of an orbital?

An orbital are areas where electrons are likely to be. The angular momentum quantum number

What determines the size of an orbital?

Principal quantum number

What are the four sublevels and what is the maximum number of associated orbitals for each one?

S P D F. 1 3 5 7 orbitals

What is the shape of an s orbital?

S orbitals are spheres. P orbitals are dumbbell shaped. D orbitals are clover leaf shaped except for one that is an elongated dumbbell with a donut shape in between. F orbital shape varies

At what point, in the quantum mechanical model do the energy states of the principal energy levels start to overlap?

At n=3

What is the rule for determining the principal energy level of a d sublevel? An f sublevel?

-1 and -2

Under what circumstances will the Aufbau principle be violated? Why is this?

When an electron from an orbital is moved to another orbital so that the orbital can be stable. To be stable, orbitals either have half full or full orbitals.

How is noble gas notation different from complete sublevel notation?

A noble gas will replace part of the complete sublevel notation.

What are valence electrons and what can they tell us about an atom?

Electrons on the outer shell. Can tell us how they bond with other elements.

How are the electron configurations of elements in the same family/group similar?

The electron configuration in the outer energy level of the atoms in a family is the same

How do ions form?

addition or removal of electrons

How does a representative element’s electron configuration change when it forms an ion?

The amount of electrons changes, so an atom may have the same amount of valence electrons as other elements.

How does a cation’s radius compare to the radius of a neutral atom of the same element? An anion?

Cat ion smaller. Anion bigger