Atomic Theory Chem Test (DH)
D sublevels
- 4/5 are x shaped - 5 orbitals/sublevel
F sublevels
- 7 orbitals/sublevel
P sublevels
- dumbbell shape - 3 orbitals/sublevel - perpendicular on the x, y and z axes
S sublevels
- spherical shaped orbitals - only 1 orbital/sublevel
How many electrons would you need to weigh on the same balance to measure the same mass as that of a single proton?
1840 electrons to reach the mass of 1 proton.
Order of chart.
1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p
What is the speed of light constant
3.00 x 10^8 m/s - velocity
What are atomic orbitals?
3D shapes around the nucleus, where electrons are found.
What do the superscript and the subscript in the notation 40/19 K represent?
40 = mass number, 19 = atomic number
How many protons and electrons are contained in an atom of element 44?
44 protons, 44 electrons
Plank's constant
6.626 x 10^-34 j x s - end with joules as unit - h
Wavelength equation
???
Explain the direction of a cathode ray inside a cathode-ray tube.
A cathode ray is composed of a stream of electrons that originate from the cathode and flow through the tube to the anode
What does quantum mean?
A quantum is the minimum amount of energy that can be lost or gained by an atom.
Explain why a single atom of hydrogen cannot produce all four hydrogen spectral lines simultaneously
A single hydrogen atom only has one electron so it can not be able to produce all four hydrogen spectral lines simultaneously.
Explain Plank's quantum concept as it relates to energy lost or gained by matter.
According to Planck, for a given frequency, n, matter can emit or absorb energy only in discrete quanta that are whole-number multiples of hn, where h is Planck's constant.
Why is it impossible to know precisely the velocity and position of an electron at the same time?
According to the Heisenberg Principle, it states that we are not able to know precisely the velocity and position of an electron at the same time because (1) we do not have the detection equipment for it and (2) both the position of the electron and its velocity require the same amount of photons, therefore they need to be solved separately.
How did Bohr explain atomic emission spectra?
Bohr proposed that atoms emit light of certain wavelengths, and energies, when electrons move from higher-energy orbits to lower-energy orbits.
Compare and contrast Bohr's model and the quantum mechanical model of an atom.
Bohr's model shows the jump of an electron between sublevels, and according to that, it shows how much energy is given off. However, in the quantum mechanical model of an atom, it shows what area an electron can be found in (but not its precise location).
Speed of Light Equation
C = Lamba * Frequency C = (NM) * (HRTZ [per second]/second)
What experimental results led to the conclusion that electrons were part of all forms of matter?
Changing the type of electrode or type of gas did not affect the ray produced
What are the general properties of metalloids?
Have a mix of properties from both metals and non metals. Typical metalloids have a metallic appearance, but they are brittle and only fair conductors of electricity. Chemically, they behave mostly as nonmetals.
How can we see all four colors from a hydrogen gas discharge tube simultaneously?
In a hydrogen gas discharge tube, there are millions of hydrogen atoms filling the tube. Each one can have a different transition occurring, so all of the colors are represented by some fraction of the atoms present.
What was Henry Moseley's contribution to the modern understanding of the atom?
Henry Mosley discovered the atomic number by using an electron gun and found out that elements give off x-rays, which is how he was able to measure the atomic number. He found the atomic number of elements by using an electron gun and found out that elements give off x rays
According to the Bohr Model, how do electrons move in atoms?
Neil Bohr said that the electron must orbit around the nucleus in fixed energy levels . The energy must be given out when "excited" electrons fall from a high energy level to a low energy level.
How is the mass number related to the number of protons and neutrons an atom has?
Number of protons + number of neutrons = mass number
How is an atom's atomic number related to its number of protons? To its number of electrons?
Number of protons = atomic number In an atom, the number of protons and electrons will always be the same, unless chemically changed.
Differentiate between the wavelength of visible light and the wavelength of a moving soccer ball.
The difference is that wavelengths of visible light are electromagnetic, whereas the wavelength of a moving soccer ball is mechanical.
Explain why one electron in a rubidium atom occupies a 5s orbital rather than a 4d or 4f orbital?
The orbital related to the 5s sublevel has a lower energy than orbitals related to the 4d and 4f sublevels. (think of chart in powerpoint)
How does the quantum mechanical model of the atom describe the paths of an atom's electrons?
The quantum mechanical makes no description of the electrons' paths.
Which color has the highest energy? The lowest energy?
Violets have the highest energy and reds have the lowest energy.
What does wavelength mean?
Wavelength is the shortest distance between equivalent points on a continuous wave. - lambda - m or nm
Arrange ultraviolet light, radio waves, microwaves, and x-rays in order of increasing wavelength.
X-rays, ultraviolet light, microwaves, radio waves
Do all colors of light travel at the same speed?
Yes.
Frequency equation
c = lamda(v)
What does n represent in the quantum mechanical model of an atom?
n represents the energy level and relative size of the electron's orbital
How many orientations are possible for the orbitals related to the s, p, d, and f sublevels?
s-1 p-3 d-5 f-7
Which subatomic particle was discovered by researchers working with cathode ray tubes?
Electron.
An isotope of mercury has 80 protons and 120 neutrons. What is the mass number of this isotope?
Mass number = 200
State the main points of Dalton's atomic theory using your own words. Which parts of Dalton's theory were later found to be erroneous? Explain why.
1. Atoms are tiny, hard balls 2. Each chemical element had its own atoms that differed from others in mass 3. Believed that atoms were the fundamental building blocks of nature and that they could not be split* 4. In chemical reactions, atoms can rearrange and combine with other atoms *Atoms can be split into smaller particles because we can chemically break it down to electrons, protons, and neutrons
Describe the structure of a typical atom. Identify where each subatomic particle is located.
An atom has a nucleus in the center where protons and neutrons are located. Electrons orbit around the nucleus and are located in the electron cloud or empty space.
Define an atom. **
An atom is the unit for a chemical element and is the smallest building block of matter. It contains protons, neutrons, and electrons.
What does ground state mean?
An atom's ground state is its lowest allowable energy state.
What is the difference between an atom's ground state and an excited state?
An atom's ground state is its lowest energy state, while any energy state higher than the ground state is an excited state.
Explain how Mendeleev's periodic table was in error.
Arranging the elements by mass resulted in several elements being placed in groups of elements with different properties
Explain why atomic radii decrease as you move from left to right across a period.
As you move across a period, the atomic radius decreases, that is, the atom is smaller. The outer electrons are closer to the nucleus and more strongly attracted to the center because the protons are more compact. Therefore, it becomes more difficult to remove the outermost electron.
Why are electron's wavelengths easy to detect?
Because electrons are tiny, small particles that have a small mass.
Who originally proposed the concept that matter is composed of tiny, indivisible particles?
Democritus, John Dalton
Energy Equation (plancks equation)
E (energy) = H(Plancks constant) * V (Frequency) Plancks constant is 6.626 * 10^-34 E = Joules per second
Energy equation
E = hv
What makes up most of the volume of an atom? What makes up most of the mass of an atom?
Electron cloud. The nucleus.
How many energy sublevels are contained in each of the hydrogen atom's first three energy levels?
Energy level 1 has one sublevel; energy level 2 has two sublevels; energy level 3 has three sublevels
Evaluate the experiments that led to the conclusion that electrons are negatively charged particles found in all matter.
Firstly, Thomson discovered the electron. He used a Cathode Ray Tube and discovered that the beam of particles were attracted to a positive charge, meaning that the particles had a negative charge. Additionally, Rutherford's Gold Foil Experiment was that he used alpha particles that he thought would pass through the gold foil, but instead bounced off at different angles. From this, he concluded that the nucleus was concentrated with a positive charge and that electrons orbited around the the nucleus.
What does frequency mean?
Frequency is the number of waves that pass a given point per second. - v - hertz
What group are alkali metals from?
Group 1
What group are halogens from?
Group 17
What group are noble gases from?
Group 18
What group are alkali earth metals from?
Group 2
Describe the general characteristics of metals.
Shiny, bendable, conductors of heat and electricity, malleable, ductile, (left of the stair step line)
How does the quantum mechanical model of an atom describe the paths of an atom's orbitals?
It does not.
Whose work is credited with being the beginning of modern atomic theory?
John Dalton Founded the Billard Ball Model
Summarize Dalton's atomic theory.
John Dalton's atomic theory was that atoms are like tiny, hard balls that are indestructible, which is not true because atoms can be broken down into smaller particles.
Describe the relative orientations of the orbitals related to an atom's 2p sublevel.
Lying along the x, y, and z coordinate axes, the three p orbitals are mutually perpendicular.
An isotope of Xenon has an atomic number of 54 and contains 77 neutrons. What is the xenon isotope's mass number?
Mass number = 131
Compare the relative charge and mass of each of the subatomic particles.
Proton: (+), 1 Neutron: (no charge, 0), 1 Electron: (-), 1/1840
Which particles account for most of an atom's mass?
Protons and neutrons account for most of an atom's mass. These subatomic particles are found in the nucleus of the atom, where they form nucleons.
What particles are found in the nucleus of an atom? What is the charge of the nucleus?
Protons and neutrons; the charge of the nucleus is positive
Briefly explain how Rutherford discovered the nucleus.
Rutherford aimed a beam of alpha particles at a thin foil of gold. He expected most of the alpha particles to pass through the gold atoms, confirming the plum pudding model. However, a few particles were deflected at very large angles, which led to the discovery of the positively charged nucleus.
What is the name of the atomic model in which electrons are treated as waves? Who first wrote the electron wave equations that led to this model.
The Quantum Mechanical Model of an Atom. Erwin Schrödinger.
How was an electric field used to determine the charge of a cathode ray?
The alpha particles were deflected by the positively charged gold nuclei.
Particle Deflection: What caused the deflection of the alpha particles in Rutherford's gold foil experiment?
The alpha particles were deflected by the positively charged gold nuclei.
Explain what keeps the electrons confined in the space surrounding the nucleus.
The electrons are held within the atom by their attraction to the positively charged nucleus.
What is the relationship between wavelength and energy of light?
The higher the energy, the shorter the wavelength, and the lower the energy, the longer the wavelength.
What is ionization energy?
The ionization energy is defined as the amount of energy required to remove the most loosely bound electron, the valence electron, of an isolated gaseous atom to form a cation.
What do the sublevel designations s, p, d, and f specify with respect to the atom's orbitals?
Their shapes
Why are you unaware of the wavelengths of moving objects such as automobiles and tennis balls?
Their wavelengths are too small to be seen.
How do isotopes of a given element differ? How are they similar?
They differ in their amount of neutrons. They are similar in their amount of protons (and electrons).
Light is said to have a dual wave-particle nature. What does this mean?
This means that light's behavior becomes wave-like in some cases and particle-like in other cases.
Compare and contrast Thomson's plum pudding atomic model with Rutherford's nuclear atomic model.
Thomson's pudding model was of electrons in a cloud of positive charge. Rutherford's planetary model was of a dense nucleus with a positive charge and negatively charged electrons orbiting around the nucleus.