Units 16-17 Flashcards
What were the two questions that the Bohr model did not answer?
- Why were there special orbits?
- Why didn’t the electrons radiate when they were in these orbits?
Which model addresses the questions in the Bohr model?
Quantum model
What kind of waves do electrons moving around an atom set up?
Standing waves
True or False: 3D standing waves have nodes and antinodes
True
What does the amplitude of the standing wave of an electron to nucleus relationship represent?
The likelihood of finding an electron at that location.
When is the probability the highest to find an electron, a node or anti-node?
Anti-node
What is the probability of finding an electron in a node?
Zero
True or False: Since the standing wave pattern is stationary (within an atom) the probability of locating electrons at any given location doesn’t change with time
True
Why don’t electrons radiate in the quantum model?
Because they are confined to a static space, which means they are not accelerating around in an orbit. If they’re not accelerating, they’re not radiating.
How do electrons move?
In an orbital
Standing waves of probability
True or False: Electrons move in an orbit around a nucleus of an atom.
FALSE
What is an orbital?
A standing wave giving the probability of finding an electron in various locations around the nucleus of an atom.
Not an orbit, just an “orbital” space where an electron COULD be found inside an atom.
True or False: Electrons orbit the nucleus of an atom like planets orbit a star
False
True or False: There are different shapes of orbitals
True
What determines the shape of the orbital?
The number of standing waves and how those waves extend to space.
What are spherical harmonics?
The standard shapes of the orbitals
True or False: An electron in an atom has a fixed wavelength.
True
How does the quantum model explain why orbitals are discrete?
Because fixed wavelengths can only be set up (to create standing waves) at the exact right distance from the nucleus.
Imagine the string being shaken to create standing waves. They can only be created if they are WHOLE integers and the exact right distance apart to create nodes and anti-nodes.
What is spectroscopy?
The study of the brightness and wavelengths of the different frequencies of light emitted by excited atoms and ions.
True or False: The electron can be found inside the nucleus of an atom.
TRUE
But it’s extremely unlikely given the sizes.
How many types of orbitals are in the “p” orbital set?
3
Oriented on x, y, and z axis
What gives shape to atoms and molecules?
The directionality and orientation (cardinal points) of the lobes of an orbital
How many kinds of “d” orbitals are there?
5 total
4, four leaf clovers
1 dumbell with a donut
True or False: The Quantum model can also apply to the nucleus of an atom
True
What characteristics are the same within orbitals of the same type?
General form
What characteristics are DIFFERENT within orbitals of the same type?
Size, energy, radial shape
What is radial shape?
The cross section of an orbital that has been sliced through the center.
What is a shell?
A group of orbitals having similar energies and sizes.
True or False: Electrons in higher-numbered orbitals are more likely to be found farther from the nucleus.
True
True or False: Higher numbered orbitals also possess more energy than lower numbered orbitals of the same type
TRUE
Why do orbitals farther away have greater electrical potential energy?
Because the electrons are farther away from the protons. (opposite charges)
How many characteristics does an electron orbital have in an atom?
- Shape
- Shell
- Spin
What is spin in the context of electrons and orbitals?
The direction of the electron’s magnetic field.
It is NOT an electron spinning within an orbital.
True or False: Electrons have magnetic fields
True
How many directions can the spin of an electron be in?
2
Up and down
What is an eV?
Electron volt
A small amount of energy used to measure energies of particles in atoms.
What does the quantum model say about the movement of electrons within their orbitals?
That the places where they’re found doesn’t change with time. So the electrons are not moving or accelerating (and therefore, not radiating)
True or False: There’s a limit to how many waves can pass through a single point at one time.
False
True or False: Due to an electron’s wave nature, an infinite number of electrons can occupy the same orbital.
False
What is the exclusion principle?
The rule that two electrons cannot be in exactly the same state in an atom.
In other words, no two electrons in the same atom can have exactly the same shell, orbital, and spin values.
True or False: The exclusion principle says that even when two electrons have a probability of being in the same place at the same time, they cannot be in the same state.
True
What is an electron’s “state”?
Defined as its specific shell, orbital, and spin
True or False: An electron state is like an address with three pieces - shell, orbital, spin
True
Does a high energy or low energy orbital fill up first?
Low energy, closest to the nucleus.
True or False: In the quantum model, when an electron moves from a high energy orbital to a lower energy orbital, it releases the energy difference as a photon, just as with the Bohr model.
True
True or False: Orbitals are probability patterns.
True
How are the probability patterns of orbitals calculated?
By measuring the interactions between the negative electrons and positive nucleus.
What percentage of the time can we find electrons inside the orbitals?
90%
What is electronic structure?
The shorthand notation for what orbitals are occupied in a particular atom (looks like chem stuff)
How many electrons can be in a single orbital?
2
Which type of orbital is shaped like a sphere?
s orbital
True or False: An electron in a standing wave/orbital is moving like a particle.
FALSE
It’s moving like a wave
What happens to the number/kind of orbitals as the shell number increases?
Another kind of orbital will be added onto the ones in the shell below.
What is the study of chemistry?
The study of how atoms interact
What is the name for the electrical connections between atoms?
Bonds
Why do bonds form?
Because the positively charged nuclei attract not only their electrons, but also the electrons of OTHER atoms.
What is an element?
A substance that cannot be broken down further.
True or False: Elements contain only one TYPE of atom
True
What is the law of constant composition?
Substances contain a fixed, definite proportion of elements by mass.
What is atomic theory?
The model that matter is made up of atoms
What are the 5 postulates of atomic theory?
- Matter is composed of indivisible atoms
- An element contains only a single kind of atom, and all within that element are identical in every respect.
- Atoms of different elements have different mass and chemical reactivity.
- Chemical COMPOUNDS are composed of two or more atoms joined together in fixed ratios.
- Chemical REACTIONS are the rearrangement of atoms to form different compounds.
What are some flawed assumptions in Dalton’s atomic theory (which is otherwise correct)?
Atoms ARE divisible
Atoms of elements CAN differ slightly in mass without changing behavior.
4th assumption is true for most but not all substances.
Physical properties
Melting, boiling temperature, density, ionization potential, etc.
Chemical properties
Properties associated with the chemical reactivity of a material.
Who constructed the periodic table?
Mendeleev
What is the periodic law?
The properties of the elements are a periodic function of their atomic masses.
(all the numbers of the periodic table must be filled in, no gaps, there were predictable patterns)
What is the highest atomic number of naturally occurring atoms?
92
How do scientists create new elements?
Protons are accelerated to very high speeds and collided into heavier atoms. Sometimes those collisions form new atoms.
How long do MOST man-made elements live before decomposing?
millionths of a second
What is the atomic number?
How many protons are in a nucleus (equal to electrons)
What are the three major categories of the periodic table?
Metals
Nonmetals
Synthesized (man-made)
What are metals?
Good electrical and thermal conductors
Hammered into thin sheets or drawn into fine wires (malleable and ductile)
What are nonmetals?
Elements that do not conduct electricity
What percentage of the known elements are metals?
3/4
True or False: All but one of the metallic elements are solid at room temperature.
True
Mercury… weird
Which category on the periodic table shows the most variety in their properties?
Non-metals
Gases, liquids, solids at room temperature. Colored vs. colorless
What’s another name for families?
Groups
What are families or groups of elements?
Elements grouped because they have similar chemical properties, and the same number of valence electrons.
Are families listed vertically or horizontally on the periodic table?
VERTICALLY
What are the horizontal rows called on the periodic table?
Periods
What are periods?
Within a given row, physical and chemical properties change systematically from element to element.
What are the main group elements?
The set of metal and nonmetal elements designated with A column headings.
They have valence electron configurations involving only s and p electrons
Transition metals
B column headings.
Valence electron configurations involving d electrons.
What is a common feature of the actinide series?
They’re all radioactive.
Atomic size
Estimate of the volume occupied by an atom.
This number is obtained from the density of the solid state of the element.
Ionization energy
The amount of energy needed to completely remove an electron from an atom.
Varies with atomic number.
What does it mean for an atom to have a low ionization energy?
It is easy to strip an electron from an atom and ionize it.
It takes LOW energy to turn an atom into an ion. They lose electrons easily.
True or False: All metals have low ionization energies.
True
What is the reason metals are shiny and electrically conducting?
Because they have low ionization energies.
What family has the highest ionization energy?
Noble gases (helium, neon, argon, etc.)
True or False: Noble gases don’t tend to interact with other atoms because their ionization energies are so high.
True
What are valence electrons?
One or more electrons in the OUTERMOST populated shell of an atom.
What determine an element’s chemical reactivity?
Valence electrons
True or False: Atoms with completely filled shells are unreactive.
True
True or False: Repulsive forces between the electrons in an atom changes their energy levels.
TRUE
Atomic weight
the average atomic mass of all naturally-occurring forms of a particular atom.
What is a subshell?
S and p orbitals in a shell.
What determines what type of atom it is?
The number of protons
True or False: Ionized atoms have unequal numbers of protons and electrons.
True
True or False: When a shell or subshell is full, the atom is more stable
True
True or False: Valence electrons are part of the unfilled shells.
True
Why do families of elements have similar physical and chemical properties?
Because valence electrons determine reactivity/reactions, and they have the same number of valence electrons.
