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periodic property
a property of an element that is predictable based on an element's position in the periodic table
electron configuration
a notation that shows the particular orbitals that are occupied by electrons in an atom
Ground state
The lowest energy state in an atom, ion, or molecule
Orbital diagram
A diagram that gives info similar to an electron configuration but symbolizes an electron as an arrow in a box representing an orbital, with he arrow's direction denoting the electron's spin
Pauli exclusion principle
The principle that no two electrons in an atom can have the same four numbers
Degenerate
A term describing two or more electron orbitals with the same value of n that have the same energy
Coulomb's law
A scientific law stating that the potential energy between two charged particles is proportional to the product of the charges divided by the distance that separates the charges
Shielding
The effect on an electron of repulsion by electrons in lower-energy orbitals that screen it from the full effects of nuclear charge
effective nuclear charge (Zeff)
the actual nuclear charge experienced by an electron, defined as the charge of the nucleus plus the charge of the shielding electrons
penetration
the phenomenon of some higher-level atomic orbitals having significant amounts of probability within the space occupied by orbitals of lower energy level
Aufbau principle
The principle that indicates the pattern of orbital filling in an electron
Hund's rule
the principle stating that when electrons fill degenerate orbitals, they first fill them singly with parallel spins
What did the experiments by Stern and Gerlach show?
a beam of silver atoms is split in two by a magnetic field and electrons spin on their axis
When electrons spin, what is generated?
Spinning charged particles generates a magnetic field.
If there are an even number of electrons, which direction of half the atoms does the net magnetic field point?
about half the atoms will have a net magnetic field pointing "north"
Which direction does the other half of atoms does the net magnetic field point?
other half will have a net magnetic field pointing "south."
What does all electrons have the same amount of?
Spin
What is the orinetation of the electron spin?
Quantized, can be in only one direction or its opposite.
What are the values of ms?
+1/2 or -1/2
How are orbital diagrams represented?
a square to represent each orbital and a half-arrow to represent each electron in the orbital.
What must be canceled in an orbital?
Spins
What does the direction of the arrow in an orbital diagram show?
the spin of the electron.
What is included in the pauli exclusion principle?
- No two electrons in an atom may have the same set of four quantum numbers.
- Therefore, no orbital may have more than two electrons, and they must have opposite spins.
What is composed in an s sublevel?
1 orbital; therefore, it can hold 2 electrons
What is composed in an p sublevel?
3 orbitals; therefore, it can hold 6 electrons.
What is composed in an d sublevel?
5 orbitals; therefore, it can hold 10 electrons.
What is composed in an f sublevel?
7 orbitals; therefore, it can hold 14 electrons.
What are the quantum numbers of Helium's electron?
- Helium has two electrons.
- Both electrons are in the first energy level.
- Both electrons are in the s orbital of the first energy level.
- Because they are in the same orbital, they must have opposite spins.
What do the sublevels in each principal energy shell of hydogen all have in common?
same energy or other single electron systems
What happens to the energies of multielectron atoms?
energies of the sublevels are split that are
caused by charge interaction, shielding, and penetration
What happens the value of the l quantum number is lowered?
less energy the sublevel has
s (l = 0) < p (l = 1) < d (l = 2) < f (l = 3)
What happens to like charges in coulomb's law?
potential energy (E) is positive and decreases as the particles get farther apart as r increases.
What happens to opposite charges in the coulomb's law?
potential energy is negative and becomes more negative as the particles get closer together.
What is affected by the strength of the interaction?
strength of the interaction increases as the size of the charges increases
What does each electron in a multielectron atom experience?
both the attraction to the nucleus and the repulsion by other electrons in the atom
Components of penentration?
- The closer an electron is to the nucleus, the more attraction it experiences
- The better an outer electron is at penetrating through the electron cloud of inner electrons, the more attraction it will have for the nucleus
- The degree of penetration is related to the orbital's radial distribution function.
What does the weaker penetration of the 2p sublevels mean?
electrons in the 2p sublevel experience more repulsive force; they are more shielded from the attractive force of the nucleus
What is indicated of the deeper penetration of the 2s electrons?
electrons in the 2s sublevel experience a greater attractive force to the nucleus and are not shielded as effectively
What occurs in the orbitals of the fourth and fifth principal levels?
the effects of penetration become so important that the s orbital lies lower in energy than the d orbitals of the previous principal level.
What happens to the energy separations between one set of orbitals?
energy separations between one set of orbitals and the next become smaller beyond the 4s.
What is shown from writing the electron configuartion?
listing of the sublevels in order of filling with the number of electrons in that sublevel written as a superscript.
What is short-hand way of writing an electron configuration?
use the symbol of the previous noble gas in brackets [] to represent all the inner electrons and then just write the last set.
valence electrons
Those electrons that are important in chemical bonding. For main-group elements, the valence electrons are those in the outermost principal energy level
core electrons
those electrons in a complete principal energy level and those in complete d and f sublevels
What is composed of the electron configuration in the periodic table?
- The main group number corresponds to the number of valence electrons.
- The length of each "block" is the maximum number of electrons the sublevel can hold.
- The period number corresponds to the principal energy level of the valence electrons.
How to Write an Electron Configuration Using the Periodic Table
- Locate the element on the periodic table.
- Locate the noble gas that precedes the element.
- Represent the inner electron configuration by writing the symbol of the noble gas in brackets.
- Determine the outer electron configuration by tracing the elements between the noble gas and the element of interest; assign electrons to the appropriate orbitals as you trace across the blocks on the periodic table
What are the properties of elements in electron configuration?
The properties of the elements follow a periodic pattern.
- Elements in the same column have similar chemical properties.
- The elements in a period show a pattern that repeats.
2. number of valence electrons and the types of orbitals they occupy are also periodic.
3. Elements with electron configurations closest to noble gases are most reactive.
What is the noble gas electron configuration?
The noble gases have eight valence electrons.
- Except for He, which has only two electrons
2. They are especially nonreactive.
- He and Ne are practically inert.
Why are noble gases nonreactive?
electron configuration of the noble gases is especially stable.
What is the electron configuration of alkail metals?
1. The alkali metals have one more electron than the previous noble gas.
2. In their reactions, the alkali metals tend to lose one electron, resulting in the same electron configuration as a noble gas.
- Form a cation with a 1+ charge
What is the electron configuration of halogens?
1. Have one fewer electron than the next noble gas
2. In their reactions with metals, halogens tend to gain an electron and attain the electron configuration of the next noble gas, forming an anion with charge 1−.
3. In their reactions with nonmetals, they tend to share electrons with the other nonmetal so that each attains the electron configuration of a noble gas
What is the electron configuration of metals and nonmetals?
These atoms form ions that will result in an electron configuration that is the same as the nearest noble gas.
van der Waals radius
one-half the distance between the centers of adjacent, nonbonding atoms in a crystal
Covalent radius
In nonmetals, one-half the distance between two atoms bonded together, and in metals one-half the distance between two adjacent atoms in a crystal of the metal
Atomic radius
The average bonding radius of an atom determined from measurements on a large number of elements and compounds
What happens to the atomic radius when moving across the period?
Atomic radius decreases
- Adding electrons to same valence shell
- Effective nuclear charge increases
- Valence shell held closer
What happens to the atomic radius when moving down group?
Atomic radius increases
- Valence shell farther from nucleus
-Effective nuclear charge fairly close
What does each letter represent in the effective nuclear charge?
Z is the nuclear charge, and S is the number of electrons in lower energy level
- Trend is s > p > d > f.
What happens when electrons are in a multielectron system?
electrons are simultaneously attracted to the nucleus and repelled by each other
What occurs to the outer electrons from the nucleus?
Outer electrons are shielded from the nucleus by the core electrons.
- Screening or shielding effect
- Outer electrons do not effectively screen for each other.
What occurs to the principal quantum number when moving down the column?
principal quantum number (n) of the electrons in the outermost principal energy level increases, resulting in larger orbitals and therefore larger atomic radii.
What occurs to the principal quantum number when moving to the right across a row in the periodic table?
the effective nuclear charge (Zeff) experienced by the electrons in the outermost principal energy level increases, resulting in a stronger attraction between the outermost electrons and the nucleus, and smaller atomic radii.
What happens to the atoms in the same group?
Atoms in the same group increase in size down the column.
What occurs to the atomic radii of transition metals?
Atomic radii of transition metals are roughly the same size across the d block.
- Much less difference than across main-group elements
- Valence shell ns^2, not the (n −1)d electrons
- Effective nuclear charge on the ns^2 electrons approximately the same
paramagnetic
the state of an atom or ion that contains unpaired electrons and is, therefore, attracted by an external magnetic field
diamagnetic
the state of an atom or ion that contains only paired electrons and is, therefore, slightly repelled by an external magnetic field
ionization energy
the energy required to remove an electron from an atom or ion in its gaseous state
What is formed when atoms lose electrons from the valence shell?
Cations
What is formed when nonmetals atoms gain enough electron to have eight valence electrons?
Anions
When transiton metals form cations, what happens to the electrons?
first electrons removed are the valence electrons, even though other electrons were added after.
Electrons may also be removed from the sublevel closest to the valence shell after the valence electrons
When does the ion size increases?
down the column
What is the effect of a large positive charge?
Small cation
Effect of a large negative charge?
Large anion
Explanation for the Trends in Anion Radius?
1. When atoms form anions, electrons are added to the valence shell.
2. These "new valence electrons" experience a smaller effective nuclear charge than the "old valence electrons," increasing the size.
3. The result is that the anion is larger than the atom.
What increases when tranversing down a group?
n level, causing the anions to get larger.
What decreases when transvering to the right across a period?
the effective nuclear charge for isoelectronic anions, causing the anions to get larger.
What is first ionization energy?
Energy to remove electron from neutral atom
What is second ionization energy?
energy to remove electron from 1+ ion, etc.
What are the general trends in the first ionization energy?
1. The larger the effective nuclear charge on the electron, the more energy it takes to remove it.
2. The farther the most probable distance the electron is from the nucleus, the less energy it takes to remove it.
When does the first ionization energy decreases?
Down the group
- Valence electron farther from nucleus
When does the first ionization energy increases?
across the period.
- Effective nuclear charge increases
What is the strength of attraction related to?
most probable distance the valence electrons are from the nucleus and the effective nuclear charge the valence electrons experience.
What happens to the orbital of an electron if it gets larger?
the farther its most probable distance will be from the nucleus and the less attraction it will have for the nucleus.
What does the quantum mechans predict?
the atom's first ionization energy should get lower down a column.
the atom's first ionization energy should get larger across a period.
What is increased when transvering across a period?
the effective nuclear charge on the valence electrons.
What are the exceptions in the first ionization energy?
1. First ionization energy generally increases from left to right across a period.
2. Except from 2A to 3A and 5A to 6A
3. To ionize N, you must break up a half-full sublevel, which costs extra energy.
4.When you ionize O, you get a half-full sublevel, which costs less energy.
What are the trends in successive ionization energies?
1. Removal of each successive electron costs more energy.
- Shrinkage in size due to having more protons than electrons
- Outer electrons closer to the nucleus; therefore harder to remove
2. There's a regular increase in energy for each successive valence electron.
3. There's a large increase in energy when core electrons are removed.
electron affinity
the energy change associated with the gaining of an electron by an atom in its gaseous state
How is having more energy released related to the electron affinity?
The more energy that is released, the larger the electron affinity, the more stable the anion.
Where does the alkali metals decreased electron afinity?
down the column.
- But not all groups do
- Generally irregular increase in E A from second period to third period
Where does the electron affinity increase?
"Generally" increases across period
- Becomes more negative from left to right
- Not absolute
- Group 5A generally lower E A than expected because extra electron must pair
-Groups 2A and 8A generally very low E A because added electron goes into higher energy level or sublevel
Which element has the highest electron affinity?
Halogen
What is metallic character?
how closely an element's properties match the ideal properties of a metal
- More malleable and ductile, better conductors, and easier to ionize
What happens to the metallic character when moving across a period?
Metallic character decreases left to right across a period.
- Metals found at the left of the period, and nonmetals to the right
What happens to the metallic character when moving down the column?
Metallic character increases down the column
- Nonmetals found at the top of the middle main-group elements, and metals found at the bottom
What kind of ionzation energies does metals and nonmetals have?
Metals generally have smaller first ionization energies, and nonmetals generally have larger electron affinities.
- Except for the noble gases
What does the quantum mechanic predict, regarding the atom's metallic character?
1. quantum mechanics predicts the atom's metallic character should increase down a column because the valence electrons are not held as strongly.
2. ∴ quantum mechanics predicts the atom's metallic character should decrease across a period because the valence electrons are held more strongly and the electron affinity increases.
What components does the trends in the alkali metals consist?
1. Atomic radius increases down the column.
2. Ionization energy decreases down the column.
3. Very low ionization energies
- Good reducing agents; easy to oxidize
- Very reactive; not found uncombined in nature
- React with nonmetals to form salts
- Compounds generally soluble in water ∴ found in seawater
What is decreased when moving down the column?
1. Electron affinity decreases down the column.
2. Melting point decreases down the column.
- All very low M P for metals
3. Density increases down the column.
- Except K
- In general, the increase in mass is greater than the increase in volume.
