AP Chemistry : Elements and Atoms
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Example Questions
Example Question #1 : Elements, Ions, And Isotopes
What is the shorthand electron configuration for gallium?
To write out the shorthand electronic configuration for Ga, you simply write down the noble gas that that comes before 
Example Question #2 : Other Atomic Concepts
An electron falling to a lower energy level gives off a blue glow (λ=475nm). How much energy is emitted?
3.14x10-37J
Energy is not emitted
3.14x10-40J
4.184 x 10-19 J
4.184 x 10-17 J
4.184 x 10-19 J
E=hf, or E=hc/λ
h is Planck's constant with a value of 6.62606957 × 10-34 m2 kg / s. Converting 475nm to m gives 4.75x10-7m. c is the speed of light with 3x108m/s. Putting these variables into the second equation you get 4.174x10-19J
Example Question #3 : Other Atomic Concepts
The atomic number of an atom is equal to the number of __________.
neutrons
protons
protons + neutrons
electrons
electrons + neutrons
protons
The atomic number is equal to the number of protons, because no two elements have the same number of protons. It is however possible for different elements to have the same number of electrons (through the loss or gain of electrons) or neutrons (isotopes).
Example Question #1 : Elemental Properties And Types
Sodium will react with oxygen and form an ionic compound. Which of the following is false concerning this interaction?
Both oxygen and the two sodiums are given stable octets by creating the ionic compound
In this compound, oxygen is the anion while the two sodium atoms are defined as cations
Sodium has a higher electronegativity than oxygen, causing it to give its electron to oxygen
The electrons are not equally shared between sodium and oxygen
The ionic compound has an overall neutral charge
Sodium has a higher electronegativity than oxygen, causing it to give its electron to oxygen
Electronegativity is defined as the tendency of an atom to attract an electron in a bond that it shares with another atom. Because oxygen wants to receive two elctrons, while both sodiums wish to lose one electron, oxygen has a higher electronegativity than sodium. Typically, electronegativity can be seen as increasing as you go to the top right of the periodic table. For example, fluorine has a higher electronegativity than nitrogen.
Example Question #2 : The Periodic Table
What is the energy required to form a gaseous cation from a gaseous atom?
Kinetic energy
Ionization energy
Free energy
Electronegativity
Ionization energy
This is the correct definition of ionization energy. By removing an electron from an atom, a cation is produced.
Example Question #3 : The Periodic Table
Why can some atoms exceed the octet rule?
They are very electronegative.
They have d-orbitals where the extra electrons can go
They are nonmetals
They do not exhibit any intermolecular forces
They have d-orbitals where the extra electrons can go
Atoms in the third period and above have d-orbitals that can hold up to 10 elecrons. This is what allows for atoms to exceed the octet rule.
Example Question #1 : The Periodic Table
What properties do metallic compounds have that others lack?
Brittle lattice structure
Solid at room temperature
Conductivity in the solid phase
Conductivity in the liquid phase
Conductivity in the solid phase
Metallic compounds have unique properties due to their electron motility. In metals, electrons are able to move freely around and between atoms. In non-metals, electrons are more tightly bound to the nucleus due to increased nuclear positive charge and decreased atomic radius. The fluidity of electrons in metals allows them to conduct electric charge.
Metals are generally non-brittle. Metals are solids at room temperature and conduct electricity in the liquid phase, but they share these properties with a number of non-metal compounds as well.
Example Question #3 : Elemental Properties And Types
Why are the transition metals good conductors of electricity?
Transition metals have only partially filled valence bands. Thus, the electrons can move among the d orbitals, and this electron flow allows the transition metals to be good conductors of electricity.
Example Question #2 : The Periodic Table
Which of the following does not determine the length of an element's atomic radius?
Number of valence electrons
Effective nuclear charge that electrons experience
Number of electron shells
Number of neutrons
Number of neutrons
The number of neutorns is the only thing out of the answer choices that does not impact an element's atomic radius. Since neutrons have no charge, they do not impact the attractive forces between electrons and protons.
Example Question #4 : The Periodic Table
Which of the following atoms is least likely to have a full octet when it is part of a molecule?
Cl
O
C
B
B
B (boron) is one of the atoms known for making fewer than 4 covalent bonds, and therefore not filling its octet. C (carbon) always makes 4 bonds, while O (oxygen) and Cl (chloride) are also known for having full octets.
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