All AP Chemistry Resources
Example Question #1 : Other Atomic Concepts
As atomic radius decreases, the force of attraction between the nucleus of the atom and its electrons __________.
cannot be determined
stays the same
As the atomic radius decreases, electrons are drawn closer to the nucleus. Since the electromagnetic force between the positively charged nucleus and negatively charged electrons is a function of distance, the force of attraction, or effective nuclear charge, exerted on each electron will be greater.
Example Question #2 : Other Atomic Concepts
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 , in this case , then write the rest of the electron configuration as normal.
Example Question #3 : Other Atomic Concepts
An electron falling to a lower energy level gives off a blue glow (λ=475nm). How much energy is emitted?
4.184 x 10-17 J
4.184 x 10-19 J
Energy is not emitted
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 #4 : Other Atomic Concepts
The atomic number of an atom is equal to the number of __________.
electrons + neutrons
protons + neutrons
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).