Other Atomic Concepts

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1

As atomic radius decreases, the force of attraction between the nucleus of the atom and its electrons __________.

increases

CORRECT

decreases

0

stays the same

0

cannot be determined

0

Explanation

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.

2

An electron falling to a lower energy level gives off a blue glow (λ=475nm). How much energy is emitted?

3.14x10-40J

0

4.184 x 10-19 J

CORRECT

4.184 x 10-17 J

0

3.14x10-37J

0

Energy is not emitted

0

Explanation

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

3

The atomic number of an atom is equal to the number of __________.

protons

CORRECT

electrons

0

neutrons

0

protons + neutrons

0

electrons + neutrons

0

Explanation

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).

4

What is the shorthand electron configuration for gallium?

CORRECT

0

0

0

0

Explanation

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.