Question 1

Which scientist used periodic patterns in atomic properties to predict the existence and properties of undiscovered elements?

Accepted Answer

Dmitri Mendeleev

Question 2

What is the formula for effective nuclear charge ($$Z^*$$)?

Accepted Answer

$$Z^* = Z - S$$

Question 3

Which electrons provide the greatest shielding effect?

Accepted Answer

Electrons in lower shells

Question 4

As you move across a period in the periodic table, what happens to the effective nuclear charge ($$Z^*$$)?

Accepted Answer

$$Z^*$$ increases

Question 5

Why do atomic radii increase as you move down a group?

Accepted Answer

Number of electron shells increases

Question 6

Which of the following elements has the smallest atomic radius?

Accepted Answer

I

Question 7

What happens to the size of an atom when it loses an electron to form a cation?

Accepted Answer

The size decreases

Question 8

Rank the following ions in order of decreasing size: $$\mathrm{Na^+}$$, $$\mathrm{N$$^{3-}$$}$$, $$\mathrm{Mg$$^{2+}$$}$$, $$\mathrm{F^-}$$, $$\mathrm{O$$^{2-}$$}.$$

Accepted Answer

$$\mathrm{N$$^{3-}$$} \u003e O$$^{2-}$$ \u003e F^- \u003e Na^+ \u003e Mg$$^{2+}$$

Question 9

Which of the following elements has the smallest first ionization energy?

Accepted Answer

Pb

Question 10

Why is the third ionization energy of magnesium much higher than the first and second?

Accepted Answer

It disrupts a full shell

Question 11

What is electron affinity (EA)?

Accepted Answer

Energy released when a neutral atom accepts an electron

Question 12

Which group of elements generally has an electron affinity of zero?

Accepted Answer

Noble gases

Question 13

As you move across a period, how does electron affinity generally change?

Accepted Answer

It becomes more negative

Question 14

Which of the following best describes electronegativity ($$\chi$$)?

Accepted Answer

The ability of an atom in a bond to attract electrons to itself

Question 15

Which bond is more polar: O-H or O-F?

Accepted Answer

O-H, because the difference in electronegativity is greater

Question 16

Why do atomic radii stay about the same across the transition metals?

Accepted Answer

Both $$Z$$ and shielding increase, so $$Z^*$$ remains the same

Question 17

Which of the following statements about cations and anions is correct?

Accepted Answer

Cations are smaller and anions are larger than their parent atoms

Question 18

What is the main reason for the large jump in ionization energy after removing all valence electrons?

Accepted Answer

The next electron comes from a full shell, which is very stable

Question 19

Which element would you expect to have the highest electronegativity?

Accepted Answer

Fluorine

Question 20

Why does electron affinity become less negative as you move down a group?

Accepted Answer

There are more intervening shells, reducing the nucleus's hold on incoming electrons

Periodic Trends and Properties in the Elements

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