Question 1

Which of the following statements best explains why the atomic radius decreases across a period from left to right in the periodic table?

Accepted Answer

Protons are added to the nucleus, increasing the effective nuclear charge and pulling electrons closer.

Question 2

Which element has the highest first ionization energy among the following: Na, Mg, Al, or Cl?

Accepted Answer

Cl

Question 3

What is the electron configuration of a neutral potassium atom (K, atomic number 19) using noble gas shorthand?

Accepted Answer

$$[Ar] 4s^1$

Question 4

Which of the following ions is largest in size: $$Na^+$$, $$Mg^{2+}$$, $$F^-$$, or $$O^{2-}$$? (All are isoelectronic)

Accepted Answer

$$O^{2-}$$

Question 5

Why does sodium (Na) commonly form a $$1^+$$ ion and not a $$2^+$$ ion?

Accepted Answer

Sodium has only one valence electron that is easily removed; removing a second electron would be more difficult because it would be a core electron.

Question 6

Which of the following elements is most likely to have the highest electron affinity?

Accepted Answer

Fluorine ($$F)$$

Question 7

A main-group element has an outer electron configuration of $$ns^2$$ $$np^4. $$What charge is likely for an ion of this element?

Accepted Answer

$$4-$$

Question 8

Which of the following best describes the trend in metallic character across a period from left to right?

Accepted Answer

Metallic character decreases.

Question 9

Which statement correctly explains why valence electrons are more important than core electrons in determining the reactivity and bonding in atoms?

Accepted Answer

Valence electrons are held most loosely and are involved in transfer or sharing during bonding.

Question 10

Which of the following elements is expected to have the largest atomic radius?

Accepted Answer

Potassium ($$K)$$

Question 11

Which of the following electron configurations represents a transition metal in its ground state?

Accepted Answer

$$[Ar] 4s^2$ 3d^6$

Question 12

Which of the following best describes the trend in first ionization energy as you move down a group in the periodic table?

Accepted Answer

First ionization energy decreases.

Question 13

Which of the following elements is most likely to form an anion with a $$2-$$ charge?

Accepted Answer

Oxygen ($$O)$$

Question 14

Which of the following is a property of metals?

Accepted Answer

Malleable and ductile

Question 15

Which of the following ions is smallest in size?

Accepted Answer

$$Ca^{2+}$$

Question 16

Which of the following elements has a completely filled $$p-$$sublevel in its outermost shell?

Accepted Answer

Neon ($$Ne)$$

Question 17

Which of the following best describes the electron affinity trend for halogens?

Accepted Answer

Halogens have the highest electron affinity in their period.

Question 18

Which of the following elements is most likely to be a good conductor of electricity?

Accepted Answer

Copper ($$Cu)$$

Question 19

Which of the following statements about transition metal electron configurations is correct?

Accepted Answer

Some transition metals have irregular electron configurations due to sublevel splitting.

Question 20

Which of the following best explains why $$F^- is $$smaller than $$O^{2-}$$, even though both are isoelectronic?

Accepted Answer

$$F^-$$ has a higher nuclear charge, pulling electrons closer.

Periodic Properties of the Elements – CHEM 1010 Study Notes

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