1.8 Valence Electrons & Ionic Compounds

The first five ionization energies of a second-period element are listed in the table above. Which of the following correctly identifies the element and best explains the data in the table?

• B, because it has five core electrons
• B, because it has three valence electrons
• N, because it has five valence electrons
• N, because it has three electrons in the p sublevel

1s2 2s2 2p6 3s2 3p3 Atoms of an element, X, have the electronic configuration shown. The compound most likely formed with magnesium, Mg, is

• MgX
• Mg₂X
• MgX₂
• MgX₃
• Mg₃X₂

Forms monatomic ions with 2– charge in solu­tions

• F
• S
• Mg
• Ar
• Mn

If Na reacts with chlorine to form NaCl , which of the following elements reacts with Na to form an ionic compound in a one-to-one ratio, and why?

• K , because it is in the same group as Na .
• Mg , because its mass is similar to that of Na .
• Ar , because its mass is similar to that of Cl .
• Br , because it has the same number of valence electrons as Cl .

All the chlorides of the alkaline earth metals have similar empirical formulas, as shown in the table above. Which of the following best helps to explain this observation?

• Cl2(g) reacts with metal atoms to form strong, covalent double bonds.
• Cl has a much greater electronegativity than any of the alkaline earth metals.
• The two valence electrons of alkaline earth metal atoms are relatively easy to remove.
• The radii of atoms of alkaline earth metals increase moving down the group from Be to Ra .

Which of the following ions has the same number of electrons as Br - ?

• Ca2+
• K+
• Sr2+
• I-
• Cl-

Which of the following best helps to explain why  Na(s)  is more reactive with water than  Mg(s) is?

• Na(s) is softer than Mg(s) .
• The atomic mass of Na is less than that of Mg .
• The Na+ ion has weaker Coulombic attraction to an anion than the Mg2+ ion has.
• The first ionization energy of Na is less than that of Mg .

Which of the following elements is most likely to form a covalent bond with chlorine?

• Na

• Mg

• O

• K

Which of the following best explains why fluorine is more electronegative than iodine?

• Fluorine has a smaller atomic radius than iodine.

• Fluorine has more protons than iodine.

• Fluorine is in a higher period than iodine.

• Fluorine has a lower ionization energy than iodine.

Which of the following ions has the same number of electrons as Ne?

• O2-

• F-

• Na+

• Mg2+