Question

question 30 (1 point)
the metals in groups 1a, 2a, and 3a
o a all form ions with a negative charge.
o b lose electrons when they form ions.
o c all have ions with a 1* charge.
o d gain electrons when they form ions

question 31 (1 point)
which of the following factors contributes to the decrease in ionization energy within a group in the periodic table as the atomic number increases?
o a increase in atomic size
o b fewer electrons in the highest occupied energy level
o c increase in number of protons
o d increase in size of the nucleus

question 32 (1 point)
which of the following elements has the smallest first ionization energy?
o a sodium
o b magnesium
o c potassium
o d calcium

Explanation:

Question 30

• Metals in Groups 1A, 2A, and 3A are electropositive. They tend to lose electrons to achieve a stable electron configuration. When they lose electrons, they form cations (positively - charged ions).
• Option a: Metals form positive ions (cations), not negative ions (anions). So, this option is incorrect.
• Option b: Metals lose electrons to form ions. For example, Group 1A metals lose 1 electron, Group 2A metals lose 2 electrons, and Group 3A metals lose 3 electrons. This option is correct.
• Option c: Group 1A metals form ions with a \(+1\) charge, Group 2A metals form ions with a \(+2\) charge, and Group 3A metals form ions with a \(+3\) charge. So, this option is incorrect.
• Option d: Metals lose electrons, not gain electrons, when forming ions. So, this option is incorrect.

• Ionization energy is the energy required to remove an electron from an atom.
• As the atomic number increases within a group:
• Option a: The atomic size increases. As the atomic size increases, the outermost electrons are farther from the nucleus. The electrostatic attraction between the nucleus and the outermost electrons decreases. So, less energy is required to remove an electron (ionization energy decreases). This option is correct.
• Option b: Within a group, the number of electrons in the highest - occupied energy level is the same. For example, all Group 1A elements have 1 electron in their highest - occupied energy level. So, this option is incorrect.
• Option c: An increase in the number of protons would, in theory, increase the attraction for electrons (if the electron - proton distance were constant). But within a group, the increase in atomic size (due to more electron shells) overcomes the effect of more protons. So, this option is incorrect.
• Option d: The increase in the size of the nucleus (due to more protons and neutrons) is not the main factor affecting ionization energy within a group. The increase in atomic size is the dominant factor. So, this option is incorrect.

• Ionization energy generally decreases down a group and increases across a period.
• Sodium (\(Na\)) and potassium (\(K\)) are in Group 1A, and magnesium (\(Mg\)) and calcium (\(Ca\)) are in Group 2A.
• Group 1A elements have lower ionization energies than Group 2A elements in the same period because Group 1A elements have one electron in their outermost shell, and it is easier to remove this single electron compared to Group 2A elements which have two electrons in their outermost shell.
• Between \(Na\) and \(K\), \(K\) is below \(Na\) in Group 1A. Since ionization energy decreases down a group, \(K\) has a lower ionization energy than \(Na\).

Answer:

b. lose electrons when they form ions

Question 31