Question

trends in electronegativity

1. use table 6.2. what trend do you see in the relative electronegativity values of elements

within a group? within a period?

1. circle the letter of each statement that is true about electronegativity values.

a. the electronegativity values of the transition elements are all zero.
b. the element with the highest electronegativity value is sodium.
c. nonmetals have higher electronegativity values than metals.
d. electronegativity values can help predict the types of bonds atoms form.

1. use figure 6.24. circle the letter of each property for which aluminum has a higher

value than silicon.
a. first ionization energy c. electronegativity
b. atomic radius d. ionic radius

Explanation:

• Question 22:
• Within a group: As we move down a group in the periodic table, the number of electron shells increases. The outermost electrons are farther from the nucleus and are more shielded by the inner - shell electrons. So, the electronegativity decreases down a group.
• Within a period: As we move from left to right across a period, the atomic number increases. The number of protons in the nucleus increases, and the electrons are added to the same shell (no significant increase in shielding). So, the effective nuclear charge increases, and the electronegativity increases across a period.
• Question 23:
• a: Transition elements have non - zero electronegativity values. For example, iron (\(Fe\)) has an electronegativity value of about \(1.83\). So, this statement is false.
• b: Fluorine (\(F\)) has the highest electronegativity value (\(3.98\)), not sodium (\(Na\)) which has an electronegativity value of about \(0.93\). So, this statement is false.
• c: Non - metals tend to attract electrons more than metals. For example, oxygen (\(O\), electronegativity \(3.44\)) is a non - metal and sodium (\(Na\), electronegativity \(0.93\)) is a metal. So, non - metals have higher electronegativity values than metals. This statement is true.
• d: If the electronegativity difference between two atoms is small (\(<0.5\)), the bond is non - polar covalent. If it is between \(0.5\) and \(1.7\), the bond is polar covalent. If it is \(> 1.7\), the bond is ionic. So, electronegativity values can help predict the types of bonds atoms form. This statement is true.
• Question 24:
• a: First ionization energy generally increases across a period. Silicon (\(Si\)) has a higher first ionization energy than aluminum (\(Al\)) because \(Si\) has a more stable electron configuration (\(3s^{2}3p^{2}\) compared to \(Al:3s^{2}3p^{1}\)). So, this is false.
• b: Atomic radius decreases across a period. Aluminum (\(Al\)) has a larger atomic radius than silicon (\(Si\)) because as we move from \(Al\) to \(Si\) in period 3, the nuclear charge increases and pulls the electrons closer. So, this is true.
• c: Electronegativity increases across a period. Silicon (\(Si\)) has a higher electronegativity (\(1.90\)) than aluminum (\(Al\)) (\(1.61\)). So, this is false.
• d: For ions of the same charge, atomic radius trends are similar to ionic radius trends. \(Al^{3 +}\) and \(Si^{4+}\) are isoelectronic (\(10\) electrons). The ion with the higher nuclear charge (\(Si^{4+}\)) has a smaller ionic radius. So, \(Al\) (as \(Al^{3+}\)) has a larger ionic radius than \(Si\) (as \(Si^{4+}\)). This is true.

Answer:

• Question 22: Electronegativity decreases down a group and increases across a period.
• Question 23: C. Nonmetals have higher electronegativity values than metals; D. Electronegativity values can help predict the types of bonds atoms form.
• Question 24: B. atomic radius; D. ionic radius.