Question

1. why does electronegativity increase when you move from left to right across a row of the periodic table?

the force the nucleus exerts on electrons decreases.
the distance from the nucleus to the bond increases.
the number of protons in the nucleus increases.
the number of electron shells decreases.

1. which neutral atom in row 3 of the periodic table is the least likely to lose an electron?

sodium (na)
aluminum (al)
phosphorus (p)
argon (ar)

Explanation:

Question 5

To determine why electronegativity increases left - to - right across a period, we analyze each option:

• Option 1: If the nuclear force on electrons decreased, electronegativity (which is the ability to attract electrons) would not increase. So this is incorrect.
• Option 2: As we move left - to - right across a period, the distance from the nucleus to the valence electrons (in the bond - forming region) does not increase. In fact, the effective nuclear charge increases, and the shielding from inner electrons remains relatively constant, so the distance doesn't have a trend of increasing. Thus, this is incorrect.
• Option 3: As we move from left to right across a row (period) of the periodic table, the atomic number increases. This means the number of protons in the nucleus increases. The increase in the number of protons leads to a greater positive charge in the nucleus. This greater positive charge exerts a stronger pull on the electrons (both the valence electrons and those in bonding situations), which increases the atom's electronegativity (the ability to attract electrons).
• Option 4: The number of electron shells remains the same when moving across a period. It is when moving down a group that the number of electron shells increases. So this is incorrect.

To find the atom in Row 3 least likely to lose an electron, we consider the concept of ionization energy (the energy required to remove an electron) and the stability of electron configurations:

• Sodium (Na): It has one valence electron. It is very likely to lose this electron to achieve a stable octet (like the noble gas configuration of Ne), so it has a low ionization energy and is likely to lose an electron.
• Aluminum (Al): It has three valence electrons. It can lose these electrons to achieve a stable electron configuration, so it is relatively likely to lose electrons compared to some other atoms in the row.
• Phosphorus (P): It has five valence electrons. While it can gain electrons to achieve an octet, it can also lose electrons (though less readily than Na or Al) in some chemical reactions.
• Argon (Ar): It is a noble gas with a full valence shell (8 electrons in its valence shell, following the octet rule). Atoms with full valence shells are extremely stable and have very high ionization energies. This means they are the least likely to lose an electron because losing an electron would disrupt their stable electron configuration.

Answer:

C. The number of protons in the nucleus increases.

Question 6