Respuesta :
Answer:III. Electronegativity increases from left to right in a period.
Explanation: [tex]Z_{eff}[/tex] here means the effective nuclear charge on electrons due to protons present in the nucleus of an atom.
Electrons in outer energy shells feel a weaker pull from the nucleus than the inner electrons because the inner electrons "shield" (due to their negative force) some of the positive force coming from the protons in the nucleus.
From left to right on the periodic table, [tex]Z_{eff}[/tex] increases because the number of shielding electrons within each row stays constant while the number of protons increases. [tex]Z_{eff}[/tex] is one of the factors in the size of an atom. If an atom has a strong pull on its outer electrons, the atom as a whole will be smaller. Despite knowing [tex]Z_{eff}[/tex] , it is very difficult to determine the size of an atom, which is the size of the electron cloud around the nucleus of an atom. But because we can never know the exact location of an electron, we cannot actually specify the size of an atom.
Assuming that the atom is a perfect sphere. We can then determine an atomic radius by measuring the nucleus to the edge of the spherical cloud of electrons. There are a variety of experimental and theoretical methods to determine or calculate the atomic radius for an element. Using these radii, going from left to right across the periodic table, the atomic radius decreases because effective nuclear charge increases.
Ionization energy decreases from top to bottom in a group because the the no. of shells increases in and the size of the atom increases so, the electrons that are far away from the nucleus feeling less force of attraction of the proton from the nucleus and are higher in energy hence are lost much more easily by gaining a little more energy.
Electronegativity is a tendency to attract a shared pair of electron in a covalent bonding which develops partial polarity in the participating atoms.Going across a period,
- Effective Nuclear Charge ([tex]Z_{eff}[/tex]) increases.
- Distance and shielding remain constant.
