Question

According to the general trend, the ionization energy for a period of elements (increases/decreases) proceeding from left to right in the periodic table.

Short answer

The ionization energy increases from left to right across a period.

Step-by-step solution

Understanding Ionization Energy

Ionization energy is the energy required to remove an electron from an atom in the gas phase. It generally reflects how strongly an atom holds onto its electrons.

Analyzing Periodic Trends

As we move across a period from left to right in the periodic table, the number of protons in the nucleus increases. This increases the positive charge in the nucleus, which in turn attracts electrons more strongly.

Effect of Nuclear Charge

With more protons, the effective nuclear charge experienced by the electrons increases. This means electrons are pulled closer to the nucleus, making it harder to remove an electron.

Conclusion on Ionization Energy

Due to the increased effective nuclear charge as we move from left to right, the ionization energy increases. This is because more energy is required to overcome the greater attraction between the nucleus and the electron.

Key concepts

Periodic Trends

When we talk about periodic trends in chemistry, we're discussing patterns that can be observed in the periodic table among elements. One of the key trends is how ionization energy changes as we move across a period (which is a row in the table). As you go from left to right across a period, the ionization energy increases. This means it becomes harder to remove an electron from the atoms. This happens due to two reasons: firstly, there are more protons in the nucleus as you move across a period, and secondly, there's a stronger attraction between these protons and the electrons. Understanding these periodic trends helps us make predictions about the behavior of elements and explains why elements in the same group or period have similar properties. Knowing this, you can predict that elements on the right side of the periodic table, like noble gases, generally have high ionization energies because their outer electrons are held very tightly by the nucleus.

Nuclear Charge

Nuclear charge refers to the total charge of the nucleus of an atom. This is directly related to the number of protons present in the nucleus. Each proton carries a positive charge, so more protons mean a stronger positive charge in the nucleus. One important concept to understand is "effective nuclear charge," which is the net positive charge experienced by electrons in an atom.

As you move across a period in the periodic table, the nuclear charge increases because more protons are being added to the nucleus. While you might think that adding more electrons would effectively shield this added charge, the electrons being added are in the same shell and do not fully shield the increased positive charge due to their similar energy levels.

Consequently, electrons feel a stronger pull towards the nucleus due to this increased effective nuclear charge. This explains why ionization energy, the energy needed to remove an electron, tends to increase across a period as each additional electron feels that strong pull from the nucleus.

Electron Removal

Removing an electron from an atom is known as ionization, and the energy needed for this process is called ionization energy. At a basic level, if you want to remove an electron, you need to overcome the attraction between the negatively charged electron and the positively charged nucleus. Here, the concept of nuclear charge really comes into play.

As previously mentioned, a higher nuclear charge results in a stronger attraction between the nucleus and electrons. Therefore, as the effective nuclear charge of an atom increases, it requires more energy to remove an electron from that atom. This relationship is part of why ionization energy increases across a period on the periodic table.

In simpler terms, the more protons (and hence higher positive charge) in the nucleus, the more tightly the electrons are held, making electron removal more difficult and demanding higher ionization energy. Understanding this concept is crucial in explaining the reactivity and bonding behavior of different elements.