what is the trend for the size of the atom in the periodic table? across a row, down a column whhy does the ionization energy decrease down a column and increase across a row.
What is the trend for the size of the atom in the periodic table?
Answer:
In the periodic table, as you move from left to right across a row (period), the atomic size generally decreases. This trend is due to the increase in the effective nuclear charge, which attracts the electrons more strongly, pulling the electron cloud closer to the nucleus. On the other hand, as you move down a column (group), the atomic size tends to increase. This increase is because each subsequent element has an additional electron shell, leading to a greater distance between the nucleus and the outermost electrons, which results in a larger atomic size.
Why does the ionization energy decrease down a column and increase across a row?
Answer:
Ionization energy is the amount of energy required to remove an electron from an atom. The trend of decreasing ionization energy down a column and increasing it across a row in the periodic table is influenced by two main factors: atomic size and effective nuclear charge.
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Down a Column (Group):
- Ionization energy tends to decrease down a column because atoms become larger as you move down a group. With more electron shells, the outermost electrons are further from the nucleus, experiencing less attraction to the nucleus. This makes it easier to remove an electron, requiring less energy.
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Across a Row (Period):
- Ionization energy generally increases across a row due to the increase in effective nuclear charge. Even though the number of protons increases as you move across a period, the additional electrons are added to the same energy level, resulting in similar shielding effects. This means that the increased nuclear charge pulls the electrons more strongly, making it more difficult to remove an electron and requiring more energy.