Expert Verified • Chemistry
Periodic Table Trends
How properties of elements change across the table.
The **Periodic Table Trends** refer to the patterns observed in the properties of elements as you move across a period (left to right) or down a group (top to bottom) in the periodic table. These trends include **atomic radius**, **ionization energy**, **electronegativity**, and **metallic character**. Understanding these trends is crucial because they help predict how elements behave in chemical reactions and their physical properties. For example, atomic radius decreases across a period due to increasing nuclear charge, while ionization energy generally increases. Down a group, atomic radius increases due to the addition of electron shells. These trends are rooted in the periodic table's organization by atomic number and electron configuration, making it a powerful tool for chemists and students alike.
Quick Recall Points
1
Atomic radius decreases across a period and increases down a group.2
Ionization energy generally increases across a period and decreases down a group.3
Electronegativity increases across a period and decreases down a group.4
Metallic character decreases across a period and increases down a group.5
Trends are directly related to electron configuration and nuclear charge.Active Recall Challenge
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What happens to atomic radius as you move from left to right across a period?
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Why does atomic radius decrease across a period?
Atomic radius decreases across a period because the nuclear charge increases, pulling electrons closer to the nucleus despite the addition of electrons in the same shell.
What causes ionization energy to increase across a period?
Ionization energy increases across a period due to the stronger attraction between the nucleus and electrons as the nuclear charge increases.
Why do elements become more metallic down a group?
Elements become more metallic down a group because the outer electrons are farther from the nucleus, making them easier to lose, a characteristic of metals.
What is the relationship between electronegativity and nonmetallic character?
Electronegativity and nonmetallic character both increase across a period because nonmetals gain electrons more readily, reflecting their higher electronegativity.